SCREENING OF ESCHERICHIA COLI O157:H7 FROM HYDROPONIC AND ORGANIC 'BUTTERHEAD' LETTUCE AFTER AQUEOUS OZONE TREATMENT AND ITS EFFECT ON POSTHARVEST QUALITY

Y. Siti Fairuz, T.M.M. Mahmud, S.H. Ahmad, A. Harizul, M.G. Farinazleen
Escherichia coli O157:H7 is a gram negative bacterium and can cause a bloody diarrhea due to toxins secreted when it infects human intestinal tracts. The effectiveness of aqueous ozone on E. coli O157:H7 was studied for improvement in produce shelf life and food safety. Hydroponic ‘Butterhead’ lettuce were grown under a rain shelter and organic lettuce were grown in an organic-field plot at Taman Pertanian Universiti (TPU), UPM. After 41 days after transplant, both of the hydroponic and organic lettuce heads were harvested and immediately transported to the Postharvest Laboratory, UPM for analysis. The effects of ozone on hydroponic and organic ‘Butterhead’ lettuce were evaluated by varying 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 weight loss, firmness and chlorophyll content after treatment with aqueous ozone at 0, 3 and 5 mg L-1 and stored at 10°C for 12 days. The analysis was conducted on day 0, 4, 8 and 12 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. coli O157:H7 contamination on the day of treatment applied but the effectiveness decreased as the storage period progressed. The aqueous ozone at 5 mg L-1 treatment resulted in the highest reduction of E. coli O157:H7 but the quality characteristics were negatively affected. The aqueous ozone at 3 mg L-1 was found to be the potential concentration in reducing E. coli O157:H7 without compromising the quality.
Siti Fairuz, Y., Mahmud, T.M.M., Ahmad, S.H., Harizul, A. and Farinazleen, M.G. (2013). SCREENING OF ESCHERICHIA COLI O157:H7 FROM HYDROPONIC AND ORGANIC 'BUTTERHEAD' LETTUCE AFTER AQUEOUS OZONE TREATMENT AND ITS EFFECT ON POSTHARVEST QUALITY. Acta Hortic. 1012, 745-753
DOI: 10.17660/ActaHortic.2013.1012.100
https://doi.org/10.17660/ActaHortic.2013.1012.100
aqueous ozone, Escherichia coli O157:H7, disinfection, quality, food safety
English
1012_100
745-753

Acta Horticulturae