The effect of gelatin protein coat with clove extract for increasing the shelf life of chilled rainbow trout fillets at 4ºC

In this study, the effect of gelatin coating and clove extract for increasing the shelf life of chilled rainbow trout fillets was examined at refrigerator temperature. Samples were prepared on the basis of three treatments: control (without any coating), coating with 2% clove extract and coating with 4% gelatin plus 2% clove extract, then were kept in the refrigerator. Chemical analyses (containing: free fatty acids, pH, total volatile bases and thiobarbituric acid), microbial (containing: total viable, psychrophilic bacteria and enterobacter bacteria counts) and sensory analyses periodically were studied. Results showed that in the control treatment, the counts of total viable, psychrophilic bacteria and enterobacter bacteria were significantly higher than other treatments (P<0.05). According to the total microbial count at the end of the storage period (12th day), the sample of coating 4% gelatin plus 2% clove extract were allowed for eating, but the control sample was not allowed. Treated gelatin and clove extract was a good barrier to change pH. Amount of free fatty acids in treated samples in comparison with control were increased less and the data was significant since third day (P<0.05). In all samples, TBA and TVB-N were increased, but increasing in treated samples was slower. Sensory characteristics in the samples containing gelatin and using gelatin coat with clove extract is able to maintain quality and improve the shelf life of rainbow trout fillets during storage time at refrigerator temperature.