The effect of gelatin coating containing aqueous extract of Citrus sinensis peel on increasing shelf life of rainbow trout fillet during refrigeration

Today, the use of active packaging containing natural antimicrobial compounds such as essential oils and plant extracts has increased to increase the shelf-life of food  products. The purpose of this study is to investigate the effect of gelatin coating containing Citrus sinensis peel extract on increasing the shelf life of rainbow trout meat. Gelatin (4%) coating was prepared with different levels of Citrus sinensis peel extract (2% and 4%). After preparing the pieces of rainbow trout meat, all the pieces were coated and examined for chemical properties (pH, TVB-N, TBARS), microbial (TVCs and TPCs) and sensory properties (odor, color, texture and overall acceptance) were evaluated for 16 days at 4°C with a 4-day interval (0, 4, 8, 12, 16). The results of the investigation of the antimicrobial effect showed that in the samples coated with 2% and 4% levels of Citrus sinensis peel extract, the average count of mentioned bacteria was significantly lower than the control and gelatin alone (p < 0.05). The results of examining the chemical properties of the samples showed that pH, TVB-N and TBARS increased during the period, but this increase occurred at a slower rate in the samples coated with different levels of Citrus sinensis peel extract. In the evaluation of sensory characteristics, at the beginning of the study, all the samples had the highest acceptance limit, and with the passage of time and the appearance of signs of spoil, the scores decreased, especially in the control. Generally, the results showed that gelatin coating along with different levels of Citrus sinensis peel extract has a positive effect on increasing the shelf life of fish meat and these compounds can be used together to increase the shelf life of protein foods.