The development of rancidity in soybean oil has been studied by gas chromatography (GC), peroxide value (PV) and sensory evaluation. The GC method has been adapted from previous methodology and another type of column packing has been used for the purpose. The GC peaks have been treated as one whole group, and and oxidation value (OV) has been computed by means of an internal standard (n‐octanol). The OV’ have been correlated with the PV’s. The flavor of soybean oil and a blend of 50% soybean oil and 50% hydrogenated soybean oil, both kept at 60 C for varying lengths of time, was evaluated by a panel and the results have been presented in a new graphical form. A relationship between the OV and the flavor of the fat has been demonstrated. The merits of the method are discussed.

Summary The separation of methyl esters of octadecenoic acids by G.L.P.C. on a capillary column is shown for a sample of hydrogenated commercial vegetable oil. Comparisons are made with a regular packed column G.L.P.C., a capillary column G.L.P.C., and with infrared analysis. Good separation of methyl oleate and methyl elaidate was accomplished, using a capillary column. The amount of elaidate found by G.L.P.C. compared well with thetrans‐acid found by infrared analysis. In addition, a small amount of a component was detected that is possibly another isomer of methyl oleate.

SummaryAnalyses of various natural fats and oils have been compared by G.L.P.C. and ultraviolet spectrophotometry. Good agreement was found for linoleic acid in unhydrogenated samples. The ultraviolet method gave lower results for linolenic acid. For hydrogenated oils the ultraviolet method gave lower results for both linoleic and linolenic acids in most instances where an appreciable amount of these components was present.It is known that the ultraviolet method measures only the naturally occurring isomers of the unsaturated fatty acids while the G.L.P.C. analysis includes all the isomers. This would account for the difference in responce between unhydrogenated and hydrogenated oils by the two methods of analysis.