Chlorate uptake during washing is influenced by product type and cut piece size, as well as washing time and wash water content

During the processing of fresh produce, washing with chlorinated water may result in an unacceptable source of chlorate as a disinfection by-product (DBP) in the finished product. The differential ability for the uptake of chlorate by different fresh-cut products during washing was evaluated. Results showed that chlorate uptake was affected by the type of produce, with shredded carrots showing greater chlorate uptake than baby leaves or chopped lettuce which had intact epidermis. Among leafy vegetables, baby leaves showed greater chlorate uptake than chopped lettuce due to anatomical differences that promoted the uptake of chlorate via leaf surface. Baby leaves were characterized by a high leaf area/weight ratio, high stomatal density and intercellular spaces. Moreover, the chlorate uptake was greater when increasing the cut grade, being greater in shredded than in chopped or large cut lettuce as well as it was greater in shredded carrots than in discs or sticks. Results in baby leaves showed also that lower leaf water content and longer washing time increased chlorate uptake significantly. Chlorate uptake showed a linear response with the chlorate content present in the wash water, without a saturation effect for the tested concentrations and types of produce. In conclusion, the uptake of chlorate expressed in % with respect to the content in wash water was affected by the type of produce and cut piece size with a greater ability for the accumulation in shredded carrots followed by baby leaves and shredded lettuce.