Experimental study of the effect of sodium caseinate-gelatin probiotic film containing Lactobacillus paracasei, Bifidobacterium bifidum, and Lactobacillus plantarum on the survival of Staphylococcus aureus on rainbow trout fillet

In recent years, increasing the shelf life and preventing the spoilage of highly perishable food products such as fish has become a significant challenge for scientists and professionals in the health industry. These products not only pose health risks to the general public due to the transmission of pathogens to consumers and the creation of health hazards, but they also have economic importance. Materials and Methods: This research aimed to prepare probiotic films from sodium caseinate-gelatin containing Lactobacillus paracasei, Bifidobacterium bifidum, and Lactobacillus plantarum, and to evaluate their application in the microbial and mechanical properties of salmon fillets during 12 days of refrigerated storage. The physical and mechanical properties of the designed films were assessed. Additionally, the salmon fillets were examined for microbial parameters. Results: Based on the findings, a negative correlation was observed between the survival of probiotic bacteria and the storage time of the films. The number of Lactobacillus paracasei, Bifidobacterium bifidum, and Lactobacillus plantarum bacteria started from day 0 with values of (2.9, 3.9, and 1.9 log cells) respectively, and reached (6.79, 5.84, and 6.14 log cells) by the end of the study (day 12). In other results, it was observed that sodium caseinate-gelatin probiotic films delayed microbial growth in salmon fillets compared to the control group. Conclusion: Overall, sodium caseinate-gelatin probiotic films significantly increased the shelf life of salmon fillets and can be considered as innovative packaging materials with potential applications in various industries, especially the food industry.