Going Green

February 12/Wuxi, China/Science Letter -- According to recent research published in the International Journal of Food Science and Technology, "Green tea is an unfermented tea containing a higher quantity of bioactive components. In this paper, the effects of pulsed electric field (PEF) treatments on the bioactive components (polyphenols, catechins and free amino acids), color and flavor of green tea infusions were studied."

"PEF as a promising non-thermal sterilization technology could efficiently retain polyphenols, catechins and original color of green tea infusions with electric field strength from 20-40kV cm(-1) for 200mu s. PEF treatments caused a significant increase in the total free amino acids of green tea infusions. The total free amino acids increased by 7.5% after PEF treatment at 40kV cm(-1). The increase in total amino acids induced by PEF treatment, especially to theanine, is beneficial for the quality of commercial ready-to-drink green tea infusion products. There was no significant effect of PEF treatment at 20 or 30kV cm(-1) on flavor compounds of green tea infusions. However, PEF treatment caused losses of volatiles in green tea infusions to different extents when PEF dosage was higher than a critical level," wrote W. Zhao and colleagues, Southern Yangtze University.

The researchers concluded, "The total concentration of volatiles lost was approximately 10% after PEF treatment at 40kV cm(-1) for 200mu s."

Zhao and colleagues published their study in the International Journal of Food Science and Technology ("Effects of pulsed electric fields on bioactive components, colour and flavour of green tea infusions." International Journal of Food Science and Technology, 2009;44(2):312-321).

For additional information, contact R.J. Yang, Southern Yangtze University, School Food Science & Technology, 1800 Lihu Rd., Wuxi 214122, People's Republic of China.

From the February 16, 2009, Prepared Foods E-dition