Comparison of two strategies enhancing the antagonistic effect of lactic acid bacteria in edible coating against Listeria monocytogenes on fresh-cut apple slices
Chun Hong Wong, Dan Li
Abstract
Listeria monocytogenes is a psychrotrophic pathogen and could be associated with ready-to-eat fresh-cut fruits stored at chilled temperatures. This study explored two different strategies in enhancing the antagonistic effect of lactic acid bacteria (LAB) against L. monocytogenes on fresh-cut apple slices. First, it was shown that pre-fermentation of a probiotic LAB, Lactiplantibacillus plantarum 299v with glucose and yeast extract exhibited remarkable enhancement in L. monocytogenes inhibition on fresh-cut apples. Second, psychrophilic LAB (pLAB) which are metabolically active at low temperatures were screened and one isolate named I29, identified as Leuconostoc gelidum subsp. gelidum, showed remarkable anti-Listeria effect. As a comparison, a pre-fermentation of L. plantarum 299v (LAB counts 7.7 ± 0.1 log CFU/g) with glucose (2% w/v) and yeast extract (0.06% w/v) showed equivalent inhibition effect on L. monocytogenes (a cocktail of SSA151, LM24, LM44, and BAA-839) with L. gelidum I29 cells (pLAB counts 6.7 ± 0.1 log CFU/g). In conclusion, both strategies were potential in inhibiting L. monocytogenes on fresh-cut apple slices, with respective advantages of accomplishing additional health beneficial effect from using the probiotic L. plantarum 299v and being economical and less laborious from using L. gelidum I29.