Preparation of Diglyceride from Flaxseed Oil by Enzymatically Catalyzed Glycerolysis and Analysis of its Oxidative Stability

Abstract:

Diacylglycerol (DAG) is an important functional lipid with functions of preventing arteriosclerosis and inhibiting fat accumulation. DAG was prepared by enzymatically catalyzed glycerolysis in a solvent-free system using glycerol and linseed oil as the raw materials and Lipozyme CALB lipase as the catalyst to improve the yield of DAG prepared from flaxseed oil and to investigate the oxidative stability of DAG. The effects of substrates molar ratio, reaction temperature, reaction time, initial water content and enzyme loading amount on DAG mass fraction were investigated by single factor experiment. The oxidation stability of DAG prepared by molecular distillation refining from flaxseed oil was studied. The results showed that the yield of DAG reached 47.13% with a purity of mass fraction up to 57.18% after molecular distillation under the molar ratio of glycerol to flaxseed oil of 20∶1 for 10 h reaction at 80 ℃ with the initial water content (mass fraction) of 0 and the enzyme loading (mass fraction) of 2.0% (calculated by mass of substrate). The oxidation stability of DAG prepared from flaxseed oil was significantly improved with the addition of TBHQ (0.20 g/L) as the antioxidant, and its theoretical shelf life was extended from 37 d to 109 d.