Technology for maintaining microbiological quality and safety of fresh-cut vegetables in Japan
Hidemi Izumi
Proceedings of the APEC symposium on postharvest handling systems Bangkok, Thailand September 1-3, 2003. p. 83
2003
บทคัดย่อ
Technology for maintaining microbiological quality and safety of fresh-cut vegetables in Japan
Microbiological characteristics on fresh-cut vegetables need to be focused not only on spoilage bacteria but also foodborne pathogenic bacteria. Thus we have been studying the efficacy of treatments with electrolyzed acidic water as a chemical disinfectant or hot water as a physical sterilization to reduce bacterial flora on fresh-cut vegetables. Electrolyzed acidic water (pH 2.7 or 6.5, 20-60 ppm available chlorine), generated by electrolysis of NaCl solution using electrolyzed water generator, was approved as food additives by Ministry of Health, Labor and Welfare of Japan in 2002. The bactericidal effect of electrolyzed acidic water containing 50 ppm available chlorine was similar to that of sodium hypochlorite solution containing 50-200 ppm chlorine with fresh-cut spinach and cucumber. L-Ascorbic acid and potassium contents were higher in fresh-cut spinach, cucumber, carrots and potatoes treated with electrolyzed acidic water than with sodium hypochlorite solution. These contents were the least on a few fresh-cut vegetables when treated with sodium hypochlorite solution containing 200 ppm chlorine. Electrolyzed acidic water did not affect surface color and sensory taste of fresh-cuts. Hot water treatment of 100 °C for 1 sec of trimmed cucumber during processing at a commercial produce plant contributed to a large reduction of total bacterial count to 2.4 log CFU g-l and coliform group to non-detectable level. The hot water treatment did not affect the visual quality of cucumber product. The number of genera found on final fresh-cut product was less than that on the initial raw product and was in proportion to microbial count on each product. The predominant isolates from fresh-cut cucumber were plant pathogenic bacteria such as Pseudomonas spp. and on human pathogens were detected. The micro flora of fresh-cut cucumber reflected the epiphytic microorganisms on raw cucumber and contamination during preparation of fresh-cut product.