The study of anti-oxidant activity and pesticide residues in ready-to-drink tea products
Abstract
The consumption of healthy beverages has been popular and there are wide varieties of choices. One of them is a ready-to-drink tea product. Tea is divided into four types that are based on the manufacturing process including green tea, black tea, oolong tea, and white tea. The major bioactive compound of tea is polyphenol (catechin) which has anti-oxidant and health promoting effects. However, food safety regarding pesticide residues in tea beverage should be a concerned issue. Therefore, the objectives of this study were to examine anti-oxidant activity and residues of pesticides in ready-to-drink tea products. The twenty samples (green, black, oolong, and white tea) were randomly selected based on popular brands and various flavors. The pesticide residues was analyzed by GT test kit and the anti-oxidant activity was examined by Oxygen Radical Absorbance Capacity (ORAC) and Ferric Reducing Anti-oxidant Power (FRAP) assay. The results found that four types of ready-to-drink tea products in the market still have anti-oxidant activity. The highest total anti-oxidant activity was green tea (9.99±0.16 mM TE/100 ml) followed by oolong tea (6.72±0.21 mM TE/100 ml), white tea (5.48±0.15 mM TE/100 ml), and black tea (5.05±0.15 mM TE/100 ml) respectively. Moreover, the result showed that some of green and black tea samples were contaminated by pesticide residues at a safe level but oolong and white tea were not contaminated. Therefore, the consumption of ready-to-drink tea products remains to benefit of anti-oxidants. However, consumers should be concerned about the amount of sugar, tannin and caffeine, as well as pesticide residues in tea.
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