Lyotropic liquid crystals from palm oil-based monoacylglycerols: the effects oftempering and monoacylglycerol concentrations

Lyotropic liquid crystal dispersions made of palm oil-based monoacylglycerols are considered novel wall materials for encapsulation technology, but their stability is often quite low due to late crystallization. To overcome this disadvantage, a tempering step (at 40℃) was applied to the gel phases made of different palm stearin–based monoacylglycerols (distilled and non-distilled) and the formation of lyotropic liquid crystals as well as the rheological properties of their dispersions (7% and 15% gel phases) were investigated. Rheology analysis revealed all lyotropic liquid crystal dispersions were well-fitted with the shear-thinning fluids. Combined with polarized light microscope observation, the obtained results confirmed that the tempering step contributed to enhancing the formation of liquid crystals in dispersion increasing the consistency index. However, some liquid crystals melted during tempering because their onset melting point was lower than the tempering temperature and this phenomenon was more considerable in mixtures having a lipid concentration below 40%. By contrast, unwanted spherulite crystals tended to form after the tempering step in mixtures having a higher concentration of monoacylglycerols.