Effect of biodegradable whey protein-lactoperoxidase system coating on shelf-life extension of shrimp during refrigerated storage

Abstract

Introduction: Growth and reproduction of bacteria, especially Gram-negative bacteria are considered as the most important seafood spoilage. The use of films and antimicrobial coatings is one of the ways to prevent corruption and increase the shelf-life of foods. Considering the potential of the antimicrobial activity of the lactoperoxidase system (LPOS), in the present study, the effect of this system with whey protein coating as one of the substances that can be used to produce films and edible coatings has been shown to increase the shelf life of fillets shrimp kept in the refrigerator (temperature 4 ±1 0C) were investigated. Material & methods: After preparing the whey protein coating solution, the activated lactoperoxidase preparation system was added at 0 (control), 1.25%, 2.5%, 5% and 7.5% levels. Then samples of shrimp fillet were covered with immersion method with the mentioned levels. The samples were then for 16 days in a refrigerator (temperature 0C1 ± 4) were kept during the microbial test (, mesophilic bacteria, Pseudomonas, psychotropic bacteria, Pseudomonas fluorescent bacteria Shewanella Pvtryfasyns), chemical test (total volatile basic nitrogen, Thiobarbituric Acid Test, Free Fatty Acid and Peroxide Index) and sensory evaluation were performed on days 0, 4, 8, 12 and 16. Results: According to the results, the presence of lactoperoxidase system with whey proteins has led to a lower number of bacteria in all levels than in the control group. At higher levels of lactoperoxidase system, the difference was significant between the number of bacteria and the control group. It also the use of the system with whey protein led to the formation of a total volatile nitrogen base is significantly lower than the control group. However, no significant effect was observed on the amount of free fatty acids and lipid oxidation assays (Thiobarbituric Acid Test and Peroxide Indicator). The results of the sensory evaluation also demonstrated the effectiveness of using the lactoperoxidase system in maintaining the quality and shelf life of shrimp fillets during storage in the refrigerator. In sensory evaluation and testing, as well as microbial tests and the measurement of the total volatile of basic nitrogen, with increasing concentrations of lactoperoxidase system, in the whey protein coating were better results in terms of proximity to acceptable limits for shrimp meat was observed. Conclusion: The combination of the LPOS with whey protein coating has been protected significantly against some bacterial growth and TVB-N formation, while it did not have significant effect on the rate of lipid oxidation compared with the control group at all sampling time. The results of sensory evaluation showed the effectiveness of the LPOS use in maintaining the quality and increasing the shelf life of shrimp fillets kept in the refrigerator.