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Potential application of low dose gamma irradiation to improve the microbiological safety of fresh coriander leaves

Kamat, Anu, Pingulkar, Kiran, Bhushan, Brij, Gholap, Achyut, Thomas, Paul
Food control 2003 v.14 no.8 pp. 529-537
Listeria, Yersinia, carotenoids, chlorination, chlorophyll, cilantro, coliform bacteria, decontamination, fungi, gamma radiation, irradiation, leaves, markets, microbial load, microbiological quality, odor compounds, oils, pathogens, ready-to-eat foods, storage quality, surveys
A local market survey of fresh, raw coriander leaves, which is a component of many ready-to-eat, Indian dishes showed large variation in their bacterial load (7.0×106-1.36×108 cfu/gm) and mold and fungi (3.0×103-1.0×104 cfu/gm) and presence of potentially pathogenic bacteria such as faecal coliforms, Listeria and Yersinia. Conventional chlorination treatment affected the structural integrity of leaves leading to enhancement of rotting. Exposure to a low dose of 1 kGy was efficient for bacterial decontamination and elimination of potential pathogens without affecting the keeping quality of coriander leaves upto two weeks storage at 8-10 °C, measured visually in terms of degree of yellowing and rotting. Irradiation at higher doses led to the increased rotting during storage. The total chlorophyll contents as well its components, chlorophyll a and b did not change significantly on irradiation and subsequent storage. Similarly, the total carotenoid levels remained unaffected by exposure to 1 kGy dose, however, a dose dependent enhancement in their extractability was observed in irradiated leaves. No qualitative differences were observed in the GLC profile of volatile oils of control and irradiated (1 kGy) samples. There were no significant quantitative changes in the constituents of the major aroma compounds obtained from these two samples. Effects of irradiation on storage of the seasoning were also assessed.