pH-Dependent Inactivation of Enzymes by Microbubbling of Supercritical Carbon Dioxide

Abstract

The effect of pH on the inactivation of some enzymes (acid protease, alkaline protease, papain, and glucoamylase) dissolved in McIlvaine buffer by microbubble supercritical (SC) CO₂ treatment was investigated in the range of pH 3 to pH 6. Remarkable inactivation was observed with this treatment at pH less than 4, whereas with gaseous and liquid CO₂ treatments little or no important inactivation occurred. Microbubbling of SC-CO₂ at lower pH was effective at 40-50°C. Microbubbling of SC-CO₂ at pH 3 inactivated completely enzymes at temperatures 25° lower than that of the thermal treatment (65-75°C). The degree of inactivation in acid protease increased with increasing ethanol concentration.