Purpose: The purpose of this study was to evaluate different combinations of LAB strains to inhibit L. monocytogenes on fresh strawberries.
Methods: Approximately three pounds of fresh strawberries were inoculated with a cocktail of L. monocytogenes strains (Scott A and Brie) at less than 4.00 log CFU/g. A portion of strawberries (25%) were reserved as an inoculated control (not treated) and the remaining strawberries were divided into the following LAB treatments, each applied as a dipping: 1) Lactococcus lactis FS56, 2) Lactobacillus acidophilus NP51 and Lactobacillus plantarum C28, and 3) L. lactis FS56, L. acidophilus NP51, and L. plantarum C28. After treatment, the strawberries were stored at 4°C with samples collected on days 0, 1, 3, and 7 to enumerate L. monocytogenes by plating on Modified Oxford agar. Microbial counts were log transformed. A repeated measures ANOVA was used to analyze the results.
Results: There was a significant treatment effect (P = 0.005) and the strawberries treated with 1) L. lactis FS56, 2) L. acidophilus NP51 and L. plantarum C28, and 3) L. lactis FS56, L. acidophilus NP51, and L. plantarum C28 all had a significant lower L. monocytogenes populations when compared to the control group.
Significance: These data suggest that the LAB treatments can serve as an effective intervention to reduce L. monocytogenes on fresh strawberries and will improve the safety of the product.