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Supplying fresh fish and sea products is accompanied with the problem of their rapid spoilage and short shelf life. Therefore, solutions which help increase this shelf life have always been valued. Accordingly, the aim of this study was to evaluate the effect of whey protein coatings containing four different concentrations (100,200,400 and 800 IU/gr) of nisin in perch fillet for storage in refrigerator temperature. Humidity tests, Peroxide Value, Thiobarbituric acid Index, microbial load, water activity and pH were performed over coated and uncoated samples. The results indicated that increasing the shelf life in all treatments led to an increase in peroxide value, Thiobarbituric acid Index, the load of bacteria, pH and water activity, this increase was less in coated samples than the uncoated ones. On the other hand, the findings showed that whey protein and nisin coating with the of concentration 400 IU/gr of perch fillet can add 16 days to increase the shelf life in refrigerator temperature in comparison with the uncoated samples. Based on our findings, it can be concluded that using whey protein coating containing nisin with the concentration of 400 IU/gr of perch fillet as edible coating  can increase the shelf life in the refrigerator temperature.

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 In general, keeping beef fillets in the refrigerator (4 ° C) will be spoiled due to the growth of microbes, which endangers the food and economic health of the consumer. Therefore, the aim of this study was to investigate the effects of whey protein coating. And gelatin with three levels of whey protein (0, 0.5 and 1%), three levels of gelatin (0, 0.5 and 1%) and two concentrations of whey protein-gelatin combination (0.5 and 1%) In order to increase the shelf life of beef fillet at refrigerated temperature. For this purpose, tests of moisture, peroxide number, thiobarbituric acid index, microbial load and general acceptance were performed on coated and uncoated beef fillets. The results showed that with increasing storage time in all treatments, the amount of peroxide and thiobarbituric index of samples increased, which was less in coated samples than uncoated samples (p <0.05) and with increasing storage time, moisture content of fillets. Without coverage as well as overall acceptance of samples decreased significantly. The minimum amount of bacteria also belonged to the samples coated with 1% whey protein-gelatin. Based on the obtained results, it can be concluded that the use of whey protein and gelatin combination coating with a concentration of 1% as an edible coating in beef fillet was selected as the best treatment.