Combined effects of thermosonication and slightly acidic electrolyzed water on the microbial quality and shelf life extension of fresh-cut kale during refrigeration storage

Ahmad Rois Mansur, Deog-Hwan Oh

Department of Food Science and Biotechnology, School of Bioconvergence Science and Technology, Kangwon National University, Chuncheon, Gangwon 200-701, Republic of Korea.

Abstract

This study evaluated the efficacy of thermosonication combined with slightly acidic electrolyzed water (SAcEW) on the shelf life extension of fresh-cut kale during storage at 4 and 7°C. Each kale (10 ± 0.2 g) was inoculated to contain approximately 6 log CFU/g ofListeria monocytogenes. Each inoculated or uninoculated samples was dip treated at 40°C for 3 min with deionized water, thermosonication (400 W/L), SAcEW (5 mg/L), sodium chlorite (SC; 100 mg/L), sodium hypochlorite (SH; 100 mg/L), and thermosonication combined with SAcEW, SC, and SH (TS + SAcEW, TS + SC, and TS + SH, respectively). Growths of L. monocytogenes and spoilage microorganisms and changes in sensory (overall visual quality, browning, and off-odour) were evaluated. The results show that lag time and specific growth rate of each microorganism were not significantly (P > 0.05) affected by treatment and storage temperature. Exceeding the unacceptable counts of spoilage microorganisms did not always result in adverse effects on sensory attributes. This study suggests that TS + SAcEW was the most effective method to prolong the shelf life of kale with an extension of around 4 and 6 days at 4 and 7°C, respectively, and seems to be a promising method for the shelf life extension of fresh produce.

Keywords: Fresh-cut kale; Thermosonication; Slightly acidic electrolyzed water; Microbial quality; Sensory shelf life.