{'fraction_non_alphanumeric': 0.04040895813047712, 'fraction_numerical': 0.013631937682570594, 'mean_word_length': 5.246200607902735, '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': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Effects of Chitosan Oligosaccharide–Nisin Conjugates Formed by Maillard reaction on the preservation of
 Collichthys niveatus

This study evaluated the effects of chitosan oligosaccharides (COS)–nisin conjugates (COS‐N CON) on the quality changes of Collichthys niveatus during storage at 4°C. COS–N CON were prepared by heating the aqueous solution of COS and nisin together at 80°C for 24 hr. In order to control the degree of conjugation, the total concentration and pH of mixed solution were adjusted to 2% and 2.00, respectively. COS–N CON were identified by Fourier transform infrared (FT–IR) and X–ray diffraction analysis (XRD). During storage, COS–N CON treated samples showed retarded sensory and texture deterioration, with significantly slower increase rate of pH, total viable counts (TVC), and total volatile basic nitrogen (TVB–N). At the day 6, the TVC, TVB–N, and hardness of C. niveatus treated with distilled water reached 6 log₁₀(CFU/g), 28 mg/100 g, and 15 g, respectively; while that in COS–N CON treated samples was 5.1 log₁₀(CFU/g), 21 mg/100 g, and 18 g, respectively. Based on indicating parameters tested, it was revealed that the COS–N CON treatment could prolong the shelf life of C. niveatus by 2 days during chilled storage, compared to the chitosan oligosaccharides (COS)–nisin mixture (COS–N MIX). PRACTICAL APPLICATIONS: The novel preservation agent we created in this study could be considered as safe and renewable, which could be a great advantage in practical application. It was formed by conjugating chitosan oligosaccharides (COS) with nisin via Maillard reaction. Both COS and nisin were considered as green and renewable antimicrobial agents. Maillard reaction is one of the main reactions taking place in food that does not need catalyst and organic solvent. COS–nisin conjugates had a better effect on preservation of Collichthys niveatus, compared with COS–nisin mixtures, which indicating Maillard reaction could be the effective way in modifying the preservation properties of natural antimicrobial agents.