Development of postbiotic-enriched chitosan films as a novel approach for sustainable food packaging

This study investigated the potential of postbiotics from fermented rice bran (RBPs), produced by newly isolated Lactiplantibacillus strains from bee gut, human breast milk, and camel milk, as a novel bioactive agent in the development of bioactive chitosan films for food preservation. Incorporating 10 % (v/v) RBPs into chitosan films significantly improved their mechanical and barrier properties, increasing tensile strength (from 3.74 to 9.61 MPa) and elongation at break (from 56.32 % to 88.61 %), while reducing water vapor permeability (from 19.88 to 9.38 g mm/m².h.kPa) and oxygen permeability (from 0.368 to 0.21 cc/m².24 h atm). The films also demonstrated enhanced antioxidant activity (up to 2.8-fold) and antioxidant capacity (up to 2.5-fold) compared to control films. When applied to salmon fillets for 12 days of cold storage, the RBP-chitosan films effectively preserved quality by significantly reducing lipid oxidation (2.30–3.75 mg MDA/kg compared to 12.8 mg MDA/kg in unwrapped samples) and protein degradation (14.25–19.85 mg/100 g compared to 34.65 mg/100g in unwrapped samples). Moreover, microbial growth was suppressed, maintaining total viable counts below the maximum acceptable level (log 7 CFU/g) for the full 12 days—compared to just 5 days for control films. Notably, films containing RBPs from Lactiplantibacillus strains (sourced from human breast milk and Lactiplantibacillus apis) exhibited the most effective antimicrobial activity, maintaining Escherichia coli counts within the safe limits (≤ log 2 CFU/g) for up to 9 and 11 days, respectively. These findings highlight RBP-chitosan films as a sustainable strategy for extending perishable food shelf life, leveraging RBPs to enhance film performance and preservation efficacy.