When E0/Oil0 was 1%, the reaction was very slow if compared to the other two cases and, after 9 h, the concentration of esters was 30% lower than concentration obtained with 5%. This aspect is more evident in Fig. 5, where final conversion is reported for the commercial oil. When E0/Oil0 was 1%, final conversion was 33%, whereas 46–47% was reached in the other two cases. Trends with 3% and 5% were very similar. A E0/Oil0 value of 5% gave only a slight increase in concentration of products, consequently the choice of operating with 3% of biocatalyst respect to initial mass of oil could be considered optimal for an economical and technical point of view.