Simple enzymatic removal of steryl glucosides from biodiesel results in excellent filterability properties

Biodiesels produced from transesterification of vegetable oils have a major quality problem due to the presence of precipitates, which need to be removed to avoid clogging of filters and engine failures. These precipitates have been reported to be mostly composed of steryl glucosides (SGs), but so far industrial methods to remove these compounds are inefficient or rely in the costly and energy demanding distillation. Here we present an efficient, scalable, and cost-effective method for the removal of SGs from biodiesel, based on the hydrolytic activity of a thermostable β-glycosidase obtained from Thermococcus litoralis.
The enzyme has been tested on crude soybean biodiesel with different levels of SG content. The resulting biodiesel displayed excellent filterability properties, according to Total Contamination (TC), Cold Soak Filtration Test (CSFT), Filter Blocking Tendency (FBT), and Cold Soak Filter Blocking Tendency (CSFBT) tests, performed according to the procedures described in the EN 12662, ASTM D7501, ASTM D2068 and CAN/CGSB-3.524-2011 norms, respectively. The process was successfully scaled up to a 20 ton reactor, confirming its adaptability to industrial settings