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Effects of Gamma Irradiation on the Biological Activity of Green Tea Byproduct Extracts and a Comparison with Green Tea Leaf Extracts
Author(s) -
Lee Na Young,
Jo Cheorun,
Sohn Sang Hyuk,
Kim Jae Kyung,
Byun Myung Woo
Publication year - 2006
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2006.00017.x
Subject(s) - dpph , chemistry , food science , antioxidant , green tea , scavenging , biological activity , tyrosinase , biochemistry , in vitro , enzyme
Green tea byproduct extract powder, a major byproduct of the green tea industry, was prepared and investigated for its biological activities after a gamma‐irradiation treatment for the purpose of a brightened color. The color, total phenolic contents, antioxidative activity, tyrosinase inhibition activity, cancer cell proliferation inhibition effect, and antimutagenicity were measured and compared with those of a green tea leaf extract powder. Hunter L* values of the irradiated green leaf and byproduct extracts were increased in a comparison with the nonirradiated extracts. The contents of total phenolic compounds of the green tea leaf and byproduct extracts were 424.2 ± 11.45 and 335.5 ± 18.65 mg/g of sample, respectively. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity of the 20 ppm green tea leaf and byproduct extracts were 68.2% and 57.6%, respectively. Ferric‐reducing ability of the samples showed similar results to the DPPH radical scavenging capacity. The samples showed an inhibition of tyrosinase and also a cancer cell proliferation inhibition effect. Especially, the antimutagenicities of the byproduct extracts showed a strong inhibition effect (96.20% and 57.77%) on 3‐amino‐1,4‐dimethyl‐5H‐pyrido[4,3‐b]indole (Trp) and 2‐nitrofluorene (NF), respectively. Results indicated that, although the biological activity of green tea byproduct extracts is less than that of green tea leaf extract, it may be a potential source of a functional ingredient. In addition, irradiation can be applied to improve the color and biological activity of the material.