{'fraction_non_alphanumeric': 0.04951185495118549, 'fraction_numerical': 0.03912908724624206, 'mean_word_length': 4.827088036117382, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 11, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Interactions of vegetable proteins with other polymers: Structure-function relationships and applications in the food industry

Abstract Background In recent years, there has been increasing interest in vegetable proteins, due to their various health beneficial functions and wide applications in the food industry. Vegetable proteins combined with other edible polymers can be used to improve the quality and nutritional value of food products. In these complex food systems, interactions between different components are inevitable, and these interactions have a significant influence on the structure and functions of food products. Scope and approach This study reviews the current status of knowledge of interactions between vegetable proteins and other polymers (proteins or polysaccharides) in food systems and the structure of complexes formed by these interactions. The study also provides a comprehensive review of the applications of the complexes. Key findings and conclusions Vegetable proteins display different types of interactions with other polymers (e.g., polysaccharides, or animal proteins) under different conditions, thus forming a variety of complexes with different structures (e.g., double networks, mosaic textures and cross-linked structures), which showed different impact on properties of the final food products and their applications (e.g., substitution for fat, or encapsulation for bioactive ingredients) in the food industry. However, previous studies mainly focused on leguminous proteins and vegetable-protein-based mixtures of two polymers, further studies on other vegetable proteins and more complex food systems containing vegetable proteins and other polymers are required.

In addition, the location of the proteins inside plan seeds can influence the 89 extraction of proteins (Kasai & Ikehara, 2005). In order to improve protein 90 extractability, different extraction processes such as microwave heating (Choi,Choi,91 Chun, & Moon, 2006) and ultrasound technology (Karki, et al., 2010) were 92 investigated, which may cause the protein denaturation (Fukase, Ohdaira, Masuzawa, 93 & Ide, 1994;Hafez, Mohamed, Hewedy, & Singh, 1985). During the extraction of 94 proteins, many factors (e.g., the types of the solvent, the temperature and pH of the 95 reaction system, the agitation speed and extraction time) can be optimized to recover 96 proteins and prevent the loss of their solubility (Karaca, Low, & Nickerson, 2011;Wu, 97 Wang, Ma, & Ren, 2009). 98 Many strategies have been developed to prevent the denaturation of proteins 99 during food processing or storage, such as molecular modification of vegetable 100 proteins (Wang, Wang, & Sun, 2005) or mixing vegetable proteins with other 101 polymers (Liang, Wong, Pham, & Tan, 2016). In these multi-components food 102 systems, the interactions between vegetable proteins and other components will 103 inevitably take place in a variety of ways. These interactions can potentially have 104 great influences on the structures and properties of these food products (Zhao, Dong, M A N U S C R I P T A C C E P T E D Protein-protein interactions have been well investigated with the objectives of 135 clarifying structure-function relationships, improving food quality, and developing 136 new products (Sarbon, Badii, & Howell, 2015). Interactions of proteins at oil-water or 137 air-water interfaces can maintain the stability of emulsions or foams, respectively 138 while the interactions between protein molecules in proteins solutions are essential to 139 the formation of protein gels and films. Single food protein stabilized emulsions are always sensitive to temperature, salt 143 and pH (Mcclements, 2004). Compounded utilization of two types of proteins with 144 different structures as emulsifier is a simple and controllable way to improve the 145 stability of single protein stabilized emulsions (Liang, et al., 2016;Ventureira, et al., 146 2012). The study of Ji et al. (2015) can be used as a good example to clarify the 147 structures of mixed proteins at oil-water interfaces. Sodium caseinate (SC) and soy 148 protein isolate (SPI) were shown to bind to oil-water interfaces to form negatively 149 charged compact interface structures at pH6.8 (Fig. 2), while pH and ionic strength 150 were shown to affect the surface charge and the particle size of a SC-SPI-stabilized . In most cases, a mixture of two or more different proteins will lead to phase 160 separation, e.g., coagulation and segregation. When phase separation occurs, two or 161 more proteins form independent phase-separated networks, and they may disturb the 162 assembly of a uniform network structure (Chronakis & Kasapis, 1993;Sarbon, et al., 163 2015). A mixture of two oppositely charged proteins can result in aggregation induced 164 by electrostatic attraction (Sarbon, et al., 2015). as an example of low molecular weight proteins, whey protein could occupy the 187 interaction sites of collagen molecules, weakening the ordered structure of collagen 188 networks (a crater-shaped form) (Walkenström & Hermansson, 1995); however, blood 189 plasma proteins could form a uniform network structure with collagen (Oechsle,190 Häupler, Gibis, Kohlus, & Weiss, 2015   . 301 Properties of proteins and polysaccharides (e.g., charge density, molecular 302 weight and branched chain) and their concentrations or ratio have a big influence on 303 the protein-polysaccharide network structures (Ma, Dang, & Xu, 2016). 304 Polysaccharides can be classified as negatively-charged (e.g., xanthan gum (XG) and 305 pectin), naturally-charged (e.g., guar gum and galactomannans), and  . 317 Therefore, the environmental pH must be properly controlled to ensure that the 318 proteins and polysaccharides are oppositely charged, which is essential for the 319 formation of a stable protein-polysaccharide complex by electrostatic attraction 320 (Spada, Marczak, Tessaro, & Cardozo, 2015;Yuan, et al., 2014). In addition, salts 321 (e.g., sodium, potassium, calcium and magnesium chloride) can influence the    Zhu, et al., 2015;Wang, et al., 2014). Meanwhile, phase separation is 393 also conducive to improving water vapor, in a different manner from that in 394 protein-protein films (Sun, et al., 2013). Possibly because interwoven compact structures between proteins and polysaccharides have been formed, which inhibits the 396 penetration of water into matrixes (González & Alvarez Igarzabal, 2015).  products with novel textures (Chang, et al., 2014;Li, et al., 2007;Monteiro, et al., 434 2013). As shown in Table 3 (Gan, Latiff, et al., 2009;Guo, et al., 2014;Hou, et al., 2015). better heat stability than those stabilized by only proteins (Zhao, et al., 2015). In addition, vegetable proteins are commonly used as fillers or fat stabilizers to 514 improve the textures of meat products, such as surimi, pork meat gels and meat batters 515 (Luo, et al., 2008;Pietrasik, Jarmoluk, & Shand, 2007;Youssef & Barbut, 2011). 516 Meanwhile, in order to improve qualities of food products involving vegetable 517 proteins, it is becoming increasingly common to modify vegetable proteins by 518 different ways (e.g., by transglutaminase-catalyzed cross-linking, high pressure, 519 ultrasound, or microwave treatment) (Feng, et al., 2014;Guan, et al., 2011;He, et al., 520 2014;Jambrak, Lelas, Mason, Krešić, & Badanjak, 2009;Pietrasik, et al., 2007). 521 However, the addition of vegetable proteins has a great influence on the texture and 522 sensory quality of food; inclusion of large amounts of vegetable proteins may destroy 523 the textures of meat products and introduce undesirable flavors (Luo, et al., 2008). and high digestibility (Kręcisz, Wójtowicz, & Oniszczuk, 2015). However, extruded 529 food products always contain low levels of protein and fiber (Yu,Ramaswamy,& 530 Boye, 2013). Vegetable proteins can be used to improve the protein content and thus 531 nutritive value of extruded food products (Kasprzak, et al., 2013;Konstance, et al., 532 1998;Yu, et al., 2013). Vegetable proteins also have a great influence on the flavor of 533 extruded foods. Variety of interactions between different ingredients in foods (e.g., the 534 Maillard reaction) during extrusion processing can lead to production of various food 535 flavors (Solina, Johnson, & Whitfield, 2007 Paraskevopoulou, Chrysanthou, & Koutidou, 2012;Villarino, et al., 2015;Ziobro, et 552 al., 2013). 553 In general, vegetable proteins can reduce the density, hardness, chewiness and 554 springiness of breads due to their high viscosity and water-holding capability (Ziobro, 555 et al., 2013). High level of vegetable proteins may increase the hardness of final 556 products (Crockett, et al., 2011;Ziobro, et al., 2013).   systems. SPI formed a mixed interwoven structure with collagen (Oechsle, et al., 2015). wt%) can induce a partial dissociation of the protein's rigid structure with SPI. Stevioside at high concentration (2 wt%) can replace SPI-STE complexes due to their smaller particle size .

M A N U S C R I P T
A C C E P T E D ACCEPTED MANUSCRIPT Table 1 Summarize of interactions between vegetable proteins and other polymers.

Table 2
Selected examples of structures and properties of films formed by vegetable proteins and other polymers.

Table 3
Selected examples of structures and properties of gels formed by vegetable proteins and other polymers.

M A N U S C R I P T
A C C E P T E D ACCEPTED MANUSCRIPT Table 1 Summarize of interactions between vegetable proteins and other polymers.
(Chang, Li, Wang, Bi, & Adhikari, 2014;Lam, Shen, Paulsen, & Corredig, 2007;Ma, Dang, & Xu, 2016;Yuan, et al., 2014) Concentration or mixture ratio affects the competitive adsorption of two molecules at interfaces and the dispersity of polymers in solutions. (Chang, et al., 2014;Li, Yeh, & Fan, 2007; The pH value of reaction system affects the surface charge of proteins and thus protein-polysaccharide interactions. (Spada, Marczak, Tessaro, & Cardozo, 2015;Yuan, et al., 2014) Salts can shield charged-sites of both protein and polysaccharide molecules, and the means of adding salts can affect the reaction rate. (Li, et al., 2009;Pires Vilela, et al., 2011;Yuan, et al., 2014) M A N U S C R I P T M A N U S C R I P T

A C C E P T E D ACCEPTED MANUSCRIPT
A C C E P T E D ACCEPTED MANUSCRIPT Table 3 Selected examples of structures and properties of gels formed by vegetable proteins and other polymers.
Storage modulus (G') decreased as pea protein level increased. MTG increased G' and peak force values.
Water-holding capacity (WHC) increased as PPI level increased. Breast and thigh SSP showed the highest strength and springiness on addition of 2.5% and 3.5% PPI, respectively. PPI also could increase G' value of gels. Fracture strain and stress of the mixed gels were higher than that of gellan gum gels but lower than that of SPI gels; trend for Young's modulus was the opposite. The mixed gels were firmer with increasing gellan gum level (0-0.4%).
The apparent viscosity, and G' and G'' values of the mixed gels increased with the increase in the gum (XG, GG) concentration.
Mixed gels produced by pre-cross-linked SPI showed higher G' values than those produced by non-pre-cross-linked SPI. SPI-ribose gels showed lower G' values than SPI-sucrose gels.
The double network gel formed by SG-SBP with laccase had higher G' value and mechanical toughness (fracture strain and stress) than the single network gel formed by SG-SBP without laccase.

M A N U S C R I P T
A C C E P T E D ACCEPTED MANUSCRIPT Fig. 3. Influence of co-gelling proteins on the structures and storage modulus (G') of collagen matrices. Whey protein isolate and blood plasma proteins embedded in the surface of collagen, while whey protein isolate may interrupt the collagen interconnections and weaken the structure; blood plasma proteins could not increase G' value of collagen. Gluten led to phase separation in mixed systems. SPI formed a mixed interwoven structure with collagen (Oechsle et al., 2015).

M A N U S C R I P T
A C C E P T E D ACCEPTED MANUSCRIPT Fig. 4. Bulk and interfacial behaviors of soy protein isolate-stevioside (SPI-STE) mixtures with different stevioside concentrations at the oil/water interface. Stevioside at low concentration (0.1 wt%) can only bind to the gaps between protein molecules. Stevioside at intermediate concentration (0.25-1 wt%) can induce a partial dissociation of the protein's rigid structure with SPI. Stevioside at high concentration (2 wt%) can replace SPI-STE complexes due to their smaller particle size .

M A N U S C R I P T
A C C E P T E D ACCEPTED MANUSCRIPT • The structure-function relationship of vegetable proteins based biopolymers or materials is discussed.
• Understanding structures of complex food systems containing vegetable proteins has an important implication for applications of vegetable proteins.