Optimization of aqueous ozone as disinfection treatment of Escherichia coli O157:H7 and the shelf life of hydroponic and organic butter head lettuce
Siti Fairuz, Y., Mahmud T.M.M., Ahmad S. H, Harizul, A., Farinazleen, M.G
Abstracts of 7th International Postharvest Symposium 2012 (IPS2012). 25-29 June, 2012. Putra World Trade Centre (PWTC), Kuala Lumpur, Malaysia. 238 pages.
2012
บทคัดย่อ
Escherichia coli O157:H7 is a gram negative bacterium and can cause a bloody diarrhoea due to toxins secreted when it infects human intestinal tracts. The effectiveness ofozonation on Escherichia coli O157:H7 was evaluated for the improvement in produce shelf life and food safety. The effects of aqueous ozone on hydroponic and organic butterhead lettuces were evaluated by varying the aqueous ozone concentrations applied as a potential food sanitizer especially for lettuce which is normally consumed raw. The produce quality was assessed by comparing the changes in texture or firmness, colour, chlorophyll content and vitamin C after treatment with aqueous ozone at 0, 3 and 5 mLL-1 and stored at 5°Cfor 12 days. The analysis was conducted on day 0, 4, 8 and 12 days of storage. The number of E. coli O157:H7 in organic lettuce was found to be higher than hydroponic lettuce. The aqueous ozone treatments were effective in reducing the E. coliO157:H7 contamination on the day of treatment applied but the effectiveness decreased as the storage period progressed. The aqueous ozone at 5 mLL-1 treatment resulted in the highest reduction of E. coli O157:H7 but the quality characteristics were negatively affected. The aqueous ozone at 5 mLL-1 was found to be the potential concentration for reducing E. coli O157:H7 without compromising the quality.