At the Fat Stability Committee of Japan Oil Chemists' Society, the results of fat thermal oxidative stability were previously reported. The results of collaborative tests on fat-frying stability are presented in the present paper. Soybean, rapeseed, palm oils, and lard were examined at 180°C under continuous water spraying and heat application. Carbonyl, anisidine, and acid values and polar compounds of the frying oils were determined. The carbonyl value and polar compounds increased linearly. The relation of foaming during fat-frying with variation in the carbonyl value or polar compounds is discussed. It may be possible to assess fat-frying stability on the basis of these two parameters under continuous water spraying and heat application.
The bahavior of sterols and sterylglycoside (SG) in edible oil manufacturing was investigated. Sterols in rape seed and sesame seed could be almost completely isolated from seeds with oil. But only 25% of SG in rape seed and 60% in sesame seed were isolated from seeds. The amounts of sterols in sesame seed oil did not change during manufacturing, whereas 22% of free sterols in rape seed oil was removed mainly in deodorization. The formation of dehydrated sterols in rape seed oil was confirmed during deodorizing and bleaching. More than 99% SG in rape seed oil was removed with phospholipid in hydration and deacidification but 10% of SG in sesame seed oil remained in the final product.
The effects of fatty acid (m=816) and alcohol (n=818) portions in sodium 2-sulfonato-fatty acid higher alkyl esters [CmH2m+1CH (SO3Na) COOCnH2n+1] on monolayers were investigated. Monolayers were converted readily to condensed monolayers with an increase in total hydrophobic chain length and/or with a decrease in difference between two hydrophobic chain lengths. The transition pressure at which an expanded monolayer changed to a condensed monolayer increased with temperatures. The temperature at which the expanded monolayer began to form, i.e., the melting point of the monolayer (Tm), was lower than the melting point (Tc) of the hydrophobic chain length in the bilayer. Tm increased with increasing total hydrophobic chain lengths and/or with decreasing chain length difference.
The crystallization behavior of ternary triacylglycerol (TAG) mixtures of POP (2-oleoyl-1, 3-dipalmitoylglycerol), POS (2-oleoyl-1-palmitoyl-3-stearoylglycerol), and SOS (2-oleoyl-1, 3-distearoyl-glycerol) was examined using high purity materials obtained by preparative HPLC. Seventy three samples were prepared by mixing TAGs and dissolved in acetone. Crystallization was carried out by evaporation of acetone at low pressure, and the crystals were aged at 30°C for 6 months. From the result of DSC analysis of the aged samples, the melting behavior of ternary mixtures was clarified and found related to optimum usage of vegetable fats in chocolate manufacturing.
For clarification of the transport mechanism of lipids from host mouse to ascites tumor cells, host mouse serum and ascite fluid were analyzed. In the host mouse, high concentration of VLDL and HDL and a low concentration of LDL were observed. In ascite fluid, relatively high LDL concentration and lipoprotein lipase activity were detect-ed. Ascite tumor cells may be concluded to incorporate LDL via the LDL receptor and FFA by membrane permeation.
Pork and sardine were fried in soybean oil and the amounts of cholesterol that migrated to the frying oil from pork and sardine were determined by preparative thin-layer chromatography and gas chromatography. A model experiment on the decomposition of tocopherol in oil was carried out and the influence of cholesterol, pork fat, and sardine oil on oil deterioration was assessed. Soybean oils containing cholesterol, pork fat, and sardine oil were heated in glass tubes at 180°C. Increase in cholesterol content in frying oil was observed during frying. Addition of cholesterol failed to prevent the deterioration of oil. The sardine oil accelerated the deterioration of oil and decomposition of tocopherol in oil.