ABSTRACT
The soapstock oil presents high Free Fatty Acid (FFA) content, being potentially a sustainable alternative feedstock for biodiesel production. In the present work, enzymatic esterification using a suspension of Thermomyces lanuginosus lipase was conducted on pre-treated and untreated acid oil from soapstock derived from the refining of vegetable oil mixtures. The enzyme suspension was prepared by mixing it with a 1 M phosphate buffer (1:10 V/V, enzyme:buffer). Esterification was conducted in an orbital shaking incubator at 40.0°C using a molar ratio of acid to methanol of 1:3, during 24 h at 200 rpm; monitoring was performed at 0, 7 and 24 h. Around 80% FFA reduction was obtained using raw and pre-treated oil, showing that the use of suspended enzyme avoids the need for pretreatment. Fatty Acid Methyl Ester content was determined, indicating that both esterification and transesterification reactions occurred.
