Increasing fungi amyloglucosidase activity by high pressure homogenization

High pressure homogenization (HPH) was recently described as a process able to improve the activity of some enzymes; therefore, the HPH effects on amyloglucosidase (AMG) were investigated. Enzyme solution at pH 2.9, 4.3 and 6.5 were processed at pressures of 0 (just sample circulation on the equipment), 500, 1000, 1500 and 2000 bar and the HPH effects were determined through the enzyme residual activity measured at 35, 65 and 80 degrees C. Results at 35 degrees C showed no relative changes on AMG activity after HPH up to 2000 bar for the three evaluated pH. Similarly, at 65 degrees C (optimum temperature), native and homogenized enzyme at pH 2.9 and 6.5 showed no significant activity changes. On contrary, when enzyme was homogenized at pH 4.3 and its activity evaluated at optimum temperature, a significant activity increase (5-8%) was observed after homogenization at pressures of 1000 bar and above. At 80 degrees C, it was observed an AMG relative activity increase after HPH for the three evaluated pH. Sample homogenized at pH 2.9 showed a gradual and significant activity increase, reaching a maximum increment of 100% after homogenization at 2000 bar with reference to the native enzyme. At pH 4.3 and 6.5, homogenization up to 1000 bar resulted on a significant AMG activity increase of around 20 and 30%, respectively. Therefore, the results highlighted that HPH can increase AMG activity, being dependent on the pH of enzyme solution and the applied pressure. Also, it was observed that process can change the AMG activity at different temperatures, being especially interesting when AMG activity at high temperature is required. Industrial relevance: Two important application of amyloglucosidase are the starch saccharification to obtain corn syrup and the use in juice processing aiming to prevent turbidity and viscosity enhancement caused by unripe fruit. The HPH is suggested to process the enzyme prior to application, to increase its activity at high temperature with consequent time and energy economy during saccharification process. Also HPH is a promising non thermal methodology applied to stabilize juices microbiologically and physically, through particle size reduction and the high stability of amyloglucosidase during HPH process can be important to guarantee the effectiveness of amyloglucosidase during and after HPH. (c) 2012 Elsevier Ltd. All rights reserved.