The viscosities of 12 vegetable oils were experimentally determined as a function of temperature (5 to 95°C) by means of a temperature-controlled rheometer. Viscosities of the oil samples decreased exponentially with temperature. Of the three models [modified Williams-Landel-Ferry (WLF), power law and Arrhenius] that were used to describe the effects of temperature on viscosity, the modified WLF model gave the best fit. The amounts of monounsaturated FA or polyunsaturated fatty acids (PUFA) highly correlated (R 2 > 0.82) with the viscosities of the oil samples whereas poor correlations (R 2 < 0.17) were obtained between viscosities and the amounts of saturated or unsaturated FA. An exponential equation was therefore used to relate the viscosity of these vegetable oil samples to the amounts of monounsaturated FA or PUFA. The models developed are valuable for designing or evaluating systems and equipment that are involved in the storage, handling, and processing of vegetable oils.

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Experimental data on sorption isotherms of gari and winged bean seeds were used to determine their thermodynamic functions (heat of vaporization, spreading pressure, net integral enthalpy and entropy). The heat of vaporization of both products reduced with increase in moisture content and approached that of saturated water at moisture contents of about 15%. Within the moisture content range of 2.0 and 18.0%, the net integral enthalpy and net integral entropy of gari were respectively higher and lower than those of winged bean seeds. The maximum net integral enthalpy for gari was 556 kJ/kg and was 335 kJ/kg for winged bean seeds. The difference in the values of the thermodynamic functions were attributed to the higher amount of oil/fat in winged bean seeds and the presence of gelatinized starch in gari.