Optimization of allyl isothiocyanate sanitizing concentration for inactivation of Salmonella Typhimurium on lettuce based on its phenotypic and metabolome changes

Abstract

Allyl isothiocyanate (AITC), a natural compound, is a promising food additive and preservative because of its safety and effectiveness. In order to determine optimal AITC concentrations for disinfection of food pathogen on lettuce without compromising postharvest quality, various concentrations of AITC (0, 1, 2.5, 5 and 7.5 µL L^-1) were applied to Salmonella Typhimurium inoculated lettuce in air-tight box at 7 °C. As a result, the decline in visual quality, weight loss via cell membrane damage, and significantly reduced antioxidant activity were observed in lettuce treated with an AITC concentration of 2.5 µL L^-1, 5 µL L^-1 or higher. Moreover, metabolome analysis showed pattern of increased respiratory and cell damage, such as lipid peroxidation. Based on physiological changes, 1 µL L^-1 was determined as the optimal AITC concentration that significantly reduced S. Typhimurium population (4.01 log CFU g^-1) on lettuce.

Keywords: Allyl isothiocyanate; Postharvest quality; S. Typhimurium; Storage.