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Green tea is a richer source of phenolics than is white tea, but the extraction efficiency of these compounds strongly depends on the time of extraction and the solvents used. The extraction of to- tal polyphenols and flavonoids from white tea leaves is much slower than is the extraction of the same compounds from green tea leaves but the extraction of these phenolics from white tea by water could be accelerated by addition of lemon juice. In this case, there is no significant difference in phenolic content be- tween white and green tea extracts after 5 min of extraction (usu- ally the recommended infusion time for tea preparation). HPLC analysis of catechins, which are the dominant phenolics in tea leaves, confirmed the fact that green tea is a richer source of
858 G. Rusak et al. / Food Chemistry 110 (2008) 852–858
phenolics than is white tea. This analysis also confirmed that 40% ethanol is the most effective among the solvents tested in the prolonged extraction of catechins, especially in the extraction of EGCG, the dominant catechin in tea leaves. The extraction effi- ciency of catechins from green tea was significantly affected by the form (bagged or loose) of tea used, whereas this effect was shown to be not statistically significant for white tea. The extrac- tion of these compounds from loose green tea leaves was more effective than was extraction from bagged tea leaves. In general, the extracts of green tea show a higher free radical-scavenging ability. A statistical linear correlation was confirmed between the total polyphenol content and the antioxidant capacity of the extracts of both teas investigated.
Phenolic content and antioxidative capacity of green and white tea extracts depending on extraction conditions and the solvent used
Gordana Rusak a,*, Draz#711;enka Komes b, Saša Likic #769; a, Dunja Horz#711;ic #769; b, Maja Kovac#711; b a Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Croatia
b Department of Food Processing and Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia