Synthesizing Precursors for Functional Food Structured Lipids from Soybean Oil Deodorized Distillates

Abstract

A "green" scheme of synthesizing diglycerides as a means of valorizing an oil processing by-product, specifically soybean oil deodorized distillate (SODD), was established. Different glycerol dosing strategies were implemented in the solvent-free lipase catalyzed esterification of free fatty acids with glycerol within molar ratios of 2-4 and temperatures of 40-60 °C. The process responses were compared with non-dosed systems in this study and other similar processes reported in literature. Better 1,3-diglyceride selectivity at comparable yields were observed with glycerol dosed-systems over non-dosed systems. The presence of molecular sieves negatively affected 1,3-diglyceride selectivity, total diglyceride selectivity and yield. Selectivity of 0.91 ± 0.01 g diglycerides/g (mono + triglycerides), free fatty acid conversion of 57.87 ± 3.46%, and yield of 30.59 ± 1.26 g diglyceride/100 g raw material is obtained with SODD at 40 °C, overall free fatty acid to glycerol molar ratio of 2, 4 wt% Novozyme 435 and 48 h. The process scaled better than most solvent-based ones supported with hygroscopic sorbents in terms of reaction mass efficiency.