Crystallization Behavior of Diacylglycerol‐Rich Oils Produced from Rapeseed Oil

Abstract

We examined the crystallization behavior of high-melting fractions in liquid oil containing high concentrations of diacylglycerols (DAG [80%) (hereafter referred to as DAG-rich oil). By differential scanning calorimetry and optical microscopy at moderate cooling rates, crystallization in the DAG-rich oil was detected at around 6°C. It was found that the crystallization extent increased with decreasing temperatures of crystallization below 0°C. A gas chromatographic analysis was performed on the crystallized fractions, which were separated by filtration at different periods of isothermal crystallization at 3°C. The results indicated that at earlier crystallization periods, the concentrations of 1,3-disaturated DAG such as palmitic and stearic acid moieties (15 min) and 1,3-saturated-unsaturated mixed-acid DAG including oleic acid, palmitic, and stearic acid moieties (15 min-3 h) were predominant. However, the concentrations of 1,3-diunsaturated DAG including oleic acid moiety increased after a crystallization period of 6 h. To clarify the sequential crystallization process of DAG, we examined the binary mixing behavior of principal DAG components occurring in the rapeseed-based DAG-rich oil. It was evident that 1,3-disaturated DAG, 1,3-saturated-unsaturated mixedacid DAG, and 1,3-diunsaturated DAG exhibited immiscible behavior. From these data, basic information on the precipitation processes in DAG-rich oils at chilled temperatures was obtained.

Crystallization and polymorphic behavior of shea stearin and the effect of removal of polar components

“…Peaks for StO, StSt, and PP DAGs have been confirmed by comparison with pure standards. Other peaks are tentatively assigned by comparison with Saitou et al .…”

Production of Diacylglycerol-enriched Oil by Glycerolysis of Soybean Oil using a Bubble Column Reactor in a Solvent-free System

“…The granular crystals might be β form, while the round-shaped crystals might be β polymorph since β form had a larger crystal than β form. Saitou et al had also found that small round-shaped crystals with diameters ranging 5-20 μm observed in DAG-enriched oil at about 6 29 .…”

“…4a, Table 2 . This broad peak peak I might be caused by the different crystallization rates of different DAG components 29 . And peak II was about 5 times larger than peak I, which meant the second crystallization stage formed more crystal fraction than the first one did.…”

Synthesis, physicochemical properties, and health aspects of structured lipids: A review

“…As for DAGs with the same molecular conformation, the melting point increases with increasing fatty acid saturation, as observed in DSC results (heating rate: 1 • C/min) of purified 1,3-dioleoyl-sn-glycerol (26.33 • C), 1-palmitoyl-3-oleoylsn-glycerol (43.63 • C), and 1,3-dipalmitoyl-sn-glycerol (69.70 • C; Xu & Cao, 2017a). In the work of Saitou et al (2012), for example, when DAG-rich oils (DAG: 85.0%) produced from rapeseed oils were cooled at 3 • C, the resultant crystals were mainly composed of 1,3-DAGs instead of 1,2-DAGs. In addition, the DAG fractions have been found to crystallize in a sequential manner with high-melting molecules such as 1,3-disaturated DAGs crystallizing first followed by 1,3-saturated-unsaturated and 1,3-diunsaturated DAGs (Saitou et al, 2012).…”

“…In the work of Saitou et al. (), for example, when DAG‐rich oils (DAG: 85.0%) produced from rapeseed oils were cooled at 3 °C, the resultant crystals were mainly composed of 1,3‐DAGs instead of 1,2‐DAGs. In addition, the DAG fractions have been found to crystallize in a sequential manner with high‐melting molecules such as 1,3‐disaturated DAGs crystallizing first followed by 1,3‐saturated‐unsaturated and 1,3‐diunsaturated DAGs (Saitou et al., ).…”