Effect of Process Conditions on the Physico-Chemical Properties of Groundnut Oil Extracted with a Vertical Screw Jack

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Valahia University of Targoviste, Romania


The effect of two process conditions (temperature and heating time) on some physico-chemical properties (pH value, Free Fatty Acid (FFA), saponification value, acid value, refractive index and viscosity) of groundnut oil extracted with a vertical screw jack was investigated. The following equipment were used: a vertical screw jack, digital weighing balance (OHAUS CL Series, Model CL 201, China, accuracy: 0.1), stop watch (Nokia X2-01), and oil bottles and containers. Three levels of temperature (50oC, 60oC and 70oC) and two levels of heating time (5 min and 10 min) were used for processing the groundnut before oil extraction. The experimental design used was factorial experiment in a Randomized Completed Block Design (RCBD) with three replicates. A uniform experimental sample of 100 g per run of prepared groundnut seeds was used as feedstock for oil extraction operation. Samples of oil extracted were analysed for the physico-chemical properties with AOAC (2002) standard procedures. Results showed that the physicochemical properties of extracted oil decreased with increase in temperature from 50oC to 60oC and heating times but later increased at 70oC. The range of values of physico-chemical properties obtained were: 5.05-5.45 for pH value, 3.32-3.43 mgKOH/g for FFA, 1.87-1.95 mgKOH/g for saponification value, 6.65-6.85 mgKOH/g for acid value, 1.443-1.455 for refractive index and 1.44-1.45 cm/sec for viscosity.



process conditions, physico-chemical properties, screw jack, groundnut oil, extraction