Preservative effect of food-based fermentate from Lactobacillus acidophilus NX2-6 on chilled pork patties.

The food-based fermentate (FBF) from Lactobacillus acidophilus NX2-6 has a broad-spectrum antibacterial activity but has not previously been reported as a food preservative. Experiments were conducted to assess its application as a preservative in pork patties. The effect of freeze-dried FBF on the microbiological parameters, physicochemical changes, and sensory evaluations of chilled pork patties stored for 15 days at 4°C was investigated. The five treatments evaluated included a control (meat only), nisin (meat plus 0.5% nisin), L.1 (meat plus 2% freeze-dried FBF), L.2 (meat plus 4% freeze-dried FBF), and L.3 (meat plus 8% freeze-dried FBF). The results showed that freeze-dried FBF could significantly (P < 0.05) inhibit aerobic bacteria, coliforms, Pseudomonas spp., and lactic acid bacteria, with the lowest microbial counts observed in L.3. The addition of freeze-dried FBF resulted in concentration-dependent decreases in total volatile basic nitrogen values and pH values but increases in lipid oxidation and color instability. Based on the criteria regarding microbiological and physicochemical parameters, the shelf life was 9 to 12 days for L.1, 12 to 15 days for L.2, and over 15 days for L.3, while the shelf-lives of the control and nisin treatments were 3 to 6 days, indicating that freeze-dried FBF could extend the shelf life by more than 3 days. Although the shelf life of L.1 was shorter than those of L.2 and L.3, the appearance of L.1 was much better than those of L.2 and L.3. Overall, treatment with 4 or 8% freeze-dried FBF could be improved if color and lipid oxidation could be improved by appropriate stabilizers, and a lower concentration (2%) of freeze-dried FBF has great potential as a natural and safe preservative in chilled pork patties.