Nie_2015_Appl.Biochem.Biotechnol_177_1176

Non-edible oils are preferred raw materials for biodiesel production. However, the properties of raw materials significantly affect the synthesis process, leading to difficulties to design one process suitable for any kind of raw material. In this study, the composition of five typical non-edible oils was analyzed. The major difference was the content of free fatty acids, reflected from their acid values. The influence of different oils was investigated by using lipase from Candida sp. 99-125. At low lipase dosage and low water content, the conversion was found proportional to the acid value. However, by increasing the water content or lipase dosage, we observed that the conversions for all kinds of oils used in this study could exceed 80 %. Time course analysis indicates that the lipase used in this study catalyzed hydrolysis followed by esterification, rather than direct transesterification. Accumulation of free fatty acids at the very beginning was necessary. A high water content facilitated the hydrolysis of oils with low acid value. This lipase showed capability to transform all the oils by controlling the water content.