The solubilities of carbon dioxide in soybean oil, olive oil and linseed oil, and those of nitrogen, hydrogen and oxygen in soybean oil were measured at pressures ranging from 0.2 to about 1 atm. of gases and at temperatures between 30 and 70°C. In most cases, the solubility of gases in oils follows Henry's Law, that is, the solubility of gas increases linearly as the pressure of gas increases. Generally, the solubility of gas in oils decreases as the temperature increases, except for the case of oxygen. The solubility of oxygen at 70°C is as large as about twice compared with that of 30 or 50°C. This might be due to the reason that the oil is oxidized slightly by oxygen at higher temperatures. Another expression of the solubility of gas, the Bunsen's absorption coefficient may be calculated as the Henry's Law rules in every case. These coefficients are shown in Table-2. The temperature dependence of logarithms of the Bunsen's absorption coefficients enables the calculation of the differential heats of solution of gases. These values are listed in Table-3. Although the values of the differential heat of solution of carbon dioxide in fatty oils do not vary so greatly with the kind of fatty oils, it seems that the value depends either on the molar volume or on the iodine value of the fatty oils. The theoretical considerations based on the quasi-lattice model of the solution of gas in oil suggests that the effect of variation of the molar volume of fatty oils on the differential heat of solution of gas is negligibly small, and the effect of the iodine value is predominant. In spite of the low solubility of hydrogen in fatty oil, the differential heat of solution is larger than that of other gases. The viscosities of soybean oil under vaccum or at saturation with gas at a definte pressures were also measured. When carbon dioxide is dissolved in oil, the viscosity, or the flow out time of oil, decreases lineally as the amount of dissolved gas increases. But, when nitrogen is dessolved, the flow time of oil is somewhat longer than that under vaccum, slightly exceeding experimental errors. This might be partly due to the larger differential heat of solution of nitrogen than that of carbon dioxide.
This study aims at to elucidate the nature and chemical component of rancid flavor of oils which are differently oxidized and also to discuss the effect on such rancidities by the different fatty acid composition of oils and by the different extent of the oxidation. The flavors of rancid soybean, corn and olive oil were evaluated by the organoleptic method and the natures of their flavors were described. Although the difference in the quality of rancid flavor in these oils was small, the flavor of each oil was rather characteristic; namely the “green” and “fishy” flavor were predominant in rancid soybean oil, “haylike” flavor in rancid corn oil, and socalled “heavy” flavor in rancid olive oil. The chromatographic analyses on the volatile components of these rancid oils showed that these fractions were mainly composed of the degradation products of linoleic acid. A considerable amount of the decomposition products of linolenic acid were seen in the volatiles of rancid soybean oil, while a small amount of the decomposition products of oleic acid, which were scarcely found in other oils, were detected in the volatiles of rancid olive oil. Slight difference in rancid flavor of these oils appears to depend on the difference in the quantity of volatile compounds and also on the difference in the fatty acid composition of original oils. The intensity of rancid flavor in these oils seems to correlate with their peroxide value and is independent of their fatty acid composition.
Fatty acids were obtained from 10 domestic lard (8 Yorkshire and 2 Berkshire), 10 beef tallow and 3 horse fat, and the fatty acid compositions were determined by gas chromatography and the Bomer number was compared. Similar test was also carried out with samples in which these were mixed in various ratios. 1) The presence of pentadecanoic acid was not observed in lard. Beef tallow and horse fat contained this, and this can be detected particularly in beef tallow as its content is over 1%. 2) There is considerable difference in fatty acid composition by the kind, and the C14/C16×100 ratio is between 3.56, and furthermore, it was above 10 in case beef tallow and horse fat. C18:3/ C18:1×100 is between 1.55 but the value for horse fat is between 1525. Consequently, detection is possible from these fatty acid ratios, when mixed over 20% beef tallow and over 10% horse fat in lard and the accuracy is better than the Bomer number. 3) The ratio of C14+C16+C18/C18:2 is between 38 but beef tallow and horse fat can be distinguished only when they are 60 and 40%, respectively, hence the accuracy is less than that of the Bomer Method. 4) C18:1/C18×100 ratio is between 0.93.5 in case of domestic lard and can be used for distinguishing from horse fat (1117), but it is not distinguishable from beef tallow(532). Also, C18/C18:2 cannot be used as it ranges 14, and also as the variance is great.
Authors previously reported that β-glycerylphosphoric acid (β-GP) exhibits antioxidant activity in methyl oleate but it does not decompose hydroperoxides. This report deals further study to elucidate mechanism for inhibition of autoxidation of unsaturated fatty acid esters by phosphate esters. Trimethyl, triethyl and tributyl phosphate (TBP) and β-GP were found as active in unsaturated fatty acid esters at a concentration range from 0.01 to 0.04%. Hexane solutions of methyl linoleate containing the same concentrations of TBP or β-GP showed a new absorption peak at 230 mμ, and the absorbancy at this peak tended to decrease as the concentration of the phosphate esters increased. Furthermore, another absorption bands at 34003350, 1929, 1090, 1050 cm-1 and 880 cm-1 were observed in the infrared region. The results appear to indicate that an interaction of the PO group of the phosphate esters possibly with the α-methylene group of the methyl linoleate molecule results in perturbation of the ir electrons of the double bonds of the latter. Therefore, a possible mechanism for the observed antioxidant activity of these esters involves either such an interaction or the formation of an unstable oil-soluble product as a result of such an interaction in early stages of autoxidation, rather than decomposition of hydroperoxides as has generally' been regarded for, the phosphate esters.
Phase diagrams of ternary systems consisting of decaoxyethylene nonylphenyl ether (NP-10), essential oils different in polarity and water have been studied. From the phase diagrams obtained, six essential oils were classified into two groups, the first group of higher polarity being ethyl phenyl acetate, geraniol and isoeugenol methyl ether; the second group of lower polarity being α-ionone, α-amyl cinnamic aldehyde and limonene. In the ternary system containing the essential oil of the first group, the phase diagram showed that the hardening region decreases gradually and eventually disappears and approaches toward the phase diagram of aqueous binary system of surfactant having more decreased degree of polymerization of ethylene oxide, in accordance with the decrease in the weight ratio of NP-10 to essential oil (S/E ratio). It was also found that the phase diagram of ternary system containing essential oil of the second group showed no disappearance of hardening regions and also the appearance of a new hardening region with the decrease in S/E ratio. The latter phase diagram was quite different with that of binary system of aqueous surfactant.
Effects of feeding two type oxidized oils with and without ethoxyquin were tested for the culture of rainbow trout. One of the oxidized oil was higly peroxidized cod liver oil (P.O.V. 280) and the other was peroxide-decomposed oil prepared by heating the formers'. Feeding of both oxidized oils without ethoxyquin diets resulted in high rate of death (70%), but in the case with ethoxyquin, it was controlled at the low level (24%). There observed that the lipid contents in the internal organs of fish fed with oxidized oils containing no ehtoxyquin were higher than that of feeding same oils with ethoxyquin and oxidized lipid appeared in the formers', but not detected in the latters'.