ABSTRACT
In this study, the efficiency of enzymatic esterification and homogenous acid esterification for the reduction of Free Fatty Acid (FFA) content of acid rice bran oil (47 mg KOH g−1) was studied. Further, alkaline transesterification of the pretreated oil mixed with sunflower oil (to achieve FFA content ≤2%) was conducted to maximize fatty acid methyl esters (FAME) production. Homogeneous acid esterification was conducted at respectively 65°C and 45°C, using 2 wt.% and 4 wt.% of H2SO4 as catalyst and 9:1 methanol:oil molar ratio. Enzymatic esterification was performed at 35°C using a 6:1 molar ratio of methanol:oil and 5 wt.% of catalyst. Homogenous acid esterification allowed to achieve the highest acid value reduction (92%), although enzymatic pretreatment alone allowed to obtain the highest FAME content (86 wt.%) compared to acid catalyzed process (41 wt.%). The obtained results show potential of this alternative raw material for bioenergy purposes.
