Investigating the effect of polylactic acid-nanocellulose composite film along with Lactobacillus caseion the quality and shelf life of beluga sturgeon (Huso huso) fillet

Polylactic acid (PLA) nanocellulose (NC) composite film and probiotic bacteria Lactobacillus caseiwere used to increase the shelf life of beluga fillet at refrigerator temperature (4 ± 1 °C). First, the physical and mechanical properties of the films (1: PLA, 2: PLA-NC, 3: PLA-NC + L. casei) were investigated. Then the packed fillets (with the mentioned films) and control (without film) were evaluated in terms of chemical (PV, TBA, TVB-N, and pH), microbial (TVC, lactic acid bacteria, and Enterobacteriaceae) and sensory properties on days 0, 4, 8, 12 and 16. According to the results, the addition of L.casei improved the physical properties of the film, but it harmed the opacity and mechanical properties. With the increase of storage time in the refrigerator, the viability of L. caseiin the film decreased and its values were equal to 6.12 log CFU/g (at the end of storage time), however, it was within the permissible range (6 log CFU/g). Furthermore, the chemical, microbial, and sensory properties in the packed fillets were significantly lower than the control (P < 0.05). The best results were observed in PLA-NC + L. casei(P < 0.05), according to the suggested acceptable limit for these properties, this treatment was able to be maintained until the end of the storage period. All in all, the use of PLA-NC + L.caseihad a positive effect on improving the quality of beluga fillets during refrigerated storage, and it can be a suitable method for the production of probiotic films.