Natural antioxidants as food and beverage ingredients - Natural Food Additives, Ingredients and Flavourings - page 112

Fig. 5.7 Tea catechins.

EGC, 12% ECG and 10% EC) (Tang et al. 2000). Koketsu and Satoh (2007)
showed that a slightly different green tea catechin composition (25.1% EGCG,
19.3% GC, 16.7% GCG, 16.1% EGC, 8.1% ECG 5.5% EC and 5.2% (+)-catechin)
was more effective than tocopherols and BHA in certain applications.
There have been occasional reports on a prooxidant effect resulting from tea
extracts. Green tea extracts have been reported to have prooxidant effects in seal
blubber oil and menhaden oil (Wanasundara and Shahidi 1998) and in a
deoxyribose oxidation system initiated by Fe 3+ and H 2 O 2 (Yen et al. 1997). Huang
and Frankel (1997) attributed the prooxidant effect to variations within the
stability, reducing potentials, and partitions between different phases of a lipid
system of the various tea catechins.

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Other plant and fruit extracts
Phenolic antioxidants exist in a wide variety of fruits and plants. Many studies
have reported extraction and isolation of such compounds from various sources,