Abstract: This study was done to determine the polyphenol components in freshly prepared green tea from lowland tea-leaf (TL) and tea-leaf stalk (LS) compared to the components found in commercial green-tea (GT). Extraction with methanol gave the highest yield of polyphenol. Determination of total phenols using Folin-Ciocalteau method showed that the powdered extract of LS has the lowest amount of polyphenol (16.57%) compared to TL (28.42%) and GT (26.53%). Although all the expected catechins were present in LS, the concentration were lower than the amount found in GT and TL. Study on the antioxidant activity of tea polyphenol on the quality of oil emulsion showed that the LS polyphenols (at 200ppm) has similar characteristics to BHA (200ppm). The performance of 200ppm TL and GT were much better. Tea polyphenol can maintain the quality of the oil emulsion for more than 40 days. In the presence of pro-oxidant (20ppm Cu2+), the emulsions containing LS extract and BHA became rancid after 4 days storage, while those admixed with 200ppm GT and TL extracts were better protected. As a conclusion, the data obtained suggest that the antioxidative performance of tea polyphenol extract is a better than synthetic antioxidants.
Osman, H. , B. C. Lee and L. L. Fong , 2004. The Polyphenol Profile and Antioxidation Potential of Tea Leaf Stalk Waste from Lowland Tea Plantation . Journal of Food Technology, 2: 202-206.