An enzymatic process for the removal of steryl glucosides, major contaminants of vegetable oil derived biodiesel

ANDRES AGUIRRE; FLORENCIA EBERHARDT; MAURICIO BRAIA; HUGO MENZELLA; SALVADOR PEIRU

Congreso; SAIB 2014; 2014

Biodiesels are mostly produced from lipid transesterification of vegetable oils, including those from soybean, jatropha, palm, rapeseed, and others. Unfortunately, transesterification of oil produces various unwanted side products, including steryl glucosides (SG), which precipitate and need to be removed to avoid clogging of filters and engine failures. So far, efficient and cost-effective methods to remove SGs from biodiesel are not available. Here we describe the identification, characterization and heterologous production of an enzyme capable of hydrolyzing SGs, and its implementation on a biodiesel treatment process. A steryl glucosidase (SGase) was selected from a family of thermophilic β-glucosidases. The synthetic gene was efficiently expressed and purified from E. coli; and SGase was used to treat soybean derived biodiesel containing 100 ppm of SGs. Several variables of the process were optimized, including temperature, pH, buffer, water content and salinity. Adjustments on the reaction conditions allowed a reduction of the SGs present in biodiesel below 5 ppm. Treatment was successfully scaled from 1 g to 1 ton of biodiesel. The resulting biodiesel was evaluated by the most stringent quality tests with excellent performances. These remarkable results suggest a path for the removal of SGs from biodiesel on industrial scale using an environmentally friendly enzymatic process.