Effect of extracting solvents on physicochemical properties of vegetable seed oils and their suitability for industrial applications

Abstract

The effects of extracting solvents on the physicochemical properties of vegetable oils extracted from four oil seed plants, namely Dennettia tripetala, Dacryodes edulis, Cola rostrata, and Persea americana, were studied. Vegetable oils were extracted using the Soxhlet method. The oils were used for determining % yield, acid value (AV), iodine value (IV), saponification value (SV), electrical conductivity (EC), and pH. The results revealed that the range of the mean % yield of oils extracted using hexane, carbon tetrachloride (CCl4), petroleum ether, acetone, and methanol, respectively, were 7.5-12.0, 9.0-22.0, 7.5-27.5 and 12.0-37.5 for the four oil Seeds respectively. Mean AVs of oils in mg KOH/g across the solvents were 3.1-3.7, 3.1-3.8, 2.5-3.9 and 2.4-2.8 for Cola rostrata, Dacryodes edulis, Dennettia tripetala and Persea americana respectively. Mean IVs of oils in gI2/100 g across the solvents were 33.25-33.97, 33.06-33.35, 32.06-33.76 and 33.00-34.00 for the four oil seeds, respectively. Mean SVs in mg KOH/g across the solvents were 191.00-197.44, 190.74-198.31, 194.11-202.52, and 182.23-199.44, respectively. Mean EC values ranged 0.31-0.32, 0.30-0.33, 0.30-0.33, and 0.31-0.32 μS/cm across the solvents, respectively. Mean pH values ranged from 6.1-6.4, 4.6-6.3, 6.2-6.4, and 6.1-6.3 across the solvents for the oils, respectively. The AVs of the oils suggest that they are edible oils, the IVs classify the oils as non-drying oils suitable for paint making, and SVs reveal that the oils are good for soap making. Hexane, petroleum ether, and CCl4 are suitable for oil extraction industrially, while D. edulis, D. tripetala, and P. Americana oils are economically viable oil resources due to their high percentage yield, SV and IV.