Effect of brewing method on antioxidant activity of rooibos tea
[In case someone has wondered how to prepare the red "tea"]
C. FAJARDO-LIRA, Dept. of Family Consumer Sciences, California State Univ., Northridge, 18111 Nordhoff St., 200-D Sequoia Hall, Northridge, CA 91330-8308 and J. Wiederhold, Dept. of Family Consumer Sciences, California State Univ. Northridge, 18111 Nordoff St., 200-D Sequoia Hall, Northridge, CA 91330-8308.
Dietary antioxidants may have a strong effect in the reduction of tissue damage and diseases related to oxidation processes. There is a growing body of research examining the antioxidant content of various teas. Aspalathus linearis, a South African shrub, is used to make a beverage known as rooibos tea. Rooibos tea is growing in popularity as an antioxidant rich caffeine free alternative to green tea and black tea. Previous research has indicated that the antioxidant activity of rooibos tea may be affected by the brewing method but the results have not been conclusive. Our objective was to determine the antioxidant activity of samples of fermented rooibos tea prepared by two different brewing methods using a modified Oxygen Radical Absorbance Capacity (ORAC) assay. Tea leaves of fermented rooibos were used to prepare the tea by either steeping for five minutes or boiling with water for ten minutes. Tea leaves in an amount of 2.5 g were used per 100 ml of water. The ORAC value for the brewed tea samples was determined by using a modification of the method described by Cao and Prior (1999). ORAC values varied from a mean of 725.16 TEµM/g for tea prepared by the steeping method to a mean of 1114.55 TEµM/g for tea prepared by the boiling method. ANOVA analysis revealed a significant difference (P< 0.01) between the rooibos tea prepared by steeping for five minutes and the tea prepared by the boiling method. The ORAC assay was an effective tool to measure antioxidant activity in rooibos tea. Results indicate that tea prepared by boiling for ten minutes had significantly higher antioxidant content than tea prepared by steeping for five minutes. These results suggest that selection of a brewing method may be an important factor for extraction of antioxidant compounds in rooibos tea.
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