Enzymatic inactivation of oil palm fruits: comparison of microwave irradiation and steam bath process

Abstract

The study on microwave irradiation and steam batch process to sterilize oil palm fruits is carried out to investigate their effectiveness on lipase inactivation. The inactivation parameters, palm oil quality, and stripping efficiency were evaluated. Evaluation on the inactivation parameters, such as decimal reduction time (D-value) and kinetic constant (k), were conducted to study the sterilization dependency on time and temperature. Microwave sterilization required only 14.085 to 16.949 minutes to inactivate lipase at temperature of 76.5°C (max), while steam batch sterilization required more than 90 minutes to obtained similar level of free fatty acid (FFA) at higher temperature (80 to 105°C). The quality of palm oil was indicated by the concentration of FFA in palm oil. Sterilization of either by microwave irradiation or steam batch sterilization reduced lipase’s activity significantly, which is indicated by FFA concentration of below 1%. Stripping efficiency from microwave sterilization at various power level after 16 minutes were 27% (medium power level), 58.5% (medium high power level), and 61% (high power level), respectively.