Application of ultrasound and chemical sanitizers to watercress, parsley and strawberry: Microbiological and physicochemical quality

This study aimed to evaluate the effectiveness of the use of ultrasound combined with chemical sanitizers for the decontamination of watercress, parsley and strawberries. Samples were treated with ultrasound (45 kHz) for 10 min in the presence of 20 and 200 mg/L sodium dichloroisocyanurate, 5% hydrogen peroxide, 10 mg/L chlorine dioxide or 40 mg/L peracetic acid. The treatment effects on physicochemical parameters and natural contaminant microbiota were evaluated. Sanitizing watercress with different treatments, such as hydrogen peroxide, chlorine dioxide, ultrasound in association with sodium dichloroisocyanurate, peracetic acid and chlorine dioxide, caused it to blacken. Sanitization caused watercress and parsley to darken, particularly the use of ultrasound in association with peracetic acid. All treatments with ultrasound promoted a reduction in strawberry firmness. All evaluated treatments of watercress, parsley and strawberries reduced aerobic mesophiles from 0.9 to 6.5 log CFU/g, 0.9 to 63 log CFU/g, and 0.7 to 4.0 log cycles, respectively. The combined treatment with ultrasound and 40 mg/L peracetic acid resulted in the highest reduction in the natural contaminant population. This finding indicates that ultrasound treatment can be an alternative to the vegetable sanitization step; however, more research is necessary to determine the best conditions for application of the proposed treatments. (C) 2015 Elsevier Ltd. All rights reserved.