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Stability of green tea catechins in commercial tea leaves during storage for 6 months.
J Food Sci. 2009 Mar; 74(2):H47-51.JF

Abstract

To help meet the needs of consumers, producers of dietary tea products, and researchers for information on health-promoting tea ingredients, we determined by HPLC 7 catechins [(-)-epigallocatechin (EGC), (-)-catechin (C), (+)-epicatechin (EC), (-)-epigallocatechin 3-gallate (EGCG), (-)-gallocatechin 3-gallate (GCG), (-)-epicatechin 3-gallate (ECG), and (-)-catechin 3-gallate (CG)] in samples of 8 commercial green tea leaves of unknown history sold as tea bags in the United States, Korea, and Japan. The samples were stored at 20 degrees C and sampled at 1 wk and 1, 2, 4, and 6 mo. The following ranges in the initial values (0 controls) were observed (in mg/g tea leaves): EGC and C, 0 to trace amounts; EC, 1.9 to 21.1; EGCG, 13.3 to 113.0; GCG, 0.2 to 1.6; ECG, 5.7 to 50.5; CG 0.5 to 3.7; total catechins 36.5 to 169.7. Statistical analysis of the results and plots of changes in individual and total catechin levels as a function of storage time indicate a progressive decrease in the content in the total levels, most of which is due to losses in the most abundant catechins, EGCG and ECG. Possible mechanisms of degradations of catechins during storage and the possible significance of the results to consumers of tea are discussed.

Authors+Show Affiliations

US Dept of Agriculture, Albany, CA 94710, USA. Mendel.Friedman@ars.usda.govNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

19323750

Citation

Friedman, Mendel, et al. "Stability of Green Tea Catechins in Commercial Tea Leaves During Storage for 6 Months." Journal of Food Science, vol. 74, no. 2, 2009, pp. H47-51.
Friedman M, Levin CE, Lee SU, et al. Stability of green tea catechins in commercial tea leaves during storage for 6 months. J Food Sci. 2009;74(2):H47-51.
Friedman, M., Levin, C. E., Lee, S. U., & Kozukue, N. (2009). Stability of green tea catechins in commercial tea leaves during storage for 6 months. Journal of Food Science, 74(2), H47-51. https://doi.org/10.1111/j.1750-3841.2008.01033.x
Friedman M, et al. Stability of Green Tea Catechins in Commercial Tea Leaves During Storage for 6 Months. J Food Sci. 2009;74(2):H47-51. PubMed PMID: 19323750.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Stability of green tea catechins in commercial tea leaves during storage for 6 months. AU - Friedman,Mendel, AU - Levin,C E, AU - Lee,S-U, AU - Kozukue,N, PY - 2009/3/28/entrez PY - 2009/3/28/pubmed PY - 2009/7/31/medline SP - H47 EP - 51 JF - Journal of food science JO - J Food Sci VL - 74 IS - 2 N2 - To help meet the needs of consumers, producers of dietary tea products, and researchers for information on health-promoting tea ingredients, we determined by HPLC 7 catechins [(-)-epigallocatechin (EGC), (-)-catechin (C), (+)-epicatechin (EC), (-)-epigallocatechin 3-gallate (EGCG), (-)-gallocatechin 3-gallate (GCG), (-)-epicatechin 3-gallate (ECG), and (-)-catechin 3-gallate (CG)] in samples of 8 commercial green tea leaves of unknown history sold as tea bags in the United States, Korea, and Japan. The samples were stored at 20 degrees C and sampled at 1 wk and 1, 2, 4, and 6 mo. The following ranges in the initial values (0 controls) were observed (in mg/g tea leaves): EGC and C, 0 to trace amounts; EC, 1.9 to 21.1; EGCG, 13.3 to 113.0; GCG, 0.2 to 1.6; ECG, 5.7 to 50.5; CG 0.5 to 3.7; total catechins 36.5 to 169.7. Statistical analysis of the results and plots of changes in individual and total catechin levels as a function of storage time indicate a progressive decrease in the content in the total levels, most of which is due to losses in the most abundant catechins, EGCG and ECG. Possible mechanisms of degradations of catechins during storage and the possible significance of the results to consumers of tea are discussed. SN - 1750-3841 UR - https://www.unboundmedicine.com/medline/citation/19323750/Stability_of_green_tea_catechins_in_commercial_tea_leaves_during_storage_for_6_months_ L2 - https://doi.org/10.1111/j.1750-3841.2008.01033.x DB - PRIME DP - Unbound Medicine ER -