Optimization of the Performance of a Vertical Screw Jack for Groundnut Oil Extraction

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University of Ilorin, Nigeria


Groundnut (Arachis hypogaea) is one of the oil seeds in the category of the second most valuable commodity in the world trade. One of the methods of extracting groundnut oil is with the use of mechanical device which offsets some of the problems of traditional and chemical methods of extraction. Most local processors of groundnut oil do not use to or do not know how to put into consideration processing factors/inputs (temperature, heating time, pressure, moisture content and so on) that can lead to better (optimum) oil extraction outputs. This situation is causing low oil yield and low extraction efficiency, high extraction loss and poor quality of oil even when machines are used for extraction. Therefore, this study used a vertical screw jack to extract groundnut oil and also optimize the oil extraction process with the use of Design Expert (8.0.3 version) computer software package. Three levels of temperature (50, 60 and 70oC) and two levels of heating time (5 and 10 min) were used to pretreat seeds in the extraction chamber of the vertical screw jack prior to oil extraction process. The extraction process were estimated for oil yield, extraction efficiency and extraction loss; and oil quality in terms of Free Fatty Acid (FFA), saponification value, acid value, refractive index and viscosity were analyzed. Results showed that, optimum oil yield (29.90%), extraction efficiency (48.12%) and extraction loss (4.23%) were achieved at temperatures and time of heating of 50, 50.21 and 70oC; and 10, 5.02 and 10 min respectively. Temperature of 50oC and time of heating of 10, 10, 10, 5 and 5 min gave optimum values of 3.38 mgKOH/g, 190.26 mgKOH/g, 6.74 mgKOH/g, 1.45 and 1.47 cm/s for FFA, saponification value, acid value, refractive index and viscosity respectively; whereas, optimum value of 5.06 was obtained for pH at temperature of 50.15oC and 9.98 min time of heating.



process conditions, optimization, vertical screw jack, groundnut oil extraction, Design Expert, computer software package