Polymorphic Behavior of Palm Oil and Modified Palm Oils

概要

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Refined, bleached and deodorized palm oil, its purified palm triacylglycerol (PTG), palm olein (PO), palm stearin (PS) and high melting palm stearin (HMPS) fractions as well as randomized palm oil (RP) and its high melting randomized palm stearin (HMRPS) fractions were solidified at 5°C and kept isothermally at 10, 20 and 30°C for 60 days. X-ray diffraction showed that PTG was in β form crystals, while palm oil and RP were in both α- and β forms at 5°C. In HMPS and HMRPS, the higher percentage of β-transformation was observed with a higher content of trisaturated triacylglycerols and at a higher temperature. RP transformed from β to the intermediate form crystals during prolonged storage. Other fats were stable in β form crystals. Palm oil, RP, HMPS and HMRPS exhibited long-spacing values between those of tripalmitin and tristearin in α, β and β modifications, respectively. This confirms that palm oil and its modified oils form a double-chain-length conformation.