Abstract

In recent years, an increased demand worldwide for minimally processed products, especially leafy green salads, has been linked to an increased number of outbreaks of human gastroenteritis caused by associated food-borne pathogens, including Escherichia coli. In this study, treatment with ozone of simulated contaminations with E. coli (6–7 log CFU·g-1) on the baby leaves red chard at harvest and in the water used for washing were evaluated. Leaves (inoculated directly on leaves or inoculated in wash water) were washed by immersion in water with various doses of ozone (0 mg·l-1, 0.5 mg·l-1 and 1.0 mg·l-1) for 3 min. Then they were packed and stored at 5 °C for 12 days. On each day of evaluation, E. coli counts as well as leaf colour, respiration rate, chlorophyll, total phenolics content and antioxidant capacity were evaluated. The results indicated that simulated E. coli contamination on postharvest leaves was more difficult to reduce by ozonated water than contamination that occurred during the washing phase. Baby leaves red chard washed in ozonated water kept the quality parameters such as leaf colour, total phenolics content and antioxidant capacity during storage at 5 °C for 12 days.