Effect of Storage Temperature and Antioxidant Additives on the Color and Physiological Activity of Gamma Irradiated Green Tea Leaf Extract

  • Jo, Cheo-Run (Radiation Food Science and Biotechnology, Korea Atomic Energy Research Institute) ;
  • Byun, Myung-Woo (Radiation Food Science and Biotechnology, Korea Atomic Energy Research Institute)
  • Published : 2003.06.01


Gamma irradiation was used as part of a new processing method to produce a brighter-colored and mild-flavored green tea leaf extract that retained all of its physiological activities. Dried green tea leaf was extracted with 70% ethanol and gamma irradiated at 0,5, 10, 20 kGy. Hunter color $L^{*}$- and $a^{*}$-values were increased with irradiation in a dose-dependent manner, which was a color range from dark brown to bright yellow. However, the irradiation effect gradually disappeared during 3 weeks of storage, with color reverting to that of untreated samples. There was no difference in the radical scavenging and tyrosinase inhibition effect by irradiation. Among antioxidants used, ascorbic acid was the most effective against color reversion. In contrast, cysteine was shown to protect the effect of color change with irradiation. Results indicated that enhanced color of irradiated green tea leaf extract can be effectively controlled by additives such as ascorbic acid and a low storage temperature.e.e.


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