Inactivation of Microorganisms and Enzymes in Foxtail Millet Takju by High Hydrostatic Pressure Treatment

초고압 처리에 의한 좁쌀탁주의 미생물 살균 및 효소 불활성화

  • Jwa, Mi-Kyung (Department of Food Science and Engineering, Cheju National University) ;
  • Lim, Sang-Bin (Department of Food Science and Engineering, Cheju National University) ;
  • Mok, Chul-Kyoon (Department of Food and Bioengineering, Kyungwon University) ;
  • Park, Young-Seo (Department of Food and Bioengineering, Kyungwon University)
  • 좌미경 (제주대학교 식품공학과) ;
  • 임상빈 (제주대학교 식품공학과) ;
  • 목철균 (경원대학교 식품생물공학과) ;
  • 박영서 (경원대학교 식품생물공학과)
  • Published : 2001.04.30

Abstract

High hydrostatic pressure was applied to Foxtail Millet Takju to investigate the effects of high pressure on inactivation of microorganisms and enzymes. Total bacteria, lactic acid bacteria and yeast in untreated Takju were $6.8{\times}10^7,\;1.3{\times}10^8\;and\;8.4{\times}10^7\;CFU/mL$, respectively. Total bacterial count in Takju reduced to $2.2{\times}10^5\;CFU/mL$, while lactic acid bacteria and yeast were sterilized completely when heated at $65^{\circ}C$ for 30 min. Lactic acid bacteria and yeast decreased with the increase of treatment pressure, and pressurization of 400 MPa for 10 min at room temperature sterilized completely the lactic acid bacteria and yeast in Takju. Total bacteria were not sterilized with pressurization of even 600 MPa at room temperature. Total bacteria were completely sterilized at $66^{\circ}C/400\;MPa/60\;min\;and\;66^{\circ}C/600\;MPa/10\;min$. Pressurization of Takju caused a partial inactivation of ${\alpha}-amylase$, and after pressurization at 600 MPa for 10 min at room temperature, 73.2% of the original activity remained. The activity of glucoamylase increased with the increase of treatment pressure. Treatment at $66^{\circ}C/400\;MPa/10\;min$ reduced the activity of ${\alpha}-amylase$ by 59.7% and glucoamylase by 20.5%. ${\alpha}-Amylase$ was inactivated to less than 1.2% of the original activity at $66^{\circ}C/600\;MPa/30\;min$.

Keywords

Foxtail Millet Takju;high hydrostatic pressure;pasteurization;enzyme inactivation