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Polyphenolic composition and in vitro antioxidant activities of native‐ and tannase‐treated green tea extracts
Author(s) -
Ong ChongBoon,
Annuar Mohamad S. M.
Publication year - 2017
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/ijfs.13331
Subject(s) - tannase , chemistry , polyphenol , dpph , antioxidant , gallate , epicatechin gallate , food science , composition (language) , green tea , epigallocatechin gallate , green tea extract , chromatography , biochemistry , nuclear chemistry , gallic acid , linguistics , philosophy
Summary The antioxidant activities of native‐ and tannase‐treated green tea extracts along with their major polyphenol components were investigated. The polyphenolic content and composition of the tea before and after tannase treatment were determined by liquid chromatography coupled with mass spectrometry ( LC ‐ MS ). Approximately 99% of the (−)‐epigallocatechin gallate ( EGCG ) and (−)‐epicatechin gallate ( ECG ) in green tea extract were converted by tannase to (−)‐epigallocatechin ( EGC ) and (−)‐epicatechin ( EC ), respectively, after 30 min. Biotransformed green tea exhibited a significantly higher DPPH ˙ radical scavenging activities than native green tea ( EC 50 value of 0.024 ± 0.001 and 0.044 ± 0.001 mg mL −1 , respectively). Kinetic parameters such as scavenging rate and stoichiometry were calculated. The rate of DPPH ˙ radical scavenging activities for tannase‐treated green tea extract was shown to be higher than native green tea extract.