Variations of quality characteristics among oils of different soybean varieties

A study was carried out to evaluate the variation of quality attributes among oils from different soybean varieties (Bovender special, Foster and F-8827).Oils were extracted using n-hexane as solvent. Results indicated that contents of seed oil among the tested varieties varied from 15.85% to 19.49%, moisture 8.4-10.2%, protein 41.67-45.64%, fiber 6.6-7.6% while ash 5.5-6.9%. The physical and chemical characteristics among the tested oils varied as: color (4.2-5.3R + 40-50Y), iodine value (119-128 g of I/100 g of oil), refractive index (1.4590-1.468), density (0.8698-0.8712 g/cm3 at 36 °C), free fatty acid content (0.39-0.67% as oleic acid), saponification value (181-187 mg KOH/g) and unsaponifiable matter (0.42-0.74%). The oxidation parameters including peroxide value, conjugated dienes and conjugated triene were recorded as 1.80-2.64 meq/kg, 0.41-0.65 and 1.50-1.91, respectively. The fatty acid composition showed the presence of palmitic acid (11.00-13.50%), stearic acid (3.02-4.90%), oleic acid (22.60-24.00%), linoleic acid (49.03-53.00%) and linolenic acid (6.50-8.00%). The amounts of α, γ and δ-tocopherols ranged from 66.5 to 90.7 mg/kg, 907.5-1011.9 mg/kg and 399.8-411.5 mg/kg, respectively. Results indicated a significant variation for most of the physicochemical parameters among three soybean oils which can be mainly linked to the specific genetic makeup of each variety as well as the agro-climatic conditions of the harvest.