Effect of randomization on the oxidative stability of corn oil

Randomized corn oil TAG oxidized much faster than natural oil, but after purification with alumina, they oxidized at the same rate. We showed that this effect could not be attributed to a difference, in total tocopherols in the randomized and natural oils. Polar material recovered from the alumina treatment was fractionated by TLC, and a pro-oxidant effect was found in the fractions containing MAG and DAG. However, MAG and DAG, although mild pro-oxidant could not account for the pro-oxidant effect generated by randomization. No other compounds could be detected in the MAG fraction by MS. The pro-oxidant effect of randomized oil disappeared when EDTA or citric acid was added in sufficient amounts. The pro-oxidant effect of randomized corn oil was increased by the incorporation of additional copper or iron at a concentration that did not catalyze oxidation of the purified oil. Treatment of corn oil with ascorbic acid, ascorbyl-6-palmitate, ethyl acetoacetate, ethyl diacetoacetate, and acetylacetone did not reproduce the effect of the unknown pro-oxidant. Although the identity of the pro-oxidant is still unknown, we have confirmed that it is produced during randomization; it does not have pro-oxidant activity alone, but it facilitates the catalytic activity of the transition metal ions.     

Distribution System Protection with Decentralized Generation Introduced into the System

Cogeneration from renewable energy sources has been universally proposed as a partial alternative to the solution of our nation's energy problems. New technical, safety, and operational problems are introduced when this generation is placed into a distribution grid. Addressed is the problem of distribution system protection with the introduction of cogeneration sources and the changes and modifications which may be required in the application of present-day protection devices. A sample system is considered, and system protection and coordination with and without cogeneration has been calculated through a digital fault and system protection coordination program. The results indicate through the study of several systems that additional coordination and protection considerations will be required when sizable cogeneration sources are introduced to maintain a high degree of reliability and service continuity.     

Influence of Polydimethylsiloxane on the Oxygen Concentration of Oils at Various Temperatures

The effect of temperature on the oil oxygen concentration, tested in both soybean and olive oils with no added polydimethylsiloxane (PDMS), showed that the oxygen concentration increased with temperature to approximately 100 °C. Above 100 °C, the oxygen concentration abruptly decreased. This change was attributed to the balance between the rates of oxygen uptake and consumption by oil oxidation, which favored oxygen consumption over uptake at temperatures above 100 °C. The addition of 100 ppb PDMS to soybean oil, enough to form a continuous layer over the surface of the oil, reduced the oxygen concentration when compared to a soybean oil control containing no added PDMS at temperatures ranging from 93 to 180 °C; thus suggesting an oxygen barrier effect of PDMS. The accumulation of PDMS at the air–oil interface in soybean oil held at 180 °C was determined by comparing the oil’s internal temperature and the apparent surface temperature. A decrease in the apparent surface temperature while the oil was held at a constant internal temperature was attributed to a change in the emissivity of the surface as a consequence of the accumulation of PDMS in the air–oil interface. The presence of PDMS at the air–oil interface was confirmed for 100 ppm of PDMS, a concentration greater than the concentration necessary to form a monolayer of PDMS on the oil surface.     

Abilities of some antioxidants to stabilize soybean oil in industrial use conditions

Antioxidants, chelators, and alcohols were screened at 0.01 and 1.28% by weight for their ability to delay viscosity increase in soybean oil in the presence of metallic colloidal copper and iron at 105°C with air flowing through the sample. Most substances did not significantly enhance the effect of the natural tocopherols in the soybean oil at 0.01%. A few substances were mildly prooxidant, and a few delayed the increase in viscosity significantly. TBHQ at 0.01% was the best antioxidant of those tested. At 1.28% ascorbyl palmitate, BHT, hydroquinone, and TBHQ increased the stability significantly. Again, TBHQ was the most effective. As measured by viscosity increase to 150 CP, TBHQ increased stability about five times over that of soybean oil controls.     

Toluenesulfonate-acyl esters of ethylene glycol and other 1,2-diols as industrial antioxidants with cupric ion

Ethylene glycol esters of soybean oil FA increased in viscosity much more slowly than methyl or glycerol esters when oxidized at 105°C in the presence of flowing air and colloidal copper. This increased stability was caused by a minor constituent of the ethylene glycol esters, which was shown by MS to be a mixed ethanediol fatty acylate p-toluenesulfonate (EFAT). The p-toluenesulfonate group came from the catalyst used in the formation of the ethylene glycol esters. EFAT was quantified by UV spectrometry, HPLC, or GC of the acyl group that it contains. EFAT could be synthesized in good yield by reacting ethylene glycol, a FA, and p-toluenesulfonic acid (TSA) in a 1∶1∶1 molar ratio using a benzene azeotrope to remove water of esterification. EFAT increased the time required for the polymerization of soybean oil by about 27 times but required concentrations of 2–5% by weight. EFAT made with a variety of FA were active in delaying viscosity increase. Ethyl and decyl p-toluenesulfonate were inactive. Replacing ethylene glycol by glycerol and 1,2-propylene glycol but not by 1,3-propylene glycol resulted in active EFAT. TSA itself delayed the polymerization of soybean oil, especially in the presence of free ethylene glycol and FA, but this probably was caused by formation of EFAT during the oxidation test. Colloidal copper could be replaced by cupric ion. EFAT-copper appeared to act as an antioxidant by destroying hydroperoxides without initiation of free radical chains.     

Neutral and polar lipid phase transition of soybeans with various saturated fatty acid contents

Soybeans with modified saturated fatty acid compositions sometimes have lower seed germination rate or other undesirable agronomic traits. To determine if seed germination could be related to the melting transitions of their lipids, triacylglycerols (TAG) and phospholipids (PL) from soybeans with a wide range of saturated fatty acid compositions were examined by differential scanning calorimetry. The melting transition temperatures of both TAG and PL increased with increasing palmitate and stearate percentages. The mean melting points of the various lipids calculated on the basis of the melting points of their fatty acids correlated with the observed transition temperatures. Increased lipid saturation and elevated phase transition temperatures may have contributed to the reduced germination and seedling growth rates of these modified seeds.     

Factors affecting the electrical resistivity of soybean oil methyl ester

Factors affecting the electrical resistivity of soybean oil methyl ester (which is important in some industrial applications) were investigated by the addition of polar constituents [free fatty acids (FFA), water, phospholipids, monoglyceride, sterol, tocopherol, peroxides, and β-carotene] to aluminapurified soybean oil methyl ester (APSBOMe). Investigation of measuring conditions showed that reproducible results were obtained when the potential was greater than 25 V, and the charging time was greater than 10 s. The resistivity of APSBOMe increased logarithmically as temperature decreased linearly. FFA had little effect on resistivity. Saturation with water lowered the resistivity of APSBOMe much more than that of alumina-purified soybean oil (APSBO). Phospholipids reduced the resistivity significantly when added to dry ester, but the addition of water affected the resistivity of the samples containing phospholipids only slightly. Monoglyceride, sterol, tocopherol, and hydroperoxide affected the resistivity of dry methyl ester similarly, but only monoglyceride showed a significant synergistic effect with water. Diacylperoxide and β-carotene had little effect on the resistivity of the ester.     

Production and characterization of a swiss cheese-like product from modified vegetable oils

Seven types of Swiss cheese-like products were made by recombining skim milk with various fat sources: higholeic sunflower oil (HOSO), milk fat, randomized milk fat, HOSO with commerical short-chain fatty acids (C₄−C₁₀) (SCFA) interesterified at 100 and 120% of the levels in the milk fat, HOSO with interesterified milk fat SCFA, and HOSO with dissolved free SCFA. Sensory, chemical, and physical analyses were conducted to evaluate the flavor and texture of the cheeses. All cheeses made from HOSO with interesterified SCFA were not significantly different from milk fat controls in typical Swiss flavor and volatile flavor. HOSO with interesterified SCFA scored significantly higher in these flavors than unmodified HOSO. Swiss flavor was positively correlated with sweetness (0.805), volatile flavor (0.737), caramelized flavor (0.703), non-fat solids (0.663), and SCFA (0.639), and negatively correlated with fat (−0.645) and salt (−0.482) content. A linear regression model was established for typical Swiss flavor that included fat, salt, titratable acidity, and medium- and long-chain fatty acids as variables (R ²=0.91). Instrumental texture profile analysis indicated no differences among the treatments in texture atributes except cohesiveness. The production of a good-flavored Swiss cheeselike product from HOSO with interesterified SCFA appears to be commercially feasible.     

Droplet size and viscosity of tackifier emulsions formed via phase inversion

Tackifier dispersions used in pressure‐sensitive adhesives are made by phase inverting an aqueous rosin ester emulsion. The recipe also includes rosin acid and potassium hydroxide which react to form a surfactant. The amount of surfactant available plays a key role in determining dispersion properties. As the surfactant concentration increases, the point of phase inversion is delayed to larger dispersed phase concentrations. This also results in excess dispersant in the liquid phase and a narrower particle size distribution, even though the droplet size remains relatively unchanged.     

Fractionation of soybean phospholipids by high-performance liquid chromatography with an evaporative light-scattering detector

Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) from 23 soybean lines with a wide range of fatty acid compositions were resolved into seven fractions by high-performance liquid chromatography (HPLC). Fraction identities were assigned from fatty acid compositions determined by gas chromatography (GC). A mass detector, i.e., an evaporative light-scattering detector, was used for HPLC quantification. The detector response was a power function of PC and PE concentrations. Various correction methods were applied to the detector response to obtain the best agreement between phospholipid (PL) fatty acid compositions determined by GC and that calculated from the corrected HPLC fraction percentages. The corrected HPLC fraction composition also was compared with that calculated from stereospecific distribution data using a 1-random-2-random hypothesis. Correlation between PL-fatty acid and HPLC-fraction percentages showed that genetic modification of soybean oil composition caused changes in PL species, which alter physical properties and may alter the physiological functions of PL in biomembranes.