EFFECT OF POLYLYSINE AND CARRAGEENAN COATING ON MICROBIAL PROPERTIES OF RAINBOW TROUT (ONCHORYNCHUS MYKYSS) DURING CHILLED STORAGE AT 4˚C

Background and Aim:Extending the shelf life of foods and delaying their spoilage is one of the most important goals in the food industry. The use of coatings and natural, non-chemical and safe preservatives is one of the useful ways to increase the shelf life of food.Methods:This study was conducted to investigate the effects of ε-polylysine, carrageenan coating and ε-polylysine + carrageenan coating on microbial properties of rainbow trout stored at 4 ± 1℃ for a period of 15 days. All samples were subjected to microbial analysis on the day of treatment and periodically every 3 days until 15 days.Results:Throughout the storage period, the number of bacteria in the control group was higher than the treatment groups and the lowest microbial count was observed in ε-polylysine + carrageenan coated group. At the end of the storage period in control group, the number of enterobacteriaceae, lactic acid, mesophilic and psychrophilic bacteria increased to 9.03, 6.77, 10.95, 11.17; whereas in ε-polylysine + carrageenan coated group reached to 5.22, 4.55, 7.48, 10.06 log CFU/g, respectively.Conclusion:In this study, ε-polylysine could effectively prevent the growth and proliferation of bacterial population and showed good potential as a food-grade, novel, safe and effective natural food additive and carrageenan coating also showed good ability to prevent growth of aerobic bacteria. The results of this study showed that the use of ε-polylysine + carrageenan coating was more effective on delaying microbial growth than other treatment. Consequently increased shelf life of trout fillets during 15 days of storage.

Keywords:

ε-polylysine , carrageenan , coating , microbial properties , rainbow trout , chilled storage