Influence of processing conditions on some physical characteristics of vegetable oil expressed mechanically from Pentaclethra macrophylla Benth kernels: Response surface approach

Abstract

AbstractThe global increase in demand for vegetable oils due to their nutritional, pharmaceutical, and industrial importance necessitates investigation on exploitation of new oil bearing crops. This study was undertaken to determine the influence of processing conditions on physical properties of oil expressed mechanically from African oil bean kernels. Central composite rotatable design of response surface methodology (RSM) at 3‐factors, 5‐levels was adopted; independent variables considered were: moisture content (MC; 8, 10, 12, 14, and 16% dry basis), heating duration (HD; 5, 10, 15, 20, and 25 min), and heating temperature (HT; 50, 70, 90, 110, 130 °C) while dependent variables (physical characteristics) include: oil impurities, density, kinematic viscosity, dynamic viscosity, specific gravity, refractive index, and color; all determined using standard methods. Optimum values were obtained using RSM. Optimum oil quality (0.044%m/m impurity, 0.92 kg/m3 density, 43.86 mm2/s kinematic viscosity, 40.8 mPa s dynamic viscosity, 0.9 specific gravity, 1.469 refractive index, and 7.7 color units) was obtained at 8% db, 11.7 min HD, and 59.3 °C HT. The quality of the expressed oil falls within permissible limits for edible oils and high nutritional importance. The processing conditions influenced the quality of the mechanically expressed African oil bean oil.Practical applicationsAfrican oil bean is an underutilized plant with potentials for meeting increasing global demand for vegetable oil for nutritional and industrial importance. The application/usage of oil is dependent on its quality attributes which is otherwise dependent on processing parameters like moisture content, heating duration, and heating temperature. These factors need to be controlled during oil expression processes to actually the optimum conditions that will yield good quality oil. The degree of influence of the parameters on oil quality is a useful data to vegetable oil processors, food, and agricultural engineers. The quality parameters of the oil were determined and compared with international standard parameters. Mathematical models were developed to predict the yield and quality attributes of expressed oil from African oil bean kernels at various processing conditions.