[ effect of ascorbic acid combined with whey protein coating on the shelf-life of rainbow trout stored at refrigerator temperature: microbial and chemical analyzes]

ABSTRACT

Microbial growth, as a major source for meat and meat product spoilage, results in undesirable changes and thus leads to food poisoning, human mortality and also considerable economic losses. The aim of the present study was to inhibit the rainbow trout fillets bacteria during refrigeration by using whey protein coating containing Vitamin C. Rainbow trout fillets were kept in refrigerator for 16 days, considering 5 treatments, including control [C], coated with whey protein without Vit C [W], W treatment containing 0.5% vit C [W-AA1], W treatment containing 1% Vit C [W-AA2] and W treatment containing 1.5% Vit C. Microbial analysis including total viable counts, psychrophilic bactoria counts, lactic acid bacteria and Enterobacteriaceaeas as well as total volatile basic-nitrogen [TVB-N] and pH measuring were periodically performed every four days. Findings show that whey protein coating containing Vitamin C significantly reduced the total viable counts as well as psycrotrophic bacteria counts [P<0.05]. The number of lactic acid bacteria and enterobacteriaceas in coated treatment containing Vitamin C was lower compared to those of control treatment [P>0.05]. The use of this coating combined with Vitamin C also led to a reduction of TVB-N and pH values during storage [P< 0.05]. The result showed an antibacterial activity of whey protein edible coating containing Vitamin C which could extend the shelf-life of fillets for 4 days. In general, no significant difference was observed among the different treatment options containing Vitamin C