Crystallization behavior of hydrogenated sunflowerseed oil: Kinetics and polymorphism |
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Authors: | M L Herrera |
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Affiliation: | (1) Centro de Investigación y Desarrollo en Criotecnología de Alimentos, Casilla de Correo 553, 1900 La Plata, Argentina |
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Abstract: | Kinetics of crystallization of hydrogenated sunflowerseed oil was studied by means of an optical method. Two different aspects
were examined: the effects of preheating of the molten liquid on induction time of isothermal crystallization and the effects
of cooling rate on the crystallization behavior. Induction time for crystallization was markedly dependent on the crystallization
temperature and the cooling rate selected. Morphology, polymorphism and chemical composition of the crystals were examined.
At all crystallization temperatures, β′-form was found for the first occurring crystals. Long spacings were also similar in
all cases and corresponded to a double chainlength arrangement. The chemical composition of the crystals showed no differences
at either cooling rate. However, the melting behavior was different. At a slow cooling rate, fractionation occurred, and differential
scanning calorimetry diagrams had a broad second endotherm with three peaks, none of which were completely resolved. The polymorphic
transformation rate from β′ to β was slower when induction times were longer. |
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Keywords: | Chemical composition crystallization kinetics morphology polymorphic transformation rate polymorphism thermal behavior |
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