Insight into the influence of plant oils on the composition of diacylglycerol fabricated by glycerolysis and esterification

Abstract

Thirty plant oils are utilized for preparation of value-added DAG by esterification and glycerolysis with glycerol to simultaneously clarify the source-structure-composition relationship in order to increase DAG production and reduce separation process in this investigation. It is found that the dominant DAG components of linoleic acid-rich oils are dilinolein (DL, ECN=28) and linoleoyl-oleoyl glyceride (DOL, ECN=30), and oleic acid-rich oils mainly comprise DOL and diolein (DO ECN=32), whereas DAG from the oils with the close ratio of linoleic/oleic acid dominantly contains the DL, DOL and DO species. The constituents of DAG from the oils rich in unsaturated fatty acid (oleic + linoleic + linolenic acid ≥ 80%) are occupied by the dilinolenin (DLn, ECN=24), dilinoleoyl-linolenoyl glyceride (DLnL, ECN=26) and DL. Visualization and three-dimension structure optimization shows that the DLn, DL, DOL and DO molecules have the lower steric energy. The molecular docking simulation reveals that DAG molecule is mainly interacted with the active pocket (Thr40-Ser105-Asp134-Gln157-His224) of Novozym 435 by O···H bond. This investigation not only provides a deep insight into the source-structure-composition relationship of value-added DAG-rich oils from glycerol as byproduct in biodiesel industries and plant oils derived from agro-industrial residues in food industry, but also discloses the interaction mechanism DAG molecule and Novozym 435.