Crystallisation kinetics of rice bran and soybean oils during storage at low temperature

Abstract

Changes in volume and transmitted light intensity of vegetable oils with low melting points, rice bran, and soybean oils, were measured when the oils were cooled at 0.5°C/min to various isothermal hold temperatures in the range of −23 to −35°C and stored at that temperature. Partial crystallisation of components with high melting points was suggested to occur during a cooling process, by the change in transmitted light intensity. During isothermal storage, the volume of the oils decreased stepwise. It was considered that this decrease was attributable to the independent crystallisation of the components with high and low melting points, which crystallised with short and long storage periods, respectively, at a specific temperature. Based on these results, a kinetic model in which the oil was assumed to consist of two groups containing components with high and low melting points, represents the stepwise crystallisation with high accuracy.