Moisture level and particle size of soybeans, peanuts and cottonseed were correlated with the extraction rate and yield of oil when extracted with supercritical carbon dioxide (SC‐CO2) at a constant temperature (50 C) and pressure (8000 psig). The rate of extraction and ultimate oil yields were quite low with cracked soybeans. However, good extraction rates and nearly theoretical oil yields were obtained from ground or thinly flaked (<0.010″) seeds. Moisture levels between 3% and 12% had little effect on extracability. Oil composition was not influenced by either parameter. Scanning electron microscopy was used to study seed structure before and after extraction with SC‐CO2. Micrographs of SC‐CO2‐extracted seeds were similar to hexane‐extracted seeds.

Eight different vegetable oils obtained commercially were analyzed for volatiles by capillary gas chromatography (GC). Volatiles generated in a GC static headspace sampler at 180 C were injected automatically onto a chemically bonded capillary column. Only a small number of GC peaks of low intensity were observed in the fresh samples, which varied in peroxide values from 0.2 to 3. Several major peaks were evident in the oils aged eight and 16 days at 60 C with peroxide values ranging from 16 to 65. Thirty-four GC peaks were identified on the basis of relative retention time of reference compounds and on the basis of gas chromatography-mass spectrometry (GC-MS). Volatile compounds identified were those expected from the autoxidaion of principal unsaturated fatty acid components of each vegetable oil tested. The relative concentrations of volatile components increased with the level of oxidation as determined by peroxide value.

To develop new knowledge on undesirable flavors affecting the quality of foods containing polyunsaturated lipids, we investigated the volatiles in soybean oil oxidized at different conditions by three capillary gas chromatographic methods: (a) direct injection (5 min heating at 180 C); (b) static headspace (20 min heating at 180 C, pressurizing for one min), and (c) dynamic headspace (purging 15 min at 180 C onto a porous polymer trap, desorbing from trap for five min). A fused silica column was used with bonded polymethyl and phenyl siloxane phase. At peroxide values between 2 and 10, the major volatile products found in soybean oil by the three methods were pentane, hexanal, 2‐heptenal, 2,4‐heptadienal and 2,4‐decadienal. The intensities of each volatile compound varied with the analytical methods used.