Study on the Effects of Gelatin Films Containing Lactobacillus hamnosus and Lactobacillus acidophilus Probiotics on the Survival of Staphylococcus aureus and Physicochemical Characteristics of the Carp Fillets at Refrigerator Temperature

Increasing the storage time and food safety has always been one of the most important concerns of food industry studyers. The aim of the present study was to prepare a gelatin film containing Lactobacillus rhamnus and Lactobacillus acidophilus probiotics and investigate its effects on Cyprinus carpio fillets by improving its physicochemical factors during storage at refrigerator temperature for nine days.

Treatments included control samples, film, film containing Lactobacillus rhamnosus, film containing Lactobacillus acidophilus and film containing a combination of two probiotic bacteria. Then, samples were packed in sterile polyethylene bags under laboratory conditions and stored at refrigerator temperature for nine days and every three days were assessed. On the assessment days, viability of the probiotics, count of Staphylococcus aureus, pH, quantities of volatile nitrogen bases (TVB-N), peroxide value (PV) and thiobarbituric acid (TBARS) were assessed.

Results showed that the survival rates of Lactobacillus acidophilus bacteria in gelatin film treatment and gelatin film treatment containing Lactobacillus acidophilus and Lactobacillus ramensus on the last day were 7.88 and 6.71 log cfu/g, respectively. Viability of Lactobacillus rhamnosus decreased in the treatments by 7.03 and 6.01 log cfu/g, respectively. Films containing probiotics better controlled the growth of Staphylococcus aureus in carp fillets, compared to the control group and the film group without probiotics. Based on the results, chemical assays included increasing trends and their changes in carp fillets treated with films containing probiotics were significantly lower than those in the control group and the film group without probiotics (p < 0.05).

Results of this study showed that the gelatin film containing probiotics included good antimicrobial characteristics against Staphylococcus aureus and could be effective in controlling the growth of pathogens and maintaining the sensory characteristics of fish and food products.