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NOVEL DAIRY PROCESSING TECHNOLOGIES Techniques, Management, and Energy Conservation Innovations in Agricultural and Biological Engineering NOVEL DAIRY PROCESSING TECHNOLOGIES Techniques, Management, and Energy Conservation Edited by Megh R. Goyal, PhD Anit Kumar, MTech Anil K. Gupta, PhD Apple Academic Press Inc. 3333 Mistwell Crescent Oakville, ON L6L 0A2 Canada Apple Academic Press Inc. 9 Spinnaker Way Waretown, NJ 08758 USA © 2018 by Apple Academic Press, Inc. Exclusive worldwide distribution by CRC Press, a member of Taylor & Francis Group No claim to original U.S. Government works Printed in the United States of America on acid-free paper International Standard Book Number-13: 978-1-77188-612-3 (Hardcover) International Standard Book Number-13: 978-1-315-16712-1 (eBook) All rights reserved. No part of this work may be reprinted or reproduced or utilized in any form or by any electric, mechanical or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publisher or its distributor, except in the case of brief excerpts or quotations for use in reviews or critical articles. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission and sources are indicated. Copyright for individual articles remains with the authors as indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the authors, editors, and the publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors, editors, and the publisher have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged, please write and let us know so we may rectif; y in any future reprint. Trademark Notice: Registered trademark of products or corporate names are used only for explanation and identification without intent to infringe. Library and Archives Canada Cataloguing in Publication Novel dairy processing technologies : techniques, management, and energy conservation / edited by Megh R. Goyal, PhD, Anit Kumar, MTech, Anil K. Gupta, PhD. (Innovations in agricultural and biological engineering) Includes bibliographical references and index. Issued in print and electronic formats. ISBN 978-1-77188-612-3 (hardcover).--ISBN 978-1-315-16712-1 (PDF) 1. Dairy products industry--Technological innovations. 2. Dairy processing. 3. Milk--Pasteurization. I. Goyal, Megh Raj, editor II. Kumar, Anit, editor III. Gupta, Anil K., 1966- editor IV. Series: Innovations in agricultural and biological engineering SF250.5.N68 2017 637 C2017-907441-5 C2017-907442-3 Library of Congress Cataloging-in-Publication Data Names: Goyal, Megh Raj, editor. | Kumar, Anit, editor. | Gupta, Anil K. (Anil Kumar), 1966- editor. Title: Novel dairy processing technologies : techniques, management, and energy conservation / editors: Megh R. Goyal, Anit Kumar, Anil K. Gupta. Description: Waretown, NJ : Apple Academic Press, 2017. | Series: Innovations in agricultural & biological engineering ; volume 17 | Includes bibliographical references and index. Identifiers: LCCN 2017055545 (print) | LCCN 2017056542 (ebook) | ISBN 9781315167121 (ebook) | ISBN 9781771886123 (hardcover : alk. paper) Subjects: LCSH: Dairy processing. | Dairying. Classification: LCC SF250.5 (ebook) | LCC SF250.5 .N684 2017 (print) | DDC 338.4/7637--dc23 LC record available at https://lccn.loc.gov/2017055545 Apple Academic Press also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic format. For information about Apple Academic Press products, visit our website at www.appleacademicpress.com and the CRC Press website at www.crcpress.com CONTENTS List of Contributors.................................................................................. vii List of Abbreviations................................................................................. xi Preface 1 by: Megh R. Goyal....................................................................xv Preface 2 by: Anit Kumar.......................................................................xvii Foreword 1 by: D. C. Saxena...................................................................xix Foreword 2 by: Ashutosh Upadhyay........................................................xxi Foreword 3 by: Vijender Mishra........................................................... xxiii Warning/Disclaimer................................................................................ xxv About the Senior Editor-in-Chief..........................................................xxvii About Co-Editor Anit Kumar.................................................................xxix About Co-Editor Anil K. Gupta.............................................................xxxi Other Books on Agricultural & Biological Engineering.....................xxxiii Editorial.............................................................................................. xxxvii PART I: Emerging Processing Technologies in the Dairy Industry.... 1 1. Technology of Ohmic Heating for the Pasteurization of Milk................. 3 Asaad Rehman Saeed Al-Hilphy, Haider I. Ali, and Ghassan F. Mohsin 2. Advances in Microwave-Assisted Processing of Milk............................. 47 S. S. Shirkole and P. P. Sutar 3. Advancement in the Ghee Making Process............................................. 61 Pramod Kumar, Raman Seth, Hitesh Patel, Anit Kumar, Durga Shankar Bunkar, and Mohammed Nayeem 4. Technological Interventions in Kulfi Production: A Review..................... 75 Kumaresh Halder, Amit Juneja, Subrota Hati, and Chandan Solanki 5. Hybrid Technology for the Pasteurization of Milk................................. 93 Shilpi Singh, Jayeeta Mitra, and Viswanatha Angadi vi Contents PART II: Drying Techniques in the Dairy Industry..........................115 6. Classification of Dried Milk Products.................................................... 117 Rachna Sehrawat, Prabhat Kumar Nema, Pramod Kumar, and Anit Kumar 7. Osmotic Dehydration: Principles and Applications in the Dairy Industry.......................................................................................... 135 Adarsh M. Kalla and Devaraju Rajanna PART III: Energy Conservation: Opportunities in the Dairy Industry............................................................................... 155 8. Food Safety and Management Systems (FSMS): Applications in the Dairy Industry............................................................................... 157 Angadi Viswanatha, C. Ram Kumar, Jayeeta Mitra, and S. S. Roopa 9. Economic Analysis of Milk Marketing: Case Study in Haryana......... 177 Anil K. Gupta 10. Dairy Foods: Allergy and Intolerance.................................................... 225 Mohammed Nayeem, Gurdeep Rattu, Rohant Dhaka, Ajay Kumar Kashyap, Nishant Kumar, and Pramod Kumar PART IV: Management Systems and Hurdles in the Dairy Industry.................................................................................241 11. Day Lighting in Dairy Farms.................................................................. 243 Bhavesh B. Chavhan, A. K. Agrawal, C. Sahu, S. S. Chopde, and Adarsh M. Kalla 12. Refrigeration Principles and Applications in the Dairy Industry ...... 253 A. G. Bhadania 13. Energy Audits and Its Potential as a Tool for Energy Conservation in the Dairy Industry .............................................................................. 269 A. G. Bhadania Glossary of Technical Terms........................................................................... 283 Index.................................................................................................................. 291 LIST OF CONTRIBUTORS Adarsh M. Kalla Department of Dairy Engineering, Dairy Science College, Karnataka Veterinary Animal and Fisheries Sciences University, Mahagoan Cross, Kalaburagi 585316, Karnataka India. E-mail: firstname.lastname@example.com Ajay Kumar Kashyap Department of Agricultural and Environmental Science, National Institute of Food Technology Entrepreneurship and Management (NIFTEM) Kundli, Haryana, India Amit Juneja National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat 131028 Haryana, India Angadi Viswanatha Department of Food Microbiology, Agriculture College Hassan, University of Agricultural Sciences (UAS), Bangalore 573225, India. E-mail: email@example.com Anil K. Gupta Department of Agricultural Economics, College of Agriculture, CCS Haryana Agricultural University, Hisar 125004, Haryana, India. E-mail: email@example.com firstname.lastname@example.com Anit Kumar Department of Food Science and Technology, National Institute of Food Technology Entrepreneurship and Management, Plot No. 97, Sector 56, HSIIDC Industrial Estate, Kundli, Sonipat 131028, Haryana, India. E-mail: email@example.com Asaad Rehman Saeed Al-Hilphy Department of Food Science, College of Agriculture, University of Basrah, Basrah City, Iraq. E-mail: firstname.lastname@example.com Ashok K. Agrawal Department of Dairy Engineering, College of Dairy Science and Food Technology, Chhattisgarh Kamdhenu Vishwavidyalaya (CGKV), Raipur 492012 India, E-mail: firstname.lastname@example.com Ashutosh Upadhyay National Institute of Food Tech. Entrepreneurship & Management (NIFTEM), Plot No. 97, Sector 56, HSIIDC Industrial Estate Kundli, Sonipat 131028, Haryana India. E-mail: email@example.com Bhavesh B. Chavhan Department of Dairy Engineering, College of Dairy Technology Maharashtra Animal and Fisheries Sciences University, Udgir, Nagpur 413517, India. E-mail: firstname.lastname@example.com; email@example.com C. Ram Kumar Department of Food Science and Technology, College of Agriculture, Hassan, University of Agricultural Sciences, Bangalore 573225, India viii List of Contributors C. Sahu Department of Dairy Engineering, College of Dairy Science and Food Technology, Chhattisgarh Kamdhenu Vishwa Vidyalaya (CGKV), Raipur 492012, India Chandan Solanki ICAR-Central Institute of Post-Harvest Engineering and Technology, Ludhiana 141001, Punjab, India. E-mail: firstname.lastname@example.com D. C. Saxena Sant Longowal Institute of Engineering & Technology, Longowal, 148106, Sangrur Punjab, India. E-mail: firstname.lastname@example.com Devaraju Rajanna Department of Dairy Engineering, Karnataka Veterinary Animal and Fisheries Sciences University, Dairy Science College, Mahagoan Cross, Kalaburagi 585316, Karnataka, India Durga Shankar Bunkar Centre of Food Science and Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India G. Bhadania Department of Dairy Engineering, Sheth M. C. College of Dairy Science, Anand Agricultural University, Anand 388110, India. E-mail: firstname.lastname@example.com Ghassan F. Mohsin Vocational School, Maysan City, Iraq. E-mail: email@example.com Gurdeep Rattu Department of Basic and Applied Science, National Institute of Food Technology Entrepreneurship and Management (NIFTEM) Kundli, Haryana, India Haider I. Ali Department of Food Science, College of Agriculture, University of Basrah, Basra City, Iraq. Hitesh Patel Dairy Chemistry Division, National Dairy Research Institute, Karnal 132001, Haryana, India Jayeeta Mitra Department of Agricultural and Food Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India. E-mail: firstname.lastname@example.com; firstname.lastname@example.com Kumaresh Halder National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat 131028 Haryana, India. E-mail: email@example.com Megh R. Goyal Retired Faculty in Agricultural and Biomedical Engineering from General Engineering Department, University of Puerto Rico – Mayaguez Campus; and Senior Technical Editor-in-Chief in Agriculture Sciences and Biological Engineering, Apple Academic Press Inc., USA. E-mail: firstname.lastname@example.com Mohammed Nayeem Department of Food Science and Technology, National Institute of Food Technology Entrepreneurship and Management (NIFTEM) Kundli, Haryana, India. E-mail: firstname.lastname@example.com List of Contributors ix Nishant Kumar Department of Agricultural and Environmental Science, National Institute of Food Technology Entrepreneurship and Management (NIFTEM), Kundli, Haryana, India P. P. Sutar Department of Food Process Engineering, National Institute of Technology, Rourkela 769008, Odisha, India. E-mail: email@example.com; email@example.com Prabhat Kumar Nema Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Plot No. 97, Sector 56, HSIIDC Industrial Estate, Kundli, Sonipat 131028, Haryana Pramod Kumar Dairy Chemistry Division, National Dairy Research Institute (NDRI), Karnal 132001, Haryana, India. E-mail: firstname.lastname@example.com Rachna Sehrawat Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Plot No. 97, Sector 56, HSIIDC Industrial Estate, Kundli, Sonipat 131028, Haryana, India. E-mail: email@example.com Raman Seth Dairy Chemistry Division, National Dairy Research Institute, Karnal 132001, Haryana, India Rohant Dhaka Department of Food Science and Technology, National Institute of Food Technology Entrepreneurship and Management (NIFTEM) Kundli, Haryana, India S. S. Roopa Britannia Industries Ltd., Plot # 23, Bidadi Industrial Area, Bidadi Hobli, Ramanagara 562109 Karnataka, India S. S. Shirkole Department of Food Process Engineering, National Institute of Technology, Rourkela 769008, Odisha, India Santosh S. Chopde Department of Dairy Engineering, College of Dairy Technology at Udgir, COVAS Campus, Kavalkhed Road, Udgir 413517 (MS), India Shilpi Singh Food Process Engineering, Department of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur 721302, India. E-mail: firstname.lastname@example.com Subrota Hati SMC College of Dairy Science, Anand Agricultural University (AAU), Anand 388001, Gujarat, India Vijendra Mishra Department of Basic and Applied Sciences, National Institute of Food Tech. Entrepreneurship & Management (NIFTEM), Plot No. 97, Sector 56, HSIIDC Industrial Estate, Kundli, Sonipat 131028, Haryana, India LIST OF ABBREVIATIONS Ab ALP ASHARE ATP AU BEE BSA bST CCL CCP CFU CGKV CGR CIP CMA CO2 COD COP CRI CRIE CV D D1 D2 D3 DM EpiPen antibody associated alkaline phosphatase American Society of Heating, Air Conditioning and Refrigerating Engineers adenosine tri phosphate American unit Bureau of Energy Efficiency bovine serum albumin bovine somatotropin critical control limit critical control point colony forming units Chhattisgarh Kamdhenu Vishwavidyalaya compound growth rate clean-in-place cow's milk allergy carbon dioxide chemically oxygen demand coefficient of performance color rendition index crossed radio-immuno electrophoresis coefficient of variation diffusion coefficient of water from homogeneous material during osmotic dehydration diffusion coefficients of water from the core of the material to the dehydration front diffusion coefficients of water from the core of the material to across the front diffusion coefficients of water from the core of the material through the osmotically treated material into the osmotic solution dry matter epinephrine xii ESL ETP Fc FFA FSMS FSSAI GC GC–MS GHG GMP HACCP HDDCF HP HPH HPP HPS HTST HX ICAR IDF Ig IgE IGF INR ISO IU KDa kV L/d LAB LDL Lf LP LTLT M/MO MH MSNF MSU List of Abbreviations extended shelf life effluent treatment plant foot candles free fatty acids food safety management system Food Safety and Standards Authority of India gas chromatography gas chromatography and mass spectroscopy greenhouse gas good manufacturing practices hazard analysis and critical control point Haryana Dairy Development Cooperative Federation Ltd. high pressure high pressure homogenization high pressure processing high pressure sodium high temperature short time heat exchanger Indian Council of Agricultural Research International Dairy Federation immunoglobin immunoglobulin E insulin-like growth factor Indian rupees International Organization for Standards international unit kilodalton kilovolt liters per day lactic acid bacteria long-day lighting lactoferrin low pressure low temperature long time relative moisture content metal halide milk solids not fat Michigan State University List of Abbreviations NACICMR NCA NDRI NGOs NIFTEM NIR NLT NMT OFP OPRP PEF PFA PRL PRP RHT RLU SG SNF SPC SSOPs TBA TES TNDC TR UASB UASI UHT USFDA VCRS ZP α-Lac β-Lg Δx xiii Nutritional Advisory Committee of the Indian Council of Medical Research National Commission on Agriculture National Dairy Research Institute non-government agencies National Institute of Food Technology Entrepreneurship and Management near infrared not less than not more than operation flood program operational pre-requisite program pulse electric field prevention of food adulteration hormone prolactin pre-requisite program reduced heat treatment relative light units specific gravity solids not fat system performance coefficient sanitary standard operating procedures thiobarbituric acid thermal energy storage system Tamil Nadu Dairy Development Corporation ton of refrigeration up-flow anaerobic sludge blanket reactor ultrasonication-assisted spray ionization ultra-high temperature United States Food and Drug Administration vapor compressor refrigeration system cell disintegration index alpha-lactalbumin beta-lactoglobulin thickness of moving dehydration front PREFACE 1 Milk is nutritious, appetizing, and nature's perfect food; it is recommended by nutritionists for the development of a sound body and is consumed by all sectors of people. Demand for milk is greater in developed countries as compared to developing countries, but the gap has narrowed due to an increase in urbanization, population, and consumption. India ranks first in milk production, accounting for 18.5% of world production, achieving an annual output of 146.3 million tons during 2014–2015 as compared to 137.69 million tons during 2013–2014, recording a growth of 6.26%, whereas the Food and Agriculture Organization (FAO) has reported a 3.1% increase in world milk production from 765 million tons in 2013 to 789 million tons in 2014. Pasteurized milk and ultra-high temperature (UHT) milk market share in 2014 has increased to 83.7 and 6.9% (by volume), respectively, compared to 81.9 and 5.2% in 2013. A milk product is produced from the milk of mammals. Dairy products are usually high energy-yielding food products. A production plant for the processing of milk is called a dairy or a dairy factory. Apart from breastfed infants, the human consumption of dairy products is sourced primarily from the milk of cows, water buffaloes, goats, sheep, yaks, horses, camels, domestic buffaloes, and other mammals. Dairy products are commonly found throughout the world. I recall my childhood. I was breastfed by mother until I was 8 years old. It calmed me down from my nervousness and hypertension and imparted to me security in the lap of my mother. Until I was in fifth grade, I and my paternal family never tasted dairy milk except a few drops in an Indian tea. In sixth grade, once a day, I and my classmates were asked to sit on a 1 × 50 m2 mat and were served one 16-oz glass of milk (that was prepared from milk powder of American origin) by American Peace Corps volunteers. I enjoyed not only drinking the milk but also the dedication of these volunteers. What a gesture to the undernourished students in developing countries! At the 49th annual meeting of the Indian Society of Agricultural Engineers at the Punjab Agricultural University (PAU) during February 22–25 of 2015, a group of ABEs and FEs convinced me that there is a dire need to xvi Preface 1 publish book volumes on focus areas of agricultural and biological engineering (ABE). This is how the idea was born on the new book series titled Innovations in Agricultural & Biological Engineering. This book volume 17, Novel Dairy Processing Technologies: Techniques, Management and Energy Conservation, under this book series contributes to the ocean of knowledge on dairy engineering. The contributions by the cooperating authors to this book volume have been most valuable in the compilation. Their names are mentioned in each chapter and in the list of contributors. This book would not have been written without the valuable cooperation of these investigators, many of whom are renowned scientists who have worked in the field of dairy engineering throughout their professional careers. I am glad to introduce Anit Kumar, who is at present a PhD research scholar in the Department of Food Science and Technology at the National Institute of Food Technology Entrepreneurship and Management, Kundli, Haryana, India. His propensity for learning, inquiry and discovery of new facts has inspired him to opt for independent research as a career in dairy science. Dr. Anil K. Gutpa contributed his editorial skills to this book volume. Without their support and leadership qualities as co-editors of this book volume and the extraordinary work on dairy engineering applications, readers will not have this quality publication. I would like to thank the editorial staff, Sandy Jones Sickels, Vice President, and Ashish Kumar, Publisher and President, at Apple Academic Press, Inc., for making every effort to publish the book when food and water issues are major issues worldwide. Special thanks are also due to the AAP Production Staff. I request that readers to offer constructive suggestions that may help to improve the next edition. I express my deep admiration to my family for their understanding and collaboration during the preparation of this book volume. As an educator, there is a piece of advice to one and all in the world: "Permit that our almighty God, our Creator, provider of all and excellent Teacher, feed our life with Healthy Milk and Milk Products and His Grace—and Get married to your profession" —Megh R. Goyal, PhD, PE Senior Editor-in-Chief PREFACE 2 Dairy science has been an attractive discipline for more than 100 years. Milk and milk products are important diets of people throughout the world. The importance of milk as a source of multi-nutritional components is a well-established fact. It is also being used as a raw material by several dairy processing industries. At present, several books are available on the market written on dairy processes, dairy products, hurdles and management in dairy industries but they all seem to be scattered. This book is intended to cover the most important topics, such as processing, products, hurdles, management and energy conservation. The book consists of four parts. Part I is devoted to the application of novel processing technologies in the dairy industry, where four chapters have been included: Technology of ohmic heating for pasteurization of milk, Advances in microwave-assisted processing of milk, Hybrid technology for pasteurization of milk, and Advancement in the ghee making process. Part II is "Novel Drying Techniques in the Dairy Industry," with two chapters on classification of dried milk products, and osmotic dehydration: principles and applications in the dairy industry. Part III focuses on management systems and hurdles in the dairy industry and includes three chapters on Food safety and management system (FSMS): applications in the dairy industry, Economic analysis of milk marketing: case study in Haryana, and dairy foods: allergy and intolerance. Part IV covers "Energy Conservation: Opportunities in the Dairy Industry," with three chapters that focus on Day lighting in dairy farms, Refrigeration principles and applications in the dairy industry, and Energy audits and its potential as a tool for energy conservation in the dairy industry. We hope that the book will provide clear concepts about novel processing in the dairy sector. It also aims to answer questions related to hurdles, management, and energy conservation in the dairy sector. The book has been particularly written for food science students, researchers, academics, and professionals in the food industry. I am highly thankful to all the authors of individual chapters for their sincere efforts in writing the assigned book chapter. I also owe my gratitude to Professor Megh R. Goyal for his support and arduous job to bring the xviii Preface 2 book into its final form. I also acknowledge the help from Apple Academic Press Inc. for providing the opportunity to publish this book. I sincerely acknowledge the support received from Dr. Ajit Kumar (Vice Chancellor, NIFTEM, India); my research guide Dr. Ashutosh Upadhyay (Associate Professor, FST Department, NIFTEM, India); and Co-research guide Dr. Vijendra Mishra (Associate Professor, BAS Department, NIFTEM, India); Dr. Rupesh S. Chavan (Senior Executive, Mother Dairy Fruit and Vegetable Pvt. Ltd., Department of Quality Assurance, Gujarat, India); Dr. P.K. Nema (Associate Professor, FE Department, NIFTEM, India); and Dr. D.C. Saxena (Professor, Food Engineering Department, SLIET, India). I thank my grandparents, my parents Pramila Singh and Ashok K. Singh, elder brother Amit K. Singh and his wife Poonam Srivastava, my younger brother Anish K. Singh, and my colleagues Rachna Sehrawat, Onkar A. Babar, and Sandeep K. Gaikwad at the National Institute of Food Technology Entrepreneurship and Management, Haryana, India, for their constant love and affection. —Anit Kumar Co-Editor FOREWORD 1 BY D. C. SAXENA This book provides an insight into innovations and the latest research and policies being adopted in the dairy sector. This sector has immense growing opportunities and challenges for farmers, entrepreneurs, and industrialists as well as for academicians and researchers. The editors have put great effort to present the scientific research on drying of dairy products, management practices, advanced processing technology and hurdles in the sector. The most important highlight is the "Energy Conservation: Opportunities in the Dairy Industry." It is the need of the hour to focus on technologies and innovations to reduce the requirements of energy and its utilization in the best possible way. I wish for the success of the book and hope it will be a good source of literature for people who are involved in dairy industry growth and making it stronger day by day and help them to overcome the challenges. D. C. Saxena, PhD Professor (Food Process Engineering), Former Head of the Department Food Engineering & Technology, Former Dean (Planning & Development) Sant Longowal Institute of Engineering & Technology Longowal, 148106. District Sangrur (Punjab), India E-mail: email@example.com FOREWORD 2 BY ASHUTOSH UPADHYAY Milk is valued as one of the most complicated food systems, and therefore, extensive studies have been performed on a range of topics including techniques, management and energy conservation in the dairy industry. The dairy industry has been a chief contributor to the manufacturing capacity in many countries. In addition to pasteurized milk, whey protein concentrates and simple curd to specialty probiotic dairy drinks, there are many more new milk-based products in the market, and this is likely to grow further with innovative products ideas tried in the dairy sector. There are several books on dairy processing and technologies. However, this book, Novel Dairy Processing Technologies: Techniques, Management and Energy Conservation, is not just to stand with the crowd as it has a foremost distinction by dealing with various novel techniques of food processing that have emerged during the past five decades. This also makes the book equally useful for a food technologist. Although the book is not a text book, it would be highly useful for university-level education in food/dairy science and technology. It is important to mention that this book covers novel processing technologies in the dairy sector, such as: Ohmic heating, microwave-assisted processing, hybrid technology, and osmotic dehydration. Products like Kulfi, which is an Indian frozen speciality, has found a unique place in the book. Probably looking into the global importance of food safety, the editors have touched on all relevant topics, such as food management systems, hurdles in the dairy industry, allergens, etc. Energy conservation and energy audits are aptly covered in the book. The book is a nice bouquet of various timely topics that have relevance and significance for a modern food or dairy technologist. I am also pleased to notice that most of the authors are energetic youths, emerging on the horizon of food and dairy research. I appreciate the publisher and editors for this endeavor. Ashutosh Upadhyay, PhD Associate Professor (Food Science and Technology) National Institute of Food Tech. Entrepreneurship & Management (NIFTEM), Plot No. 97, Sector 56, HSIIDC Industrial Estate Kundli, District Sonipat, Haryana – 131028, India Mobile: +91-9034022694 E-mail: email@example.com FOREWORD 3 BY VIJENDER MISHRA Milk is nature's perfect food; it only lacks iron, copper, and vitamin C, and it is highly recommended by nutritionists for building a healthy body. New technologies have emerged in processing milk. To enlighten the reader, the processing of milk by novel techniques, solutions to different hurdles, management, and conservation of energy in the dairy sector have been emphasized in the book. This book is divided into four parts: Part I: Application of Novel Processing Technologies in the Dairy Industry; Part II: Novel Drying Techniques in the Dairy Industry; Part III: Management Systems and Hurdles in the Dairy Industry; Part IV: Energy Conservation: Opportunities in the Dairy Industry. It is nearly impossible to have milk with no microorganisms, even with the most ideal sanitation condition of animals or handlers. It has been found that the thermal treatment of milk leads to the preservation of physiological properties of milk. The most common thermal treatments used by the dairy industry are pasteurization and sterilization. This book focuses on the technology of ohmic heating for milk pasteurization. This book discusses the overview of commercial thermal, non-thermal technologies and hybrid technologies for milk pasteurization. There are non-thermal technologies like pulse light, irradiation, ultra violet treatment etc., that can be used in combination with other technologies for the processing of milk and milk products. This hybrid technology can act as a potential area of research with multiple benefits, such as extended shelf life, reduced energy cost, reduced heat treatment, and better organoleptic and sensory properties. The book also describes the different aspects of food safety management used in a dairy processing unit. In the first section, the need of food safety management system is discussed, followed by risk analysis and different critical control points used in various dairy products that are discussed along with the benefits of FSMS. Another new technology is microwave processing, which has several advantages as compared to the conventional methods used for thermal processing of milk. It can afford new challenges for shelf life extension with better quality retention, microbial stable product, and energy efficiency. The book also focuses on recent advances in microwave-assisted thermal xxiv Foreword 3 by Vijender Mishra processing of milk and the effects of microwaves on microbiological, physicochemical, and organoleptic properties of processed milk and milk products. Technological advances in value addition and standardization of the products have been reported, but a well-established process for mechanized production has been recommended in the book for obtaining a uniform quality nutritious product, produced under hygienic conditions. Vijendra Mishra, PhD Dean (Student Welfare) Associate Professor (Microbiology) Department of Basic and Applied Sciences National Institute of Food Tech. Entrepreneurship & Management (NIFTEM), Plot No. 97, Sector 56, HSIIDC Industrial Estate Kundli, District- Sonipat, Haryana – 131028, India E-mail: firstname.lastname@example.com March 2017 WARNING/DISCLAIMER PLEASE READ CAREFULLY The goal of this volume, Novel Dairy Processing Technologies: Techniques, Management, and Energy Conservation, is to guide the world community on how to efficiently manage the technology available for different processes in dairy engineering. The editors and the publisher have made every effort to make this book as accurate as possible. However, there still may be grammatical errors or mistakes in the content or typography. Therefore, the contents in this book should be considered as a general guide and not a complete solution to address any specific situation. The editors and publisher shall have neither liability nor responsibility to any person, organization, or entity with respect to any loss or damage caused, or alleged to have caused, directly or indirectly, by information or advice contained in this book. Therefore, the purchaser/reader must assume full responsibility for the use of the book or the information therein. The mention of commercial brands and trade names are only for technical purposes. It does not mean that a particular product is endorsed over another product or equipment not mentioned. The editors and publisher do not have any preference for a particular product. All weblinks that are mentioned in this book were active at the time of publication. The editors and the publisher shall have neither liability nor responsibility if any of the weblinks are inactive at the time of reading of this book. The information in this book is not meant for legal use; the information herewith is meant to facilitate clear and smooth communication among the professionals in bioengineering and biology. ABOUT THE SENIOR EDITOR-IN-CHIEF Megh R Goyal, PhD, PE Retired Professor in Agricultural and Biomedical Engineering, University of Puerto Rico, Mayaguez Campus Senior Acquisitions Editor, Biomedical Engineering and Agricultural Science, Apple Academic Press, Inc. Megh R. Goyal, PhD, PE, is a Retired Professor in Agricultural and Biomedical Engineering from the General Engineering Department in the College of Engineering at University of Puerto Rico–Mayaguez Campus; and Senior Acquisitions Editor and Senior Technical Editor-in-Chief in Agriculture and Biomedical Engineering for Apple Academic Press Inc. He has worked as a Soil Conservation Inspector and as a Research Assistant at Haryana Agricultural University and Ohio State University. He was the first agricultural engineer to receive the professional license in Agricultural Engineering in 1986 from the College of Engineers and Surveyors of Puerto Rico. On September 16, 2005, he was proclaimed as "Father of Irrigation Engineering in Puerto Rico for the twentieth century" by the ASABE, Puerto Rico Section, for his pioneering work on micro irrigation, evapotranspiration, agroclimatology, and soil and water engineering. During his professional career of 45 years, he has received many prestigious awards. A prolific author and editor, he has written more than 200 journal articles and textbooks and has edited over 50 books. He received his BSc degree in engineering from Punjab Agricultural University, Ludhiana, India; his MSc and PhD degrees from Ohio State University, Columbus; and his Master of Divinity degree from Puerto Rico Evangelical Seminary, Hato Rey, Puerto Rico, USA. Readers may contact him at: email@example.com. ABOUT CO-EDITOR ANIT KUMAR Anit Kumar is PhD research scholar in the Department of Food Science and Technology at the National Institute of Food Technology Entrepreneurship and Management, Kundli, Haryana, India. He has reviewed research articles and review papers for the Journal of Food Science and Engineering and Nutrition and Food Science. He is a member of the Indian Dairy Association. He has working experience in the dairy and mango industry and also worked as a research scholar (Junior Research Fellow) at NIFTEM, Kundli, India, on the topic "Effect of microfluidization on the quality of fruit flavor and low fat yoghurt". He has also appeared on the NIFTEM YouTube where he demonstrated pedagogical and presentation skills through short films on the making process of patties, vanilla pastry, and puff khari. He has received the best organizer award as a convener for NIFTEM Sports League at NIFTEM, Haryana, India. He completed his Bachelor of Technology in Food Process Engineering from SRM University, Chennai, India, and his Master of Technology in Food Engineering and Technology from SLIET, Punjab, India. During his undergraduate days, his aptitude in the study of machine designs to improve the production and processing of food led him to work on a five-month project in the dairy industry that was oriented toward the evaluation of process flow parameters. During his Master's thesis project, he worked upon improving the design of automatic 'pakoda' (an Indian snack) making machine. The project was intended to increase the overall hygiene of the food product while maintaining the taste. He qualified GATE-2011 in XE-Food Technology and ICAR-NET 2015 in Food Technology. He has published several research articles and review papers in different international and national journals. He has also written several book chapters for different books. He has presented several oral and poster presentations at different international and national conferences. He received a best poster award as a co-author of "Enhancing quality of sugarcane juice: A non-thermal approach" at an international conference, "Food Value Chain: Innovations and Challenges—2016," held xxx About Co - Editor Anit Kumar at NIFTEM, Haryana, India, during March, 2016. He also received third position among all the participants as a co-author of "Hybrid drying of onion slices using low pressure superheated steam and vacuum drying" at a national conference, "Technologies in Sustainable Food System—2016" held at SLIET, Punjab, India, during October, 2016. ABOUT CO-EDITOR ANIL K. GUPTA Anil K. Gupta, PhD, is the sole owner of AG Family Dentistry, LLC, in Alexandria, Louisiana. He was previously a Medical Technologist at Huey P. Long Hospital, Pineville, Louisiana. Dr. Gupta, after completing his PhD (1994) from Haryana Agricultural University, worked in TERI (TATA Energy Research Institute, India) as a research associate, where he published several papers on soil and water. After coming to US in 1995, he retrained himself as a Medical Technologist. Dr. Gupta started working at the Huey P. Long Hospital, Pineville, Louisiana (USA), as a Medical Technologist in 1998 and worked for about ten years. While his stay there, Dr. Gupta decided to go to direct patient care and went to dental school for five years. After graduating in 2014, he worked with a dentist for a year and then opened his own practice in June 2015. Today, Dr. Gupta is a proud owner of a dental practice, which is reaching new heights. OTHER BOOKS ON AGRICULTURAL & BIOLOGICAL ENGINEERING BY APPLE ACADEMIC PRESS, INC. Management of Drip/Trickle or Micro Irrigation Megh R. Goyal, PhD, PE, Senior Editor-in-Chief Evapotranspiration: Principles and Applications for Water Management Megh R. Goyal, PhD, PE, and Eric W. Harmsen, Editors Book Series: Research Advances in Sustainable Micro Irrigation Senior Editor-in-Chief: Megh R. Goyal, PhD, PE Volume 1: Sustainable Micro Irrigation: Principles and Practices Volume 2: Sustainable Practices in Surface and Subsurface Micro Irrigation Volume 3: Sustainable Micro Irrigation Management for Trees and Vines Volume 4: Management, Performance, and Applications of Micro Irrigation Systems Volume 5: Applications of Furrow and Micro Irrigation in Arid and Semi-Arid Regions Volume 6: Best Management Practices for Drip Irrigated Crops Volume 7: Closed Circuit Micro Irrigation Design: Theory and Applications Volume 8: Wastewater Management for Irrigation: Principles and Practices Volume 9: Water and Fertigation Management in Micro Irrigation Volume 10:Innovation in Micro Irrigation Technology Book Series: Innovations and Challenges in Micro Irrigation Senior Editor-in-Chief: Megh R. Goyal, PhD, PE • • Micro Irrigation Engineering for Horticultural Crops: Policy Options, Scheduling and Design Micro Irrigation Management: Technological Advances and Their Applications xxxiv Other Books on Agricultural & Biological Engineering • • Micro Irrigation Scheduling and Practices Performance Evaluation of Micro Irrigation Management: Principles and Practices Potential of Solar Energy and Emerging Technologies in Sustainable Micro Irrigation Principles and Management of Clogging in Micro Irrigation Sustainable Micro Irrigation Design Systems for Agricultural Crops: Methods and Practices Engineering Interventions in Sustainable Trickle Irrigation: Water Requirements, Uniformity, Fertigation, and Crop Performance • • • • Book Series: Innovations in Agricultural & Biological Engineering Senior Editor-in-Chief: Megh R. Goyal, PhD, PE • • • • • • • • • • • • • • • • Dairy Engineering: Advanced Technologies and Their Applications Developing Technologies in Food Science: Status, Applications, and Challenges Engineering Interventions in Agricultural Processing Engineering Practices for Agricultural Production and Water Conservation: An Inter-disciplinary Approach Emerging Technologies in Agricultural Engineering Flood Assessment: Modeling and Parameterization Food Engineering: Emerging Issues, Modeling, and Applications Food Process Engineering: Emerging Trends in Research and Their Applications Food Technology: Applied Research and Production Techniques Modeling Methods and Practices in Soil and Water Engineering Processing Technologies for Milk and Dairy Products: Methods Application and Energy Usage Soil and Water Engineering: Principles and Applications of Modeling Soil Salinity Management in Agriculture: Technological Advances and Applications Technological Interventions in the Processing of Fruits and Vegetables Technological Interventions in Management of Irrigated Agriculture Engineering Interventions in Foods and Plants Other Books on Agricultural & Biological Engineering • • • • • xxxv Technological Interventions in Dairy Science: Innovative Approaches in Processing, Preservation, and Analysis of Milk Products Novel Dairy Processing Technologies: Techniques, Management, and Energy Conservation Sustainable Biological Systems for Agriculture: Emerging Issues in Nanotechnology, Biofertilizers, Wastewater, and Farm Machines State-of-the-Art Technologies in Food Science: Human Health, Emerging Issues and Specialty Topics Scientific and Technical Terms in Bioengineering and Biological Engineering EDITORIAL Apple Academic Press Inc., (AAP) is publishing various book volumes on the focus areas under the book series titled Innovations in Agricultural and Biological Engineering. Over a span of 8 to 10 years, Apple Academic Press Inc., will publish subsequent volumes in the specialty areas defined by American Society of Agricultural and Biological Engineers (<asabe. org>). The mission of this series is to provide knowledge and techniques for agricultural and biological engineers (ABEs). The series aims to offer high-quality reference and academic content in agricultural and biological engineering (ABE) that is accessible to academicians, researchers, scientists, university faculty, and university-level students and professionals around the world. The following material has been edited/ modified and reproduced below [From: Goyal, Megh R., 2006. Agricultural and biomedical engineering: Scope and opportunities. Paper Edu_47 Presentation at the Fourth LACCEI International Latin American and Caribbean Conference for Engineering and Technology (LACCEI' 2006): Breaking Frontiers and Barriers in Engineering: Education and Research by LACCEI University of Puerto Rico – Mayaguez Campus, Mayaguez, Puerto Rico, June 21 – 23]: WHAT IS AGRICULTURAL AND BIOLOGICAL ENGINEERING (ABE)? "Agricultural Engineering (AE) involves application of engineering to production, processing, preservation and handling of food, fiber, and shelter. It also includes transfer of technology for the development and welfare of rural communities", according to <isae.in>. "ABE is the discipline of engineering that applies engineering principles and the fundamental concepts of biology to agricultural and biological systems and tools, for the safe, efficient and environmentally sensitive production, processing, and management of agricultural, biological, food, and xxxviii Editorial natural resources systems", according to <asabe.org>. "AE is the branch of engineering involved with the design of farm machinery, with soil management, land development, and mechanization and automation of livestock farming, and with the efficient planting, harvesting, storage, and processing of farm commodities", definition by: <http://dictionary.reference.com/browse/agricultural+engineering>. "AE incorporates many science disciplines and technology practices to the efficient production and processing of food, feed, fiber and fuels. It involves disciplines like mechanical engineering (agricultural machinery and automated machine systems), soil science (crop nutrient and fertilization, etc.), environmental sciences (drainage and irrigation), plant biology (seeding and plant growth management), animal science (farm animals and housing) etc.," by <http://www.ABE.ncsu.edu/academic/agricultural-engineering.php>. According to https://en.wikipedia.org/wiki/Biological_engineering: "BE (Biological engineering) is a science-based discipline that applies concepts and methods of biology to solve real-world problems related to the life sciences or the application thereof. In this context, while traditional engineering applies physical and mathematical sciences to analyze, design and manufacture inanimate tools, structures and processes, biological engineering uses biology to study and advance applications of living systems." SPECIALTY AREAS OF ABE Agricultural and Biological Engineers (ABEs) ensure that the world has the necessities of life including safe and plentiful food, clean air, and water, renewable fuel and energy, safe working conditions, and a healthy environment by employing knowledge and expertise of sciences, both pure and applied, and engineering principles. Biological engineering applies engineering practices to problems and opportunities presented by living things and the natural environment in agriculture. BA engineers understand the interrelationships between technology and living systems, have available a wide variety of employment options. The <asabe.org> indicates that "ABE embraces a variety of following specialty areas". As new technology and information emerge, specialty areas are created, and many overlap with one or more other areas. Editorial xxxix 1. Aquacultural Engineering: ABEs help design farm systems for raising fish and shellfish, as well as ornamental and bait fish. They specialize in water quality, biotechnology, machinery, natural resources, feeding and ventilation systems, and sanitation. They seek ways to reduce pollution from aquacultural discharges, to reduce excess water use, and to improve farm systems. They also work with aquatic animal harvesting, sorting, and processing. 2. Biological Engineering applies engineering practices to problems and opportunities presented by living things and the natural environment. It also includes applications of nanotechnology in agricultural and biological systems. xl Editorial 3. Energy: ABEs identify and develop viable energy sources— biomass, methane, and vegetable oil, to name a few—and to make these and other systems cleaner and more efficient. These specialists also develop energy conservation strategies to reduce costs and protect the environment, and they design traditional and alternative energy systems to meet the needs of agricultural operations. 4. Farm Machinery and Power Engineering: ABEs in this specialty focus on designing advanced equipment, making it more efficient and less demanding of our natural resources. They develop equipment for food processing, highly precise crop spraying, agricultural commodity and waste transport, and turf and landscape maintenance, as well as equipment for such specialized tasks as removing seaweed from beaches. This is in addition to the tractors, tillage equipment, irrigation equipment, and harvest equipment that have done so much to reduce the drudgery of farming. 5. Food and Process Engineering: Food and process engineers combine design expertise with manufacturing methods to develop economical and responsible processing solutions for industry. Also food and process engineers look for ways to reduce waste by devising alternatives for treatment, disposal and utilization. 6. Forest Engineering: ABEs apply engineering to solve natural resource and environment problems in forest production systems and related manufacturing industries. Engineering skills and expertise are needed to address problems related to equipment design and manufacturing, forest access systems design and construction; machine–soil interaction and erosion control; forest operations analysis and improvement; decision modeling; and wood product design and manufacturing. 7. Information and Electrical Technologies Engineering is one of the most versatile areas of the ABE specialty areas, because it is applied to virtually all the others, from machinery design to soil testing to food quality and safety control. Geographic information systems, global positioning systems, machine instrumentation and controls, electromagnetics, bioinformatics, biorobotics, machine vision, sensors, spectroscopy: These are some of the exciting information and electrical technologies being used today and being developed for the future. Editorial xli 8. Natural Resources: ABEs with environmental expertise work to better understand the complex mechanics of these resources, so that they can be used efficiently and without degradation. ABEs determine crop water requirements and design irrigation systems. They are experts in agricultural hydrology principles, such as controlling drainage, and they implement ways to control soil erosion and study the environmental effects of sediment on stream quality. Natural resources engineers design, build, operate and maintain water control structures for reservoirs, floodways, and channels. They also work on water treatment systems, wetlands protection, vertical farming and other water issues. 9. Nursery and Greenhouse Engineering: In many ways, nursery and greenhouse operations are microcosms of large-scale production agriculture, with many similar needs—irrigation, mechanization, disease and pest control, and nutrient application. However, other engineering needs also present themselves in nursery and greenhouse operations: equipment for transplantation; control systems for temperature, humidity, and ventilation; and plant biology issues, such as hydroponics, tissue culture, and seedling propagation methods. And sometimes the challenges are extraterrestrial: ABEs at NASA are designing greenhouse systems to support a manned expedition to Mars! 10. Safety and Health: ABEs analyze health and injury data, the use and possible misuse of machines, and equipment compliance with standards and regulation. They constantly look for ways in which the safety of equipment, materials and agricultural practices can be improved and for ways in which safety and health issues can be communicated to the public. 11. Structures and Environment: ABEs with expertise in structures and environment design animal housing, storage structures, and greenhouses, with ventilation systems, temperature and humidity controls, and structural strength appropriate for their climate and purpose. They also devise better practices and systems for storing, recovering, reusing, and transporting waste products. xlii Editorial CAREER IN AGRICULTURAL AND BIOLOGICAL ENGINEERING One will find that university ABE programs have many names, such as biological systems engineering, bioresource engineering, environmental engineering, forest engineering, or food and process engineering. Whatever the title, the typical curriculum begins with courses in writing, social sciences, and economics, along with mathematics (calculus and statistics), chemistry, physics, and biology. Student gains a fundamental knowledge of the life sciences and how biological systems interact with their environment. One also takes engineering courses, such as thermodynamics, mechanics, instrumentation and controls, electronics and electrical circuits, and engineering design. Then student adds courses related to particular interests, perhaps including mechanization, soil and water resource management, food and process engineering, industrial microbiology, biological engineering or pest management. As seniors, engineering students work in a team to design, build, and test new processes or products. For more information on this series, readers may contact: Ashish Kumar, Publisher and President Sandy Sickels, Vice President Apple Academic Press, Inc. Fax: 866-222-9549 E-mail: firstname.lastname@example.com http://www.appleacademicpress.com/ publishwithus.php Megh R. Goyal, PhD, PE Book Series Senior Editor-in-Chief Innovations in Agricultural and Biological Engineering E-mail: goyalmegh@gmail. com PART I Emerging Processing Technologies in the Dairy Industry CHAPTER 1 TECHNOLOGY OF OHMIC HEATING FOR THE PASTEURIZATION OF MILK ASAAD REHMAN SAEED AL-HILPHY1*, HAIDER I. ALI1, and GHASSAN F. MOHSIN2 Department of Food Science, College of Agriculture, University of Basrah, Basrah City, Iraq 1 Vocational School, Maysan City, Iraq 2 Corresponding author. E-mail: email@example.com * CONTENTS Abstract...................................................................................................... 5 1.1 Introduction....................................................................................... 6 1.2 History of Pasteurization.................................................................. 8 1.3 Milk Pasteurization........................................................................... 8 1.4 Definition of Electricity.................................................................... 9 1.5 Design of Ohmic Milk Pasteurizer................................................. 12 1.6 Effects of Ohmic Heating on Physical Properties of Milk............. 16 1.7 Performance Coefficient of the Processing System........................ 26 1.8 Holding Time of Milk in the Ohmic Pasteurizer............................ 27 1.9 Effect of Ohmic Heating on the Chemical Composition of Milk... 28 1.10 Effects of Ohmic Heating on Physical Properties of Milk............. 31 This chapter includes information from "Al-Hilphy, A. R. S.; Haider, I. A.; Mohsin, G. F. Designing and manufacturing milk pasteurization device by ohmic heating and studying its efficiency. Journal of Basrah Researches (Sciences): Academic Scientific J. (Basrah University Faculty), 2012, 4(38), 1-18", which is an open access article. 4 Novel Dairy Processing Technologies 1.11 Detection of Activity of Alkaline Phosphatase in Milk.................. 32 1.12 Effects of Ohmic Heating on Elimination of Microbes.................. 33 1.13 Effects of Pasteurization Temperature on Milk Bacteriological, Chemical, and Organoleptic Characteristics................................... 35 1.14 Effect of Ohmic Heating on Denaturation of Milk Proteins........... 39 1.15 Future Prospectives and Research Opportunities........................... 40 1.16 Conclusions..................................................................................... 40 Keywords................................................................................................. 41 References................................................................................................ 41 Technology of Ohmic Heating for the Pasteurization of Milk 5 ABSTRACT The best voltage for milk pasteurization by using ohmic heating was 80 V compared with 110, 220 V, both of which were inadequate for pasteurization. Heating at 80 V was safer and inexpensive as it required less power (80 V) in contrast with higher voltages (110–220 V) and less dangerous. Voltage of 80 V does not change milk color to brownish as it was noticed at 110– 220 V and undesirable smells were not present. Heating at 80 V did not cause fouling or precipitation of deposits on electrodes compared to 110–220 V. The best electrical conductivity was at 80 V as there were no deposits on the electrodes. The practical temperature of milk was stable because of the thermal valve, which controls the temperature at 72°C. The electric conductivity and current were increased with increasing temperature in ohmic heating at 220, 110, and 80 V while these were decreased with the increase of temperature at 220 V. The thermal conductivity and thermal diffusivity were increased with the increase of temperature at all voltages in the ohmic heating and high time short temperature (HTST). The viscosity of milk and its density were decreased with the increase of temperature at all voltages in the ohmic heating and HTST. The period of keeping milk in the device was decreased with the increase of voltage in the ohmic heating, which was less than HTST. At 80 V of treatment, the highest coefficient of performance was 0.80, compared with 220, 110 V, with performance coefficient of 0.49 and 0.76, respectively. The percentages of protein, lipid, lactose, ash, and humidity in raw milk were 3.6, 3.7, 5.02, 0.68, and 87.0%, respectively. These values at 80 V were 3.5, 3.6, 6.2, 0.69, and 85.9%, respectively; and at 110 V were 3.54, 3.6, 6.9, 0.69, and 85.2%, respectively; and at 220 V were 3.5, 3.6, 7.1, 0.73, and 85.0%, respectively, and in HTST were 3.57, 3.7, 6.0, 0.71, and 87.0%, respectively. The percentage of acidity in raw milk was 0.15% and was 0.14, 0.14, 0.13, and 0.15%, respectively, for ohmic heating at 220, 110, 80 V, and HTST. The pH prior the pasteurization was 6.6 compared to 6.7, 6.8, 6.8, and 6.8 after the pasteurization by ohmic heating at 220, 110, 80 V, and HTST treatment, respectively. The phosphatase enzyme test gave positive results in raw milk and negative one in pasteurized milk treated either by ohmic heating on all voltages and HTST. The clot on boiling test and turbidity test gave negative results for raw milk. The microbiological results of pasteurized milk by ohmic heating showed no colonies in total 6 Novel Dairy Processing Technologies count bacteria, coli form, Staph-110, yeasts, and molds. Milk treated by HTST pasteurization had bacteria while bacteria were absent. The shelflife study of pasteurized milk by ohmic heating at 4°C for 15 days showed no change in pH and acidity. The results also showed no colonies in bacterial total count bacteria, coli form, staph-110, yeasts, and molds. However, pasteurized milk by both methods (ohmic and HTST) could only be stored for 72 h at room temperature. The HTST treated milk could be stored for 8 days at 4°C for 8 days. 1.1 INTRODUCTION Since dairy products contain most of the nutrients needed to build the human body, milk contains a number of nutrients such as carbohydrates, fats, proteins, minerals, and vitamins besides water. These nutrients distinguish milk to have a variety of nutritional values resulting in highest biological value in comparison with other foods.6 It is nearly impossible to have milk with no microorganism even though there is availability of ideal healthy conditions and sanitation of animals or milkman. Contamination includes mixed microorganisms. Part of it is harmful to human health as these produce lactic acid. Others are harmful because these contribute in transporting disease or produce poisons. Therefore, milk can be a source of spreading diseases. It has been found that the thermal treatment to the milk leads to the preservation of physiological properties of milk. Also, the milk without adequate treatments in the dairy industry is not of good quality.8 The most common thermal treatments used by dairy industry are pasteurization and sterilization. The common properties of pasteurization of milk focus on two aspects: • • Health aspect, which eliminates pathogenic organisms in milk, eliminates 95–99% of bacteria in milk as well as 100% of yeasts and molds due to milk exposition to different temperatures at different times. The second aspect increases the ability of preserving milk due to the elimination of pathogenic organisms.2 United States Food and Drug Administration (USFDA) has introduced standards for pasteurizing milk and milk products that includes treating Technology of Ohmic Heating for the Pasteurization of Milk 7 and exposing the milk to: 62.8°C for 30 min, 71.6°C for 15 min, 88.4°C for 0.1 s, 95.6°C for 0.05 s, and 100°C for 0.01 s.27 Al-Dehan2 indicated three methods of milk pasteurization: • • • Batch pasteurization: In this type of pasteurization, milk is exposed to 62.8°C for a period not less than 30 min. The treatment is done in batches and is also called dock (tank) method. High temperature short time (HTST): Milk is exposed to 72°C for 15 s. Vacuums pasteurization: Milk is exposed to different thermal treatments under vacuum. The objective is to get rid of bad smell of some dairy products. Milk is exposed to 90.5–96.1°C under vacuum pressure. There are other methods of pasteurization such as: • • • • Continuous-flow system: Milk is allowed to flow through pipes and at the same time it is exposed to different thermal treatments for half an hour and the length of pipes ensures adequate thermal treatment. Infra-red treatment: Milk is allowed to flow through horizontal rustproof iron pars that are exposed to infrared rays until temperature rises to 85°C for a desired period.49 Microwave: Milk is exposed to the microwave energy in batches to have a temperature of 72°C for 15 s.4 Use of solar energy.1 The ohmic heating to treat foods is being widely used throughout the world, due to low requirements of electricity and the need of small space in comparison with traditional methods.75 Also ohmic heating has shown benefits over other methods including coordination and regulation in heating and energy efficiency by giving it a shortcut in the design and lack of phenomenon of slowdown.74 The use of electrical technology in preparing food gives clean and efficient energy suitable to environment compared with classical methods.81 Recently research studies have focused on the design and development of efficiency of ohmic heating for food and sterilization at Mars exploration vehicle.41,42 This chapter focuses on the technology of ohmic heating for milk pasteurization. 8 1.2 Novel Dairy Processing Technologies HISTORY OF PASTEURIZATION The term "Pasteurization" was named due to famous French chemical scientist Lewis Pasteur (1822–1895), who had established manufacturing microbial science rules. During the years 1864–1865 and 1871–1872, Pasteur had treated alcoholic drinks by 50–60°C to eliminate unwanted fermenting microbes.17 He concluded that milk fermentation was similar to alcoholic fermentation, as they shared the same fermenting factor, in growth of unwanted microbes. In 1880, he started the use of pasteurizing devices to heat the milk at the temperature range of 60–70°C without determining the retention time. However, he rapidly paid attention to the fact that milk pasteurized with no retention time could cause diseases to consumers transmitted by milk. At the end of that century, scientists started the use of pasteurizing devices using pipes to seize milk at a pasteurization temperature. They found that suitable temperature was 60°C for 20 min for milk free from Mycobacterium tuberculosis bacteria.27 In 1935, it was found that pasteurized milk had alkaline phosphatase enzyme as an indicator so that pasteurization was not efficient as it inhibits this enzyme.21 HTST method is an effective method,27 as it heats every molecule of milk to the desirable temperature (71.1°C for 15 s). This method eliminates 95–99% of bacteria in milk and extends its storage life remarkably.60 Pasteurization has been practically used for decades as a method to preserve liquid milk for longer periods.48,66,86 Pasteurizing milk by HTST method can extend ideal preserving period for six months without fridge,66 though some changes may occur during storage period as gelatin formation. 1.3 MILK PASTEURIZATION Milk pasteurization is a thermal treatment to each molecule of milk at a temperature less than 100°C. It can be done either by slow method as temperature rises between 62 and 65°C for 30 min or by HTST method with a temperature of 71.8°C for 15–40 min or by flash heating (85–90°C for 1–4 s) or exposing milk to a temperature between 94°C and 100°C for 0.01–0.1 s.25,50 There are other methods like: microwave with different batches3 or solar heating.1 Technology of Ohmic Heating for the Pasteurization of Milk 1.4 9 DEFINITION OF ELECTRICITY Electricity consists of concepts less popular than electromagnetic field and electromagnetic induction. Electrical power is more flexible type of power source at low cost in comparison with other sources of energy. The word electricity consists of two Persian words; "kah" means straw and "rby" means magnetic and electricity means "Kahrman" (amber) in Persian. The Latin word is "electricus," which means like amber. The latest word also taken from Greek word ἤλεκτρον (electron) also means amber.12 This association gives two words "electric" and "electricity," which was first shown by Thomas Brown book "Common Mistakes" in Latin "Pseudodixa Epidemica" edited in 1646.19 Although early 19th century had shown fast development in electricity science, yet the late period of this century showed most of the developments in electrical engineering. Therefore, electricity changed from the scientific curiosity to main indispensable tool in modern life and the driving force to second industrial revolution. This rapid development is owed to the work of renowned scientists, such as Nikola Tesla, Thomas Edison, Otto Bly, George Westinghouse, Ernst Von Siemens, Alexander Graham Bell, Lord William Watson, and Barron Kelvin I. Electricity is very flexible type of energy, as it suits any type of use.16,68,94 In the 18th century, a German scientist, George Simon Ohmic, drafted a law called Ohmic's law. During his studies, Ohmic proved that the electric current is directly proportional to the voltage on the circuit and the relationship of the current and the voltage in the circuit is linear as well as power is inversely proportional to the value of the total resistance of the circuit as shown in Figure 1.1. FIGURE 1.1 The relationship between the current and voltage. Ohmic law states that the current (I) flowing in the resistance is directly proportional to the applied voltage (V) and inversely to the resistance (R) as described by the following equation:71 10 Novel Dairy Processing Technologies I = V/R (1.1) The different forms of Ohmic formula9,38 are: I = V/R (1.2) R = V/I and V = I × R (1.3) It can be concluded that name and mechanical technique of ohmic heating was taken from Ohmic's law depending on the voltage difference and resistance. The success of using electricity in food processing was developed in 19th century, when milk pasteurization was introduced.30 This method of pasteurization is called electropure process. In 1938, five states of USA used method of pasteurization and served about 5000 consumers.52 In the 20th century, milk was pasteurized by passing electricity through parallel plates. During the past two centuries, new and developed materials and different designs of ohmic heating technique have been introduced. Great Britain Electricity Council (GBEC) granted the patent on continuous flow in ohmic heating and authorized its use to APV Baker Company.84 This technique was left as a result of high cost.23 Finally ohmic heating got more attention because of best quality of the product compared to other classical techniques.18,44,58,75 Ohmic heating technique has also been called Joule or resistive heating. In this method, electric current passes through the food material causing a homogeneous distribution of heat inside the food.35,46,81 The fast work, homogenized heat and less loss of food vitamins are characteristics of ohmic method.91,92,97 Increase in homogeneous heat of food gives well-accepted products.27 The advantages of this method are: simple to use, high-energy efficiency, and low cost compared to microwave and radio vibration methods.31,44,51 Processing of foods by electric technique is environment friendly.43,81 The use of ohmic heating gives a product of acceptable quality.47 There are several precautions to be taken into consideration while designing the pasteurization device. One of these precautions is the ability to heat to a recommended pasteurization temperature, as the temperature should be chosen before designing the heat exchanger. Further, pasteurization temperature depends on the seizing period and pasteurization of nonnaturalized milk. Therefore, the heat exchanger should be able to heat the milk to a temperature around 73–74°C, which is clearly greater than the desirable pasteurization temperature.27 Other precaution is the ability to keep the product at a pasteurized temperature to get rid of pathogenic Technology of Ohmic Heating for the Pasteurization of Milk 11 microbes, inhibition of alkaline phosphatase enzyme, cooling ability, controlling pasteurization temperature, working accuracy, and the ability to have minimum changes in chemical and organoleptic properties of milk, pasteurization device free from microbial and chemical contamination.27 The design of ohmic heating technique must be taken into consideration: type of product to be pasteurized, its characteristics and properties, electrical conductivity, and heating coefficient of this substrate.47 Ohmic heating device by Ayadi et al.11 consisted of five ohmic cells in the form of rectangular channels (cell length of 240 mm, thickness of 15 mm, and width of 75 mm): three cells for heating and the other two for electrical isolation. Japan started production of ohmic heating system in 1995,53 while Yanagiya developed ohmic heating system type MINI-J with titanium poles in 1999.53 Ghnimi et al.31 designed an ohmic heating system (Fig. 1.2) with feed pump type PCM Moineau, vibratory tank and two heat exchangers (the first from pipe type double cooling and the second was an ohmic cell for heating). Kong et al.45 designed ohmic heating device consisting: ohmic heating unit that included voltage exchanger device and pores from rust resistance steel and teflon pipe; and data collection system consisting of a digital conductivity meter and thermocouple. Samaranayake and Sastry72 indicated that the use of poles of stainless steel is one of the very active electrochemical substances during ohmic heating to resist all pH values. Stirling87 and Berthou et al.15 used titanium poles covered with platinum or Raytheon to inhibit electrical that occurs during alternating current with a low frequency (50 or 60 Hz). Reznik70 used stainless steel poles for a frequency >100 Hz or poles from graphite. Reznik69 added that electrolyte between electrical pole and the product could prevent the product from contamination. FIGURE 1.2 Ohmic heating system. 12 1.5 Novel Dairy Processing Technologies DESIGN OF OHMIC MILK PASTEURIZER Ohmic milk pasteurizer (Figs. 1.3 and 1.4) consists of raw milk tank (double jacket of 25 L capacity made of stainless steel), feed pump of plastic of 70 W power, heat exchanger of 120 cm in length and 1.25 cm diameter, heating tube made of heat resisting Teflon of 36 cm length and 5 cm diameter; and consists of electrodes made of stainless steel that can heat the milk at three different voltages 80, 110, and 220 V. FIGURE 1.3 Layout of milk ohmic pasteurizer.5 FIGURE 1.4 Image of milk ohmic pasteurizer.5 Technology of Ohmic Heating for the Pasteurization of Milk 13 These electrodes were organized in the tube in a parallel arrangement and the distance between these was of 5.5 cm. The device also includes a holding tube of 4 m in length and 1 cm in diameter; to hold milk for 15 s at 72°C. It also has an electric valve, nonreverse delivery valve and manual valve. The design equations are presented below: Overall heat transfer (U) is calculated as following:25 1 1 X 1 = + + U ha K hb (1.4) where ha, hb, X, and K are heat transfer by convection for hot and cold milk (W/m.°C), pipe thickness and heat transfer by conduction for pipe (W/m2.°C), respectively. DV ρ Re = Nu = Pr = ha D K (1.6) Cp µ (1.7) K N u = 1.62 ( Re Pr h u = 1.62 (1.5) µ D 0.33 ) L K D ( Re Pr )0.33 D L (1.8) (1.9) where Re, Nu, Pr, µ, D, Cp, and L are Reynolds number, Nusslet number, Prandtl number, milk viscosity (Pa.s), pipe diameter, milk specific heat, and pipe length (m), respectively. Physical properties of milk were taken at mean bulk temperature. Mean logarithmic difference of temperatures ∆Tm is calculated from the following equation: ∆Tm = ( Thi − Tco ) – (Tho− Tci ) ln( Thi − Tco ) Tho − Tci (1.10) 14 Novel Dairy Processing Technologies q = mcp (Tco – Tci) (1.11) q = U A ∆Tm (1.12) q / U ∆Tm (1.13) A = πDL (1.14) L = A / πD (1.15) where q, Thi, Tho, Tco, and Tci are heat energy, hot milk temperature entering into heat exchanger (°C), hot milk temperature exiting from heat exchanger (°C), heated milk temperature exiting from heat exchanger and going to heating unit (°C), and cold milk temperature entering into heat exchanger (°C). Ratio of regeneration heat in the heat exchanger was 65%. Ratio of regeneration heat is calculated from the following equation: εh = Tco − Tci × 100 Thi − Tci (1.16) Milk temperature that exit from ohmic heating unit is calculated from the following equation:14 aT + b =e aTo + b aπ d c L m c p 2 a= ∆V d c σ o m n 4 −U 2 b= d c ∆V σ o +U 4 (1.17) (1.18) (1.19) where (∆V), σo, dc, and L are voltage progress on the long of heating tube (V/m), electrical conductivity for milk at temperature of 0°C, heating tube diameter (m2), and heating tube length (m), respectively. mn is the constants related to electrical conductivity56 according to the following equation: σL = σo (1 + mn T) (1.20) Technology of Ohmic Heating for the Pasteurization of Milk 15 where σL, m•, and U are milk electrical conductivity (S/m), mass flow rate of milk (kg/s) and over all heat transfer of milk (W ̸m2.°C) depends on outside area of heating tube (m2), respectively. q = ho A (Tins – Ta) ho = q A (Tins. − Ta ) (1.21) (1.22) where q, ho, Tins, Ta, and A are lost heat energy (W), heat transfer by convection between insulator and ambient (W ̸m2.°C), insulator temperature (°C), ambient temperature (°C), and insulator area (m2), respectively. Heat transfer coefficient by convection (hi) is calculated using Nusslet number as follows: N Nu = hi D K (1.23) where NNu, K, and D are Nusselt number, heat transfer coefficient by conduction (W ̸m.°C), and diameter (m), respectively. Mean temperature of milk for determination of physical and heat properties of milk is calculated as follows: Tin + Tw 2 (1.24) D 0.085 N Re × N Pr × L µb 0.14 ( ) = 3.66 + D µw 1 + 0.045 N Re × N Pr × L (1.25) Tf = N Nu where µb and µw are milk viscosity (pa.s), and milk viscosity at mean temperature (pa.s.), respectively. q = hi A (Tin – Tw) (1.26) where Tw and Tin are milk temperature entering pipe (°C) and milk temperature exit of pipe (°C), respectively. q= V 2 . Aσ L L (1.27) 16 Novel Dairy Processing Technologies U= r3 + r1hi r3ln ( ) r2 KA r1 1 r r3ln 3 r 2 1 + + KB ho (1.28) where r1, r2, r3, KA, and KB are internal radius of cylinder (m), external radius of cylinder (m), total radius with insulator (m), and heat transfer coefficient by (W ̸m.°C), respectively. On the other hand, the length of holding tube is calculated by the following equation:89 LH = V= 4V π D2 QHT 3600 η (1.29) (1.30) where Q, HT, LH, D, V, and η are mean flow rate of milk (m3/h), holding time (s), holding tube length (m), internal diameter of pipe (m), milk volume during Q and HT, and efficiency factor (= 0.85), respectively. 1.6 EFFECTS OF OHMIC HEATING ON PHYSICAL PROPERTIES OF MILK 1.6.1 ELECTRICAL CONDUCTIVITY Electrical conductivity is one of the important factors which affect the success of ohmic heating technique. Conductivity increases with mineral content, acids, and moisture; and reduces with fat and alcohol present in the food. Electrical conductivity can be measured based on equations by Wang and Sastry96 and Icier et al.:36 σ= IL VA (1.31) where I = current (A), L = distance between poles (m), V = voltage (V), A = area (m2), and σ = the electrical conductivity (S/m). The ability of material to conduct electricity is called specific resistance, which is known as solution pole resistance (R, Ohms) for 1 cm in Technology of Ohmic Heating for the Pasteurization of Milk 17 length and 1 cm thickness of sample. The specific conductance is a reciprocal of specific resistance, and it is very low (0.005) for natural milk but it increases for skim milk from infected mammary gland (mastitis) because of high level of sodium and chlorine.8 However, Alnimer6 indicated that fresh milk conductivity ranges from 45 × 104 to 48 × 104 S/m and increases to reach 10–13 × 105 S/m when there is mastitis because of high chloride, which shows an importance of measuring conductivity. Milk has a homogenous electrical conductivity due to enough free water saturated with solved ionic minerals, which makes the milk suitable for ohmic treatment.55 Novy and Zinty54 found that milk conductivity was increased with increase in heat, and was 0.5, 0.65, 0.94, and 1.1 S/m at a temperature of 20, 40, 60, and 80°C, respectively. Figure 1.55 shows that electrical conductivity was increased with increasing milk temperature in the high traditional pasteurization and ohmic heating at 110 and 80 V; while at 220 V, the electrical conductivity was decreased with increasing milk temperature. Also, the Figure 1.5 shows that electrical conductivity at 220 V reached to 0.4 S/m at 22°C then was reduced with increasing temperature till it was 0.25 S/m. Many researchers have found that the electrical conductivity of food products always increases with increasing temperature, food moisture content, and ionic salts by ohmic heating at 220 V, implying that heating is desirable FIGURE 1.5 Milk electrical conductivity under ohmic pasteurizing treatment.5 18 Novel Dairy Processing Technologies for treatment at high moisture content (87%) and ionic salts percentage of 0.7%. The high reduction in the electrical conductivity was because of presence of deposits on the electrodes. Electrical conductivity of foods changes with temperature depending on the food type. In some foods, the electrical conductivity increases with increasing temperature with ohmic heating at 220 V, because the proteins do not denature on the electrodes, but it causes denaturation of whey proteins that is affected by high temperature. The relationship between electrical conductivity at 220 V and milk temperature is a linear equation with an intercept of −0.0028 as shown below: Ec220V = – 0.0028 T + 0.4351 (1.32) Ec110V = + 0.001 T + 0.285 (1.33) Ec80V = + 0.002 T + 0.778 (1.34) However, the relationship between electrical conductivity and temperature at 110 V is linear equation with a positive slope and with a determination coefficient of 0.94. It may be due to reduction of formation of deposits on the electrodes, at low voltage. The electrical conductivity reached 0.8 S/m at 80 V and no fouling occur on the electrodes. Equation 1.34 indicates the relationship between the electrical conductivity and temperature. In the high traditional pasteurization, the electrical conductivity reached to 0.6 S/m at temperature of 22°C then was increased with increasing milk temperature till temperature reached 72°C. This is because a part of moisture content was evaporated from milk that led to increase in concentration of salts in milk, which caused the increase in electrical conductivity. The following equation shows the relationship between electrical conductivity and milk temperature: EcCont = 1 × 10–4 T 2 – 0.0071 T + 0.7405 (1.35) 1.6.2 ELECTRICAL CURRENT Figure 1.6 shows that electrical current was increased with increasing milk temperature at 110 and 80 V, while it was decreased with temperature at 220 V because of formation of fouling on the electrodes.5 Technology of Ohmic Heating for the Pasteurization of Milk FIGURE 1.6 1.6.3 19 Electrical current passing in milk treated by milk ohmic pasteurizer.5 MILK TEMPERATURE Figure 1.7 shows that milk temperature (T) was increased with increasing heating time (t). The required heating time for temperature to reach 72°C was 6.65, 6.15, 5.15, and 7.65 min for ohmic heating at 80, 110, 220 V, FIGURE 1.7 Effects of heating time on milk temperature for ohmic pasteurizer.5 20 Novel Dairy Processing Technologies and high traditional pasteurization, respectively.5 Investigators developed following empirical equations for prediction of milk temperature for ohmic pasteurizer: T80V = –0.6246t2 + 11.799t + 21.478 (1.36) T220V = 0.2507t4 – 36.25t3 + 15.095t2 – 6.4339t + 23.288 (1.37) TCont = – 0.0405t + 0.5209t – 1.6774t – 6.6737t + 24.862 (1.38) 4 3 2 T110V = – 0.122t5 + 1.7925t4 – 8.9003t3 + 16.887t2 – 15.958X + 21.989(1.39) 1.6.4 THERMAL CONDUCTIVITY Thermal conductivity of most high moisture foods is nearly similar to that of water. It is an important property that determines thermal transfer through the food during processing and moisture content of food has large impact on the thermal conductivity.65 Figure 1.8 illustrates the relationship between milk thermal conductivity and temperature for ohmic heating at 80, 110, 220 V, and high traditional pasteurization.5 Thermal conductivity was increased with increasing temperature at all voltages and high traditional pasteurization. For example, when milk temperatures were 22, 32, FIGURE 1.8 Milk thermal conductivity for ohmic pasteurizer.5 Technology of Ohmic Heating for the Pasteurization of Milk 21 42, 52, 62, and 72°C, thermal conductivity was 0.55, 0.56, 0.57, 0.58, 0.59, and 0.6 (W/m2.°C), respectively, for ohmic heating at 80 V. The following empirical equations describe the linear relationships between thermal conductivity and temperature: 1.6.5 K80V = 0.001 T + 0.532 (1.40) K110V = 0.001 T + 0.532 (1.41) K220V = 0.001 T + 0.531 (1.42) Kcont = 0.001 T + 0.534 (1.43) MILK VISCOSITY Viscosity is the resistance that liquid offers to movement or flow of its one layer relative to the other. It can also be defined as ratio of cutting resistance to the cutting velocity. It is considered as a tool to monitor the quality of foods at different stage of production. Therefore, it is related to the ability to manipulate the amount of heat used by measuring viscosity, as there is strong relationship between viscosity and heat diffusion. Increase of viscosity hinders the movement of heated membrane and resulted in slowing the heat transfer rate in comparison with low viscosity liquids. Pasteurization at 72°C for 15 s had no effect on milk viscosity.27 Milk viscosity ranged from 1.4 to 2.2 centipoise at 20°C, as it depends on the milk colloidal particles especially proteins and fats. Viscosity is important milk property to control fatty products.6 Figure 1.9 shows that milk viscosity was decreased with increasing temperature for ohmic heating at 80, 110, and 220 V and high traditional pasteurization.5 At 22°C, milk viscosity was 1.75 × 10−3, 1.71 × 10−3, 1.37 × 10−3, and 1.73 × 10−3 pa.s under ohmic heating at 80, 110, and 220 V and high traditional pasteurization, respectively; and it was 2.8 × 10−3, 2.39 × 10−4, 7.84 × 10−4, and 2.8 × 10−4 pa.s, respectively, at temperature of 72°C. Milk viscosity was decreased because of reducing fat clusters with increasing temperature. Fat clusters affect the milk viscosity at a particular temperature. Denaturation of whey proteins is sensitive to high temperatures. Also, there is a damage of Gluten proteins, which are responsible for the collection of fat globules. All these factors led to decrease in viscosity. The following empirical equations describe the relationship between milk viscosity and temperature: 22 Novel Dairy Processing Technologies μ220V = – 2.756 × 10–5 T + 0.002 (1.44) μ80V = – 2.85 × 10–5 T + 0.002 (1.45) μCont = – 2.923 × 10–5 T + 0.002 (1.46) μ110V = 4.312 × 10 T – 6.559 × 10 T + 0.003 –7 FIGURE 1.9 1.6.6 2 –5 (1.47) Effects of temperature on milk viscosity under ohmic pasteurizer.5 MILK DENSITY Density is a mass of the food per unit volume. The specific gravity of milk is the ratio of milk density to the density of water and can be indicator of adulteration of the milk8 for cattle milk, specific gravity ranges from 1.035 to 1.051. However, specific gravity of mixed milk ranges from 1.030 to 1.035. The density and temperature are negatively related for most milk as compared to water due to the presence of protein and fat in milk. However, density of lactose is not affected significantly.8 Milk specific gravity is the weightage average of specific gravities of its contents. Since the contents are heavily influenced by many factors. The low value of milk specific gravity indicates the addition of water. Measurements are done at temperature of 15.5°C.6 Figure 1.10 shows that milk density was decreased with increasing temperature for all ohmic heating treatments.5 Milk density treated by Technology of Ohmic Heating for the Pasteurization of Milk 23 ohmic heating at 80 V and temperature of 22°C was 1.020 kg/m3. Milk density depends on the content of proteins and fat in milk. If milk fat is reduced, then the density will increase. When milk was pasteurized by ohmic heating at 110 and 220 V, the density was lower than the milk pasteurized by ohmic heating at 80 V and high traditional pasteurization because of heating intensity, which reduces denaturation of whey proteins on the electrodes and led to loss of part of milk proteins. The following empirical equations can be used for the prediction of milk density at different temperatures. FIGURE 1.10 1.6.7 ρ220V = – 0.308T + 1014.395 (1.48) ρ110V = – 0.304T + 1016.674 (1.49) ρ220V = – 0.343T + 1028.114 (1.50) ρcont = – 0.303T + 1023.573 (1.51) Effects of temperature on milk density under ohmic pasteurizer.5 SPECIFIC HEAT It is the quantity of heat energy to rise water temperature by one degree at a constant pressure. It can also be defined as the lost or gained heat of a unit weight of product to reach the preferred temperature without 24 Novel Dairy Processing Technologies changing the state. It is an important part of thermal analysis in food processing or in food manufacturing. Milk specific heat is influenced by moisture content, temperature, and pressure of the milk.7, 22 As specific heat increases with rise of product moisture and gas specific heat at constant pressure is greater than that at constant volume, most engineering applications for food processing use specific heat at constant pressure.24,83 Figure 1.11 shows that specific heat of milk is increased with increase in temperature for all ohmic heating treatments.5 For example, at milk temperature of 22 and 72°C, the specific heat was 3860 and 3890 J/kg.°C, respectively, at ohmic heating of 80 V; however, for traditional pasteurization it reached 3870 and 3900 J/kg.°C, respectively. The following empirical equations indicate the linear relationships between the specific heat and temperature: FIGURE 1.11 Cp 220V = 3835.752 + 0.611 T (1.52) Cp 110V = 3841.651 + 0.611 T (1.53) Cp 80V = 3847.316 + 0.609 T (1.54) Cp cont = 3856.206 + 0.605 T (1.55) Effects of temperature on milk specific heat for ohmic pasteurizer.5 Technology of Ohmic Heating for the Pasteurization of Milk 1.6.8 25 THERMAL DIFFUSIVITY Thermal diffusivity represents the thermal conductivity of food divided by its density and specific heat.83 Thermal diffusion value of food products ranges from 1 × 10−7 to 2 × 10−7 m2/s.83 It can be calculated from the following equation: ∝= K Cp (1.56) where ∝ = the thermal diffusivity [m2/s], k = the thermal conductivity (W/m2.°C), and Cp = the specific heat at constant pressure (J/kg.°C). There were no significant differences in thermal diffusivity among ohmic heating treatments and high traditional pasteurization (Fig. 1.12). Thermal diffusivity of pasteurized milk by ohmic heating at 80, 110, 220 V, and high traditional pasteurization was 1.47 × 10−7, 1.48 × 10−7, 1.483 × 10−7, and 1.47 × 10−7 m2/s, respectively.5 Thermal diffusivity was increased with increase in temperature because of the thermal diffusivity is directly proportional to extrusive thermal conductivity and inversely related with the density and specific heat. Thermal diffusivity can be calculated by the following linear equations: FIGURE 1.12 λ220V = 2.787 × 10–10 T + 1.365 × 10–7 (1.57) λ110V = 2.779 × 10–10 T + 1.362 × 10–7 (1.58) λ80V = 2.803 × 10–10 T + 1.346 × 10–7 (1.59) λcont = 2.736 × 10–10 T + 1.352 × 10–7 (1.60) Milk thermal diffusivity versus temperature for ohmic pasteurizer.5 26 1.7 Novel Dairy Processing Technologies PERFORMANCE COEFFICIENT OF THE PROCESSING SYSTEM System performance coefficient (SPC) is calculated as follows:35 SPC , = Qt Eg where (1.61) Eg = Qt + Eloss = ∑∆VIt (1.62) Qt = mcp (Tf – Ti) (1.63) where m = mass (kg), Tf = final temperature (°C), Ti = primary temperature (°C), Eg = amount of given energy (J) and Qt = the amount of heat taken (J); V = voltage (V), I = current (A), t = time (s), cp = specific heat (J/kg. °C), and Eloss = lost heat (J). It can be observed in Figure 1.13 that the performance factor was decreased with increase in applied voltage. Performance factor reached 0.82 at 80 V then was reduced to 0.7 at 110 V and 0.59 at 220 V because the loss of energy at 220 V was higher than that at 110 and 80 V. Icier and Ilicali35 and Hosain et al.33 stated that increasing applied voltage led to reduction in performance factor. They explained that 0–15% of electric energy provided to ohmic heating system was not used for processing of peach juice and it was considered as loss in energy. They stated that increasing performance factor refers to the reduction in energy loss and most of the electric energy was converted to heat energy at zero energy loss. The maximum value of FIGURE 1.13 Performance coefficient for milk ohmic pasteurizer versus applied voltage.5 Technology of Ohmic Heating for the Pasteurization of Milk 27 performance factor is 1 or 100%. The relationship between performance factor and applied voltage is shown in Figure 1.13:13 η = 2.9264 V−0.299 1.7.1 (1.64) HEATING RATE Heating rate was increased with increase in applied voltage. Increasing voltage means increasing power supplied to the ohmic heating system. The heating rate was 10.9, 11.61, and 13.84°C/min at applied voltage of 80, 110, and 220 V, respectively (Fig. 1.14). The relationship between heating rate and voltage was linear with a coefficient determination of 0.991 as indicated in the following equation: 0.022 V + 9.162= HR FIGURE 1.14 1.8 (1.65) Milk heating rate versus applied voltage for milk ohmic pasteurizer.5 HOLDING TIME OF MILK IN THE OHMIC PASTEURIZER Holding time of milk for the ohmic pasteurizer is calculated as follows: t= ρ ALd W (1.66) 28 Novel Dairy Processing Technologies where t = the holding time (s), ρ = density (kg/m3), A = the area (m2), Ld = the tube length (m), and W = mass flow (kg/s). Figure 1.15 shows the relationship between milk temperature and holding time using ohmic heating at different voltages (80, 110, and 220V). During milk pasteurization by ohmic heating, milk is held every part of pasteurizer for a specific time that is different for each subprocess. The required time for raising milk temperature from 22 to 40°C is 3.96 min for the heat exchanger, and then milk is brought to ohmic heating unit and stays there.5 The required time for reaching milk temperature to 72°C is 1.51 min; and after this milk temperature is reduced to 22°C for a holding time of 0.34 min. Therefore, the total holding time for the ohmic pasteurizer at 80 V is 6.3 min. However, the required time for high traditional pasteurization and ohmic pasteurizing at 80, 110, and 220 V was 11.11, 6.3, 6, and 5.54 min, respectively. FIGURE 1.15 pasteurizer.5 Milk temperatures (heating and cooling) versus holding time for ohmic 1.9 EFFECT OF OHMIC HEATING ON THE CHEMICAL COMPOSITION OF MILK 1.9.1 MILK PROTEINS The quantity of milk deposits depends on type of raw milk, type and intensity of heat treatment. It has been found that deposits increase with heat Technology of Ohmic Heating for the Pasteurization of Milk 29 treatment intensity in any thermal treatments. It is believed that percentage of deposits of milk solids is the residual part of solids that is deposited on the surface of heat exchanger, thus causing fouling. Sandu and Lund73 have discussed theoretical mechanism of milk deposits in details. They suggested the presence of at least two separate interactions in heat-treated milk that contribute to the formation of deposits. • • The first is whey protein denaturation, responsible for smooth protein deposits (smaller particles). Whey protein denaturation plays an important role in the formation of deposits on exchanger surfaces during milk and its products during manufacturing. The second is a decrease of calcium triphosphate that is dissolved with rising temperature, thus resulting in bigger particles. Rakes et al.64 found that formation of deposits within thermal exchanger because whey proteins are much higher, during exposure of milk to the thermal treatment. In dairy factories, deposits are formed at different apparatuses; pasteurization devices or evaporators. Cleaning of these devices is a costly operation, and requires high energy, cleaning materials, and labor.54 Deposits deteriorate the quality of product, because milk cannot be heated to a required temperature during pasteurization.13,82 These deposits reduce heat transfer efficiency and increase the downward pressure.82 Johansson39 indicated that deposits are part of the problems that occur during the use of HTST method in pasteurization as proteins and minerals are deposited on thermal exchanger surfaces. However, Ayadi et al.10 and Pereira et al.61 showed that ohmic heating improves product quality by reducing deposits. Also, hot surfaces in ohmic heating are minimum, which is considered as an important factor in reducing problems of deposits.28 Huixian et al.34 suggested that there is no significant difference between ohmic heating and traditional method as whey protein is denatured at all temperatures. However, Pereira et al.62 found significant differences between ohmic heating and traditional method in their effects on whey protein denaturation. Ohmic heating is less denaturant due to absence of hot surfaces and volume heating of milk. Milk temperature has profound effect on proteins. Sensitivity of proteins to temperature varies. For example, casein proteins bear high temperatures higher than whey proteins which are affected by pasteurization temperature. However, casein proteins are affected by heat treatment at temperature higher than 100°C. The results showed that the protein percentage in pasteurized milk by ohmic heating 30 Novel Dairy Processing Technologies at 110 and 220 V was reduced from 3.6% in the raw milk to 3.5 and 3.54%, respectively (Table 1.1). This is because of changing some whey proteins at 27°C temperature and 5–10% of deposits, while deposits were 3.57 and 3.58% at 80 V and high traditional pasteurization, respectively. 1.9.2 MILK FATS Heat treatment does not have a pronounced effect on the milk fat percentage, but it affects the vitamins soluble in fats. In fact, effect of pasteurization temperature on milk fat is very low. Table 1.1 shows that milk fat percentage was reduced from 3.7% in the raw milk to 3.6 in pasteurized milk by ohmic heating at 220, 110, and 80 V, respectively, while it did not change in milk treated by high traditional pasteurization (3.7%) because of clustering of some fat globules in the holding tube.5 TABLE 1.1 Chemical composition Chemical Composition of Milk Treated by Ohmic Pasteurizer.5 Before High traditional pasteurization % pasteurization % Ohmic heating at 220 V 110 V 80 V Ash 0.68 0.71 0.73 0.69 0.69 Protein 3.6 3.57 3.5 3.54 3.58 Fat 3.7 3.7 3.6 3.6 3.6 Lactose 5.02 Moisture content 87 1.9.3 6.0 7.1 6.9 6.2 86.0 85.0 85.2 85.9 MILK LACTOSE It can be seen from Table 1.1 that lactose percentage after pasteurization was changed significantly. It was 5.02% before pasteurization and then was increased to 6, 6.9, 7.1, and 6% after pasteurization by using ohmic heating at 80, 110, 220 V, and high traditional pasteurization, respectively.5 1.9.4 MILK ASH Ash percentage in milk is affected with sterilization or pasteurization heat (Table 1.1). Ash percentage in raw milk was 0.68% then was increased to Technology of Ohmic Heating for the Pasteurization of Milk 31 0.73% in the pasteurized milk by ohmic heating at 220 V and it was 0.69% in pasteurized milk by ohmic heating both at 110 and 80 V. However, ash percentage in pasteurized milk by high traditional pasteurization method was 0.71% because the citrates were burnt; also CO2 and carbonates were evaporated during the incineration. 1.9.5 MOISTURE CONTENT OF MILK It can be seen in Table 1.1 that milk moisture content of raw milk was 87% compared to 85, 85.2, 85.9, and 86% in pasteurized milk at 220, 80, 110 V, and high traditional pasteurization, respectively. This is due to differences between raw milk temperature and temperature of pasteurized milk by ohmic heating. 1.10 EFFECTS OF OHMIC HEATING ON PHYSICAL PROPERTIES OF MILK 1.10.1 MILK ACIDITY The acidity of raw milk ranges from 0.14 to 0.18%. Milk acidity is due to the presence of milk proteins, CO2, and some acid salts, which are present in raw milk naturally. Table 1.2 illustrates that raw milk acidity is 0.15%, which is within the permitted range; however, the acidity was reduced to 0.14, 0.14, 0.13, and 0.14 % in pasteurized milk by ohmic heating at 220, 110, 80 V, and high traditional pasteurization, respectively, due to loss of soluble gases like CO2 lost and conversion of soluble calcium phosphate ratio into glutinous state.5 TABLE 1.2 Physiochemical Characteristics of Milk Treated by Milk Ohmic Pasteurizer.5 Physiochemical characteristic Before pasteurization High traditional pasteurization Total acidity 0.15 pH Alkaline phosphatase Ohmic heating 220 V 110 V 80 V 0.14 0.15 0.14 0.14 6.6 6.8 6.6 6.7 6.8 + − − − − 32 1.10.2 Novel Dairy Processing Technologies pH OF MILK pH is the negative logarithm of hydrogen ion in the media. Acid particles produce hydrogen ion. The pH is an inverse of the acidity because the source of acidity is lactic acid. The pH measurement refers to the concentration of hydrogen ions, which are produced from ionization of these compounds in acidic milk. The pH of raw milk is 6.6 and was reduced to 6.7, 6.8, 6.8, and 6.8 in pasteurized milk by ohmic heating at 220, 110, 80 V, and high traditional pasteurization, respectively. This increase in pH is due to decline in milk acidity. 1.11 DETECTION OF ACTIVITY OF ALKALINE PHOSPHATASE IN MILK Phosphatase is one of the important enzymes that must be tested to find pasteurization efficiency. Phosphatase is affected by pH and increase in temperature. The results showed that phosphatase is present (positive sign) in raw milk (Table 1.2), while it was absent in pasteurized milk for all treatments. FIGURE 1.16 (OH).5 Survival of alkaline phosphatase in milk treated by milk ohmic pasteurizer The required time for elimination of phosphatase was 5, 6.5, 7, and 7.5 min for pasteurized milk by ohmic heating at 220, 110, 80 V, and high traditional pasteurization, respectively. These results indicate that the Technology of Ohmic Heating for the Pasteurization of Milk 33 heating, electrical field and pressure (1.25–1.5 bar) using ohmic heating at 220, 110, and 80 V caused inactivation of alkaline phosphatase faster than high traditional pasteurization. Moreover, the survival alkaline phosphatase ratio in pasteurized milk was dropped to zero (Fig. 1.16). The survival alkaline phosphatase ratio is calculated from the following equation.50 Nj t dt log =−∫ o Dj N oj D j = Drj 10 Tri − T Z (1.67) (1.68) where Nj / Noj,t,Dj,Drj,Tri,T, and z are ratio of survival phosphatase, time (min), the decimal reduction time to lethal of 90% of phosphatase during one logarithmic cycle at specific temperature, the decimal reduction time to lethal of 90% of phosphatase during one logarithmic cycle at another temperature, pasteurization temperature, temperature, thermal resistance (°C), respectively; and Drj is calculated from the following equation:90 Dr j = (t2 − t1 ) l