The binary phase behaviour of positional isomers of triacylglycerols.

摘要

One method of producing low trans margarines and shortenings is by random chemical interesterification. This process introduces positional isomers of triacylglycerols (TAGs), which may be implicated in the formation of undesirable eutectics. This study investigated the polymorphism, melting and crystallization behavior, microstructure and relative hardness of three binary systems of positional isomers, namely 1, 3 dilauroyl-2-stearoyl -sn- glycerol (LSL)/1, 2-dilauroyl-3-stearoyl -sn- glycerol (LLS), 1, 3 dimyristoyl-2-stearoyl -sn- glycerol (MSM)/1, 2-dimyristoyl-3-stearoyl -sn- glycerol (MMS) and 1, 3 dipalmitoyl-2-stearoyl -sn- glycerol (PSP)/1, 2-dimyristoyl-3-stearoyl -sn- glycerol (PPS) as a function of two crystallization rates. These TAGs are likely to be formed in formulations utilizing fully hydrogenated Canola oil and palm or coconut oils. It is proposed that since TAGs generally crystallize in metastable states, depressions or eutectics may be shifted or mitigated using a processing solution. In this study, eutectic behaviour was observed for the LSL/LLS and PSP/PPS systems, while a monotectic behavior was observed for the MSM/MMS system. Depressions in solid fat content and relative hardness were encountered which did not correlate with the eutectic point but the composition at which they occurred was dependent upon crystallization rate.