Shanker , Adarsh and Kumar , Vipin and Tewary, D K (2003) Fate of pesticide residues on tea from leaf to cup (2003). International Journal of Tea Science, 2 (4). pp. 18-26.

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This comprehensive review of the fate of pesticides deposited on tea leaves focuses on the wide variations in MRL levels fixed by different agencies viz., EU, EPA, Codex, which may differ by as much as 200 times in individual chemicals. Hence, there is a need for harmonization of pesticide residue limits, which should be agreed to by all the stakeholders. The main factors that determine the pesticide load are the characteristics of chemicals; prevailing field conditions; the process of manufacturing and finally preparing tea infusion, including the brewing time and temperature. Lipophyllic compounds get attached to the waxy layer in leaf cuticle while systemic pesticides are translocated to other plant-parts afferabsorption. Both of them protect the chemical from exposure to degradative processes. The half-life of most of the pesticides varies widely but is generally less than two days. Further, the pesticides on leaf surface are degraded by growth dilution, photolysis by sunlight, rainfall elution, evaporation and pH. All these influences have been critically examined and quantified for different pesticides in this paper. The steps in processing of tea leaves to black tea or green tea bring about a remarkable reduction in the level of pesticides in the ultimate product. The final drying step, which requires more than 100 degrees temperature, has the highest influence. Most of the pesticides residues undergo distillation during water loss and severe thermo degradation with the very high temperatures used for tea drying. The author makes a strong case foranalyzing tea brew as the yardstick forsetting pesticide residue limits rather then the current MRLs in the made tea. The brew contains only 40- 60% pesticide load of dry tea and is the ultimate product for human consumption.

Item Type: Article
Subjects: Nutraceuticals
Depositing User: Dr. Aparna Maitra Pati
Date Deposited: 27 Dec 2011 06:24
Last Modified: 08 Feb 2012 11:17

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