FACTORS AFFECTING THE ELECTRICAL-RESISTIVITY OF SOYBEAN OIL

The electrical resistivity of soybean oil that had been purified to re move polar constituents was determined, and the effect of measuring co nditions and the addition of polar constituents (free fatty acids, pho spholipids, monoglyceride, a-tocopherol, beta-sitosterol, beta-caroten e, peroxides, and water) on resistivity was investigated. For reproduc ible resistivity measurements, voltages in excess of 50 volts and char ging times greater than 120 s were necessary. As temperature was incre ased linearly, the resistivity of the oil decreased logarithmically. F or making comparisons, a temperature of 24 degrees C, a potential of 5 0 volts, and 120 s charging times were chosen. All polar constituents decreased the resistivity of the purified soybean oil, but water, phos pholipids, and monoglycerides had the greatest effects. Water increase d the resistivity-lowering effects of all other constituents except fo r free fatty acids, which were affected by water only slightly. The sy nergistic effect of water was much greater for phospholipids and monog lyceride than for other constituents.