Retention of high-value tocols during enzymatic esterification of palm fatty acid distillate using liquid lipase for improving the economics and sustainability of biodiesel production

Abstract

Liquid lipase has recently been gaining popularity in converting secondary lipid feedstocks to biodiesel. However, it was unknown whether enzymatic biodiesel production could affect the retention of high-value phytonutrient(s) in the feedstocks. For the first time, the retention of tocols (a highly potent antioxidant) during enzymatic conversion of palm fatty acid distillate (PFAD) to biodiesel using a low-cost liquid lipase, Eversa® Transform 2.0, was studied. This study investigated the effects of methanol dosage on ester and fatty acid contents alongside tocols retention. The highest ester content (92.03 wt%) was achieved within a short reaction time of 4 h using 2 wt% enzyme concentration and 3:1 methanol-to-PFAD molar ratio. Interestingly, tocols retention was found to be correlated to the extent of fatty acid conversion. The maximum tocols retention was determined to be 91.98%. After vacuum distillation, the tocols content was enriched 25-fold (∼66,000 ppm) in the heavy phase, whereas the ester content increased to ∼96 wt% in a light-colored distillate (biodiesel). In conclusion, it is feasible to efficiently produce high-value phytonutrient(s) alongside biodiesel from secondary feedstock via an enzymatic route using a liquid lipase. The findings from this work provide the industry an opportunity to improve process economics and sustainability of biodiesel production.