Purpose: Evaluation of the antimicrobial properties of natural products accepted as food additives found in vegetables as isothiocyanates (ITCs) and in crustacean shells as chitosan (CHS), and their potential application in wash waters of fresh-cut produce to prevent cross contamination.
Methods: Antimicrobial properties of allyl ITC (AITC) and benzyl ITC (BITC) (5; 50; 100 µg/mL), and CHS (0.01; 0.1; 0.5; 1.0 %) against Salmonella were evaluated by standard plate count and impedance technique. The washing process of 25 g of fresh-cut iceberg lettuce in 1 L of tap water with CHS (0.1 %) or BITC (75 µg/mL) took place for 5 min, and was repeated twice within 2 subsequent days with reused water. Bacterial concentration was quantified in water and in the produce before and after the washing treatment.
Results: Increasing the concentration of CHS and BITC leads to a decrease in viable Salmonella of up to 2 and 3 logs, respectively. After the first washing cycle, 102 CFU/mL of natural bacteria present in lettuce is transferred to the water. The initial addition of BITC leads to a complete removal of bacteria in the wash water after 24 h, before starting the second cycle. CHS does not affect the viability of natural bacteria, but diminishes Salmonella concentration in water up to 2 logs after the 2ndcycle of washing.
Significance: BITC and CHS displayed a potential antibacterial activity against total coliforms and Salmonella, respectively, being able to effectively reduce and even completely inactivate bacteria during washing of fresh-cut produce, reducing cross-contamination and risk of outbreaks.