Effects of hydroxyl radical on Listeria monocytogenes in fresh-cut iceberg lettuce (Lactuca sativa var. iceberg): Survival, membrane permeability, microstructure and virulence gene expression

Contamination of fresh-cut vegetables with Listeria monocytogenes is a food safety issue of particular concern. However, the inhibitory effect of hydroxyl radicals on Listeria monocytogenes in fresh-cut iceberg lettuce is not clear. This paper expounded the control effect and mechanism of hydroxyl radicals on Listeria monocytogenes in fresh-cut iceberg lettuce. Results showed that hydroxyl radicals (·OH) treated lettuce for 20 min could effectively inhibit the number of Listeria monocytogenes , and better maintain the sensory quality of fresh-cut lettuce. Hydroxyl radicals (·OH) increased cell membrane permeability and UV-absorbing substances by destroying the cell membrane integrity of Listeria monocytogenes ; and attenuated the virulence of Listeria monocytogenes by down-regulating the expression of the virulence-related genes actA and recA ; further affecting the survival and proliferation of Listeria monocytogenes in iceberg lettuce. This paper proposed an effective method to inhibit Listeria monocytogenes in fresh-cut lettuce, which will provide technical support and theoretical basis for its application in the fresh-cut lettuce industry. • Hydroxyl radicals can inhibit the growth of L. monocytogenes in iceberg lettuce. • Hydroxyl radicals disrupt cell integrity of L. monocytogenes in iceberg lettuce. • Hydroxyl radicals down-regulate the expression of virulence-related genes.