Various properties of microcapsules are described in this part. They include permeability to solutes, mechanical properties and electrical properties. Interactions with a variety of substances are also discussed.
High-oleic safflower oil was heated at 180°C while spraying water in the atmosphere at four levels of oxgen concentration (2,4,10,20%) modified with nitrogen gas to assess the effects of atmospheric oxygen levels on the oxidative deterioration of deep-frying oils. Acid value, carbonyl value, polar material, linoleic acid and tocopherol content, and oxidative stability were measured to evaluate the qiality of heated oils. In general, all these indices correlated with both heating time and the atmospheric oxygen concentration. The increase in acid and carbonyl values and polar material content, and the decrease in linoleic acid and tocopherols in heated oils were almost proportional to the atmospheric oxygen concentration. Compared with heating without water as reported previously, spraying water accelerated the oxidative deterioration of heated oils in all indices. The acid value in particular changed remarkably, but hydrolysis of triacylglycerols did not occur without oxidation. The increase in the acid value was suggested to be due tu thermal oxidation rather than to simple hydrolysis of triacylglycerols. The oxidative stability of the heated oil at 2% and 4% O2 was well maintained. These results suggested that the rate of oxidative deterioration in deep-frying oil is nearly proportional to the atmospheric oxygen concentration.
Cotelomers of acryric acid and n -octyl acrylate, 2-ethylhexyl acrylate or 2-phenylethyl acrylate with same carbon numbers (abbreviation by 2.1NoA-1.2AA, 1.9EhA-2.9AA and 1.6PeA-3.0AA, respectively; 2.1, 1.9 and 1.6 mean number of hydrophobic functions, 1.2, 2.9 and 3.0 mean number of carboxylate functions) were prepared by the radical cotelomerization in presence of 2-aminoethanethiol hydrochloride and examined for surface activity. Critical micelle concentrations (cmcs) of 2.1NoA-1.2AA, and 1.9EhA-2.9AA were 1/16 and 1/5 of that of conventional surfactant of sodium n -octanoate. Surface tensions of aqueous solutions of 2.1NoA-1.2AA, 1.9EhA-2.9AA and 1.6PeA-3.0AA were 32.3, 27.3 and 41.1 mN m-1 at each cmc, respectively. 2.1NoA-1.2AA having straight alkyl chains and 1.9EhA-2.9AA having branched alkyl chains gave figh foaming abilities in water as well as in hard water. 2.1NoA-1.2AA had high foam stability, while 1.9EhA-2.9AA showed poor stability. The highly stable oil-in-water type emulsions, which were brought about by shaking toluene with aqueous solutions of cotelomers, were formed by using 1.6PeA-3.0AA having aromatic nucleus. Interfacial tensions between aqueous solutions of 2.1NoA-1.2AA, 1.9EhA-2.9AA and 1.6PeA-3.0AA and toluene were 4, 8 and 1mN m-1, respectively.
7-Ketocholesterol (7C=O), one of free radical-mediated cholesterol oxidation products, has received much attention owing to its biologically active functions and potential contributions to various pathological situations. 7-Ketocholesterol (7C=O) is a one-electron reduced form of cholesterol 7-hydroperoxide (7-OOH) and possibly may be formed as a secondary product via 7-OOH, but the mechanism of 7C=O generation is not well understood. The large generation of 7C=O in cholesterol oxidation has been observed in the present study with azo radical initiator, AAPH and large unilamellar vesicles (LUVs) consisting of saturated or unsaturated phosphatidylcholine. The study has been thus made to determine the mechanism of formation by means of this oxidation system. Large formation of 7-oxygenated products, particularly 7C=O has been demonstrated with GC, GC/MS, TLC and HPLC. A time course study of these products has indicated the generation rates of 7C=O to be far higher than those of 7-OOH in saturated and unsaturated LUVs. Unsaturated phosphatidylcholine present in cholesterol oxidation has resulted in greater formation of 7-hydroxycholesterol (7-OH) and cholesterol 5,6-epoxide (EP) without affecting 7-OOH formation. The generation mechanism of 7C=O has been investigated with the antioxidants Ebselen, which reduces lipid hydroperoxide to the corresponding alcohol, and 2-keto-4-thiolmethyl butyric acid (KTBA), an alkoxyl radical scavenger. KTBA completely inhibited the formation of 7C=O, accompanied by the complete suppression of cholesterol oxidation in saturated LUV and over 95% suppression in unsaturated LUV. Ebselen had little effect on 7C=O formation in either LUV but had an effect on that of 7-OH. 7-Ketocholesterol (7C=O) formation would therefore appear to occur directly from cholesterol 7-alkoxyl radical by a route different from the decomposition of 7-OOH. The generation mechanism proposed for 7C=O is as follows; 1) cholesterol 7-alkoxyl radical formation by dyad termination reaction with the cholesterol 7-peroxyl radical, and 2) 7-ketocholesterol formation through β-scisson reaction of cholesterol 7-alkoxyl radical via an aldehyde intermediate.
The thermoal oxidation rete of oil at 180°C was previously found proprtional to atmospheric oxygen in contrast to autoxidation of fats and oils at room temperature that could be retarded under an atmosphere containing less than 1% oxygen. Chicken nughetts were deepfried in high-oleic safflower oil and soybean under 2% or 20% oxygen and the quality of the frying oil and flavor of the nughetts were assessed periodically. Based on acid and carbonyl values, content of polar compounds and other parameters, deterioration of deep-frying oil was efficiently retarded by frying under 2% oxygen. When residual tocopherol levels in the frying oil decreased to less than 10mg/100g (high-oleic safflower oil), 60mg/100g (soybean oil), oxidative deterioration was extensive. Foods deep-fried of low oxygen showed significantly better quality at 40h in soybean oil and 10h in high-oleic safflower oil, compared with the control. Lessening oxygen concentration by replacement with nitrogen gas would thus appear to improve the stability of deep-frying oil and of fried food quality.
Examination was made of the effects of a conjugated linoleic acid (CLA) on body weight gain and abdominal fat accumulation of ovariectomized mice for comparison with those of three dietary oils. Mice were fed seven weeks one of four deits containing 5% corn oil (CO), 0.5% Tonalin (68% CLA) and 4.5% corn oil, 5% linseed oil (LO) or 5% fish oil (FO). Amounts of food consumed were not significantly different among these groups. A body weight of the CLA-fed group was less than that of the LO- fed group (P<0.05), and its abdominal fat pad weight (% body weight), below that of the CO- or LO- groups (p<0.01, p<0.001) while essentially the same as for the FO group. Plasma glucose of the CLA-group exceeded that of the other three groups (p<0.05). CLA would thus appear to exert potent fat reducing activity which would prevent obesity.
4,4-Dimethyl- and 4-monomethylsterols in seeds of Setaria italica and Echinochloa frumentacea were analyzed by GC-MS. Two 4,4-dimethylsterols and five 4-monomethylsterols were shown present in S. italica seeds, and three 4,4-dimethylsterols and eleven 4-monomethylsterols were found in E. frumentacea seeds.
Margarines and shortenings contain trans fatty acids formed during the hydrogenation of material oils and fats. Trans fatty acids have been shown to influence serum cholesterol and lipoprotein levels subsequent to consumption of these substances in certain amounts. For preparation of margarines for household use, free from trans fatty acids are sold in European markets. For detemination of trans fatty acid content in margarines and baked confectioneries produced in the United States, 41 samples (16 margarines and 25 baked confectioneries) were purchased in Hawaii, December 1998 and trans fatty acid content was compared with that previously determined. Analysis of trans fatty acids was carried out by capillary GLC in conjunction with AgNO3 impregnated thin-layer chromatography. Total trans fatty acid content of cup type margerines averaged 12.1% (0.8-19.5%), being slightly lower than previously reported. Two samples contained less than 1% of total trans fatty acids produced by unhydrogenated oil or diacylglycerol (about 4%) instead ot hydrogenated oil. One margarine sample labeled trans fatty acid free contained trans fatty acids at 11.6%, 0.3g for one serving. Average content of total trans fatty acids of carton type margarines was 23.4% (18.0-27.5%), essentially the same as previously reported. Bottled margarines contained 2.4% total trans fatty acids on average. Average total trans fatty acid content of cookies, crackers and other baked confectionery was 20.8% (8.6-34.1%), 31.7% (12.2-40.5%) and 26.1% (5.2-40.0%), respectively and the corresponding values for 1994 products were, for cookies (n=6), 23.1% and crackers (n=13), 30.4%. Thus, total trans fatty acid content of cookies currently produced is slightly less compared to that in 1994.