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Plasma Sci. Technol. ›› 2018, Vol. 20 ›› Issue (4): 044008.doi: 10.1088/2058-6272/aaa400

• Plasma Biomedicine • Previous Articles     Next Articles

Influence of pulsed electric field on enzymes, bacteria and volatile flavor compounds of unpasteurized sake

Takamasa OKUMURA1, Taro YAEGASHI2, Takahiro FUJIWARA2 , Katsuyuki TAKAHASHI2, Koichi TAKAKI2 and Tomo KUDO3   

  

  1. 1 Institute of Fluid Science, Tohoku University, 980-8577 Sendai, Miyagi, Japan 2 Department of Systems Innovation Engineering, Iwate University, 020-855 Morioka, Iwate, Japan 3 Washinoo Co., Ltd, 028-7111 Hachimantai, Iwate, Japan
  • Received:2017-09-30 Published:2017-12-21
  • Supported by:

     support by a Grant-in-Aid for Scientific Research (A) from the Japan Society for the Promotion of Science, Grant Number 15H02231.

Abstract:

A pulsed electric field (PEF) was applied to unpasteurized sake at constant temperatures, at which α-amylase was not inactivated. We adjusted the input energy to be identical for the temperatures by changing the number of PEF application, because the current significantly increased with the temperature, even the amplitude of the applied voltage was identical. As a result, the α-amylase was seemed to be inactivated by PEF application, not due to thermal effect. The glucoamylase was significantly inactivated by PEF. Moreover, the acid carboxypeptidase was inactivated by PEF at 4 °C but significantly activated at 25 °C. These results show that the sensitivity of enzyme to PEF application differs depending on the types of enzyme and treatment temperature. On the other hand, the colony number of bacteria was remarkably decreased, but the amount of the volatile flavor compounds was not decreased by PEF application.

Key words: pulsed electric field, enzyme activity, bacteria inactivation, vulnerable molecules, unpasteurized sake, electroporation