U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Produce Safety and Microbiology Research: Albany, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Albany, California Western Regional Research Center Produce Safety and Microbiology Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Friedman, Mendelitem
                                            Levin, Carolitem
                                            LEE, SEUNG-UN - UIDUK UNIV. KOREAitem
                                            KOZUKUE, NOBUYKI - UIDUK UNIV. KOREA
  Submitted to: Journal of Food Science
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 10/25/2008
                                    Publication  Date: 3/20/2009
                                    Citation: Friedman, M., Levin, C.E., Lee, S., Kozukue, N. 2009. Stability of Green Tea Catechins  in Commercial Tea Leaves during Storage for 6 Months. Journal of Food Science. 74(2):47-51.Interpretive Summary: As part of an effort to relate composition of teas to antimicrobial activities against foodborne pathogens, including ongoing studies on inactivation of Salmonella bacteria on peanuts, we noted that tea bags stored for long periods of time lose some their biologically active catechins.  To better define the significance of storage-induced changes, we did a statistical analysis of the results of changes in individual and total catechin levels as a function of storage time of teas sold in the United States, Korea, and Japan.  The results indicate a progressive decrease in the content in individual and total levels of seven catechins during a six-month storage period. The described observations will hopefully stimulate additional needed studies on the stabilities of tea catechins in green and theaflavins in black tea leaves throughout the harvesting, processing, marketing, storage, and consumption of teas and tea products.  The results, based on a collaborative study with a Korean University, suggest that consumers may benefit from knowing the storage history of teas sold at retail.  A manuscript on this subject will be published in the March 2009 issue of the Journal of Food Science.
                                Technical 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 seven 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 eight commercial green tea leaves of unknown history sold as tea bags in the United States, Korea, and Japan.  The samples were stored at 20 °C and sampled at 1 week, 1 months, 2 months, 4 months, and 6 months.  The following ranges in the initial values controls were observed (in mg/g tea leaves): EGC and C, 0 to trace amounts; EC, 1.9-21.1; EGCG, 13.3-113.0; GCG, 0.2-1.6; ECG, 5.7-50.5, CG 0.5-3.7; total catechins 36.5-169.7.  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.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov