การลดความปนเปื้อนของจุลินทรีย์ในผักกาดหอมอินทรีย์ (Lactura sativa L.) โดยการล้างด้วยไมโครบับเบิลโอโซน

Abstract

Nowadays, organic lettuce is popular since consumers are healthy, but they face microbial contamination that causes various diseases when consumed with fresh crops. A Survey of microbiological quality of organic lettuce fresh products was investigated with 16 samples from 4 organic markets (Aggie Hut, Jingjai market, Royal Project outlet market, and Rimping supermarket) at Chiang Mai city. The microbial contamination of samples from Aggie Hut in the CMU market has the highest level of total coliform bacteria (1.84 x 104 cfu/g), followed by Jingjai market, Royal Project outlet market, and Rimping supermarket ranging from 1.17-1.43 x 104 cfu/g. A study of microbubble ozone washing to reduce microbial contamination in organic lettuce was determined. Microbubble ozone generator operated until the solution reached final oxidation-reduction potential (ORP) at 660mV. Then washing lettuce in a microbubble ozone bath with different temperatures at 15 and 25 °C and immersion times of 15 and 30 min were studied. The results showed washing lettuce at 15 °C for 30 min was the most effective in decreasing microbial contamination, reducing the amount of total coliform bacteria, Escherichia coli and yeast and mold by 68.32 %, 67.02% and 53.38%, respectively. Whereas Salmonella spp. was not detected. In addition, washing lettuce with microbubble ozone at a water temperature of 15 °C for 30 min then storing at 14 °C for 15 days and sampling every 3 days to measure the postharvest qualities. It was found that organic lettuce washing with microbubble ozone water did not show any significant differences in quality, including weight loss, chlorophyll content, leaf color change, customer acceptance as compared to unwashed and washed by tap water