One‐pot synthesis of fatty acid epoxides from triacylglycerols using enzymes present in oat seeds

Abstract

AbstractIn our previous work we used ground oat (Avena sativa) seeds as an inexpensive source of enzymes for the modification of FA or their chemical derivatives. We have extended this work by observing the products derived from an intact fat and three vegetable oils through the concerted action of oat seed enzymes. A modified reversed‐phase HPLC protocol was devised that allowed the quantification of FFA, epoxy FA, and acylglycerols without derivatization. It was found that the addition of the surfactant deoxycholate or calcium chloride was needed to observe best hydrolysis of TAG to FA. Without an added oxidant, lipase action produced up to 80% by weight of FA at pH 7–9 with small amounts of DAG and MAG. When the oxidant t‐butyl hydroperoxide was added in the presence of deoxycholate, the FA were partially converted to epoxide derivatives (up to 35% by weight). When calcium chloride replaced deoxycholate, only 4% by weight of the product was epoxide derivatives. The highest levels of FA epoxides were generated at pH7, and up to 15% by weight of the product at this pH was epoxymonostearin (monoepoxyoctadecanoylglycerol). The optimal molar amount of t‐butyl hydroperoxide to add with deoxycholate for high epoxide formation was 1.4 to 2.8 times the amount of fatty esters in soybean oil. In no instance were oxidized DAG or TAG detected, demonstrating that a highly specific enzymatic process was responsible for epoxide formation. The epoxide products may be used to produce polyols with high viscosity for grease preparations.