Oleogel is a semi-solid oil in which solid particles are dispersed in liquid oil. The formation of crystals in oil is a challenge in the gelation of oleogel and oleogel emulsion. The distortion of crystals occurs due to crystal lattice defects, which deteriorates the crystallinity. Furthermore, there are few studies comparing the gelation formation using different emulsifiers. In this study, we investigated the difference in crystallinity and storage stability of oleogel and oleogel emulsion produced by using different emulsifiers.
For preparation of oleogel, palm oil, canola oil, and emulsifiers were heated and dissolved at 85°C, and three stages of cooling and stirring were performed. (i) Stirring at 2000 rpm until the temperature reached 55°C (ii) Cooling while stirring at 4000 rpm and continue for 15 minutes (iii) Stirring with a medicine spoon for 3 minutes. For preparation of oleogel emulsion system, water heated to 85°C was added to the emulsion, and cooling and stirring were performed in the same manner. Unsaturated monoglyceride (UMG) and saturated monoglyceride (SMG) were used as emulsifiers, and a comparison was made between a sample 0.5% UMG alone and another sample containing 0.5% UMG and 0.5% SMG. Diffraction peaks of the crystals in the samples were measured using synchrotron radiation X-ray diffraction method (SR-XRD), and the crystal distortion and crystal quantity were analyzed. Oil-off was measured for storage stability.
The diffraction peaks of the oleogel and oleogel emulsion were confirmed to be β’ crystals. The oleogel and emulsion were more stable when SMG and UMG were added. The oleogel with both SMG and UMG showed less crystal distortion than the one containing only UMG. The oleogel emulsion with SMG and UMG showed grater crystal quantity than the one containing only UMG. According to these results, we hypothesized that adding SMG contributes to suppressing crystal distortion and increasing crystal quantity. These are related to the stabilization of oleogel and emulsion. In the presentation, we will report on the correlation between SMG and the stability of oleogel and emulsion.