Morphology of monosaturated triacylglycerol crystals in different crystallization procedures
2019
Takeguchi, S. ((The Nisshin OilliO Group, Ltd., Yokohama, Kanagawa (Japan)), (Hiroshima University, Higashi-Hiroshima, Hiroshima (Japan). Graduate School of Biosphere Science)) | Hondoh, H. | Satoh, A. | Aoki, M. | Uehara, H. | Ueno, S.
The morphology of triacylglycerol (TAG) crystals significantly affects the efficiency of their fractionation during the processing of fats and oils to improve their functionality. Large stable crystals, formed by fast crystallization, improve the fractionation efficiency. The purpose of this study was to determine optimal crystallization to improve the morphology of stable β form crystals that are suitable for dry fractionation. The polymorphic transformation behaviors from unstable forms to stable forms were investigated by polarized light microscopy and X-ray diffraction. The solid-solid transformation of unstable α and β’ forms of monosaturated TAGs intoβ forms was investigated. The β form was nucleated in the β’ form and grown, by solid-solid transformation, to a larger crystal to improve its separation efficiency. In contrast, the β form transformed from the α form retained the original morphology of the α form. The size of the obtained β form crystals increased with an increase in the crystallization temperature of the initial β’ forms. The temperature of polymorphic transformation affected the rate of transformation, while the influence of temperature on the size of transformed crystals was limited. We also clarified the influence of the difference in fatty acid chain length of the examined TAGs. The present study demonstrated that crystal morphology can be modified, depending on the crystallization procedure, to improve the fractionation efficiency.
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