Effect of Hot Water Treatment on Storage Quality of Minimally Processed Onion

摘要

Storage quality of minimally processed onion as influenced by hot-water dipping was investigated to examine feasibility of mild heat treatment as efficient post-processing method. Fresh onions were peeled, trimmed, and dipped in hot water at varioustemperatures (50-80°C) for 1 min. Heat-treated onions were cooled, de-watered, packaged in low density polyethylene (LDPE) film pouches (63 μm thickness), and stored at 10°C. Samples treated at higher temperatures (70-80°C) showed significant increases in flesh weight loss and discoloration during storage as compared to others. Hot-water dipping remarkably reduced initial microbial load of prepeeled onions, with over 1 log cycle decrease in aerobic bacterial count. After 7 days storage, no significant differences in viable aerobe count were observed among treated and untreated samples, with both showing 10~6-10~7 CFU/g. For sensory attributes including discoloration, wilting, decay, and visual quality, onions treated with hot-water dipping at 60°Cscored highest. Results suggested hot-water dipping at specific condition as practical postprocessing treatment could effectively prolong shelf life of minimally processed onion.