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KMID : 1007520000090040214
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Food Science and Biotechnology
2000 Volume.9 No. 4 p.214 ~ p.217
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Effect of Heat Processing on the Chemical Composition of Green Tea Extract
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Lee, Lan Sook
Kim, Sang Hee/Han, Dae Seok/Park, Jong Dae
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Abstract
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The changes in chemical composition of green tea extract upon heat processing were studied. Fresh tea leaves after harvest were processed into roasted green tea through commercial methods and extracted with 80℃ distilled water at a ratio 1/100 (tea leaves/ water). The green tea extract was heat-processed in a boiling water bath for 30 min and was analyzed for its changes in caffeine, catechins and free amino acid contents. Neither caffeine nor free amino acid contents changed significantly during heat processing. However, epicatechins decreased significantly with the increase of catechins. Total catechins of green tea extract slightly decreased from 77.25 to only 73.45㎎/100 mL. Thermal treatment of catechin compounds prepared from the authentic reagents showed that epicatechins with a 2,3-cis configuration were much more unstable to the heat treatment than catechins with a 2,3-trans configuration. The rapid epimerization of epicatechins resulted in the increase of catechins which epimerized slower under the same heat condition.
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