Multifunctional bio-preservative potential of <i>Lactobacillus plantarum</i> postbiotics: thermal stability and efficacy in food models

Rising health concerns over synthetic food additives have boosted demand for natural alternatives. While probiotics are known to inhibit various common food spoilage bacteria, their metabolites and inactivated cells, collectively defined as postbiotics, offer superior stability and safety. This study assessed the effectiveness of postbiotics in food preservation, focusing on environmental stress tolerance, stability, and functional traits, specifically antioxidant and antibacterial capacities. Using Lactobacillus plantarum 299 V as a model, we analyzed the antibacterial activity and stability of its postbiotics under varying thermal and pH conditions, as well as in a simulated gastrointestinal environment. Additionally, we investigated the correlation between fermentation duration and antioxidant capacity. Results indicated that postbiotics retained significant antibacterial activity after high-temperature treatment (121°C, 30 minutes) and demonstrated notable stability under gastrointestinal conditions. Significantly, postbiotics displayed consistent enhancement in total antioxidant capacity over time under various storage temperatures. Antioxidant activity peaked at 16 h of fermentation, while antibacterial effects declined at pH levels above 5. Practically, they completely inhibited Staphylococcus aureus in milk. Moreover, when incorporated with the postbiotics, edible films incorporated with them showed potent antioxidant activity, effectively preserving bananas and pork. These postbiotics serve as stable, effective bio-preservatives, providing a natural, sustainable solution for food preservation.