Effect of minimal processing operations on the quality of garlic,green onion,soybean sprouts and watercress

The effect of unit operational procedures on the quality of minimally processed vegetables was investigated. Peeling methods were studied for garlic, while different preparation forms were tried for garlic, green onion and soybean sprouts. Washing and a mild heat treatment, at 60°C for 30 s, were investigated as measures to reduce microbial populations of minimally processed vegetables. With garlic it was found that dry peeling was better than wet peeling in reducing microbial populations and preserving ascorbic acid content. Removal of the root, a potential source for microbial contamination, reduced microbial load in garlic. For garlic and green onion, microbial quality deteriorated with severity of cutting. Washing reduced microbial counts of prepared vegetables. Repeated washing and use of chilled water further reduced the counts. A mild heat treat-ment markedly reduced microbial counts in soybean sprouts and watercress, which were highly loaded with microorganisms. Sensitivities of vegetables to heat treatment differ and may limit the usefulness of heat treatment for some products. © 1998 SCI.