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

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. [Display omitted] •High FAME content of up to 92.03 wt% was achieved in 4 h using liquid lipase.•Retention of tocols was correlated to the extent of FFA conversion to FAME.•Highest tocols retention achievable was 91.98%.•Tocols was enriched by 25-fold (∼66,000 ppm) after distillation.•Ester content in distillate increased to 95.80 wt%.