Influence of fatty acids on the tocopherol stability in vegetable oils during microwave heating

Effects of 0, 0.05, 0.25, 0.50 and 1.0% levels of fatty acids (caproic, caprylic, capric and lauric) or hydrocarbons (decane and dodecane) on tocopherol stability in vegetable oils during microwave heating were determined by measuring tocopherol losses and carbonyl and anisidine values. The fatty acids showed similar prooxidant activities toward tocopherols in purified vegetable, oils when heated in a microwave oven. However, decane or dodecane, which had the same number of carbons as capric or lauric acid but no carboxylic group, did not show prooxidant activity. The shorter the chainlength and the higher the level of fatty acids, the greater was the reduction of tocopherols in the oils. The addition of low-molecular weight fatty acids resulted in greater acceleration in the oxidation of to pay attention to these free fatty acids produced in the oils when heated in a microwave oven.     

Determination of milk fat in chocolates by gas-liquid chromatography of triglycerides and fatty acids

The combination of two routine methods is proposed to determine the content of milk fat (MF) in chocolates, which is applicable even in the presence of lauric fats or others. The content of MF is obtained from the sum of C₄₀, C₄₂, and C₄₄ medium-chain triglycerides, determined by capillary gas-liquid chromatography (GLC). A new method, based on methyl esters of lauric acid and on minor acids situated between myristic and palmitic, is proposed. It enables detection and estimation of potential lauric fats, as well as the determination of the actual content of MF. The influence of other vegetable and animal fats is discussed. We analyzed 45 MF samples extracted from industrial milk powders and from pure or fractionated MF for chocolate manufacturing or pastry by GLC of triglycerides. We also analyzed by capillary GLC the methyl esters from 22 of those fats. Mixtures of these 22 MF samples with a cocoa butter also were used for chromatographic analyses of methyl esters and triglyceride. Results from the various analytical methods have been presented.     

Kinetics of the catalytic esterification of castor oil with lauric acid using <Emphasis Type="Italic">n</Emphasis>-butyl benzene as a water entrainer

The esterification of castor oil with lauric acid was investigated using tetra n-butyl titanate (TBT), SnCl₂·2H₂O (stannous chloride), CoCl₂·6H₂O (cobalt chloride), and (CH₃COO)₂Zn·2H₂O (zinc acetate dihydrate) as catalysts. Effects of catalyst concentration and reaction temperature on the progress of the reaction were investigated. TBT was the best catalyst for the esterification of castor oil with lauric acid at temperatures lower than 200°C. The reaction was first order with respect to each reactant. The activation energy for the esterification reaction of castor oil with lauric acid using TBT was 26.69 kcal/mol. The rate constants obtained for the esterification of castor oil with decanoic, lauric, palmitic, and stearic acids were nearly the same (15.80, 15.44, 15.06, and 14.67 mL mol⁻¹ min⁻¹), as were the rate constants obtained for the reaction of castor oil and hydrogenated castor oil.     

Liquid laundry detergents based on soap andα-sulfo methyl esters

It is well known that soap is one of the most effective cleaning agents in soft water. However, soap is equally notorious for some of its deficiencies, especially formation of soap scum due to the precipitation of calcium and magnesium soaps in hard water, low solubility in water, poor cleaning in cold water, greying of fabrics and dulling of hard surfaces such as ceramic tiles. Attributes of soap that should not be overlooked, especially in today’s environment, include an abundant and natural raw material supply (vegetable oils and fats) and excellent human and environmental safety profiles that are superior to most synthetic surfactants. Presented in part at an AOCS/CSMA Detergent Industry Conference, Hershey, Pennsylvania, October 31, 1989.     

月桂酸-癸酸二元体系的固-液相平衡特性

介绍了月桂酸-癸酸二元体系相图的特点.用规则溶液模型预测相图中的液相线,分析了液相线方程中分子间相互作用能ue的作用和物理意义.根据月桂酸和癸酸分子的相对大小、结构特点,提出了简化液相线方程的方法,计算了混合物的液相线方程.实验研究月桂酸-癸酸混合物的相变特点,结果表明:月桂酸和癸酸中的杂质对混合物的相变温度有重要影响.     

Fabrication and Properties of Electrospun PAN/LA–SA/TiO2 Composite Phase Change Fiber

A stabilized matrix to accommodate phase change materials is essential in the application and functioning of phase change materials. In this study, lauric–stearic acid eutectics and TiO₂ were doped with polyacrylonitrile solution to electrospin a composite phase change nanofibers. The surface morphology indicated typical nanofibrous structure of polyacrylonitrile/lauric–stearic/TiO₂ composite nanofibers, and the diameter of fiber increased with the increase in lauric–stearic eutectic mass ratio. Differential scanning calorimetry analysis showed the temperature of melting peak of polyacrylonitrile/lauric–stearic/TiO₂ nanofiber was around 25°C, which was lower than that of pure lauric–stearic eutectics. Latent heat value of the composite fibers gradually increased with the increase in lauric–stearic mass ratio. Thermal cycle test and thermogravimetric analysis showed that polyacrylonitrile/lauric–stearic/TiO₂ composite fibers were reversible thermal energy storage materials with good thermal stability below 100°C.     

Evaluation of two antimicrobial packaging films against Escherichia coli O157:H7 strains in vitro and during storage of a Spanish ripened sheep cheese (Zamorano)

The antimicrobial activity of two packaging films (polypropylene – PP- and polyethylene terephthalate – PET-) coated with different concentrations (0, 4, 6 and 8%) of essential oil from Origanum vulgare (OR) and Ethyl Lauroyl Arginate HCl (LAE) was tested against two Escherichia coli O157:H7 strains using in vitro systems and a raw milk sheep cheese model (Zamorano). The influence of the antimicrobials on the sensory attributes of cheese was also evaluated. For both strains, the MBC (minimum bactericidal concentration) values were identical to their respective MIC (minimum inhibitory concentration) values and lower for LAE (25 mg/l) than for OR (200–400 mg/l). PP and PET films coated with OR were tested by a vapour phase assay and the Japanese Standard method (JIS Z 2801:2000). Both films coated with LAE were tested by an agar diffusion method. Overall, in vitro tests were effective against both strains. The inhibitory activity depended on the active compound concentration, the target strain and the packaging material, PET being more effective than PP. For inoculated cheese slices, OR and LAE PP films did not effectively decrease E. coli O157:H7 counts after 7-days cold storage. PET films incorporating 6 and 8% of OR and LAE significantly (p < 0.05) decreased the numbers of both strains and also did 4% for the reference and wild strain depending on the antimicrobial. LAE PP, OR PET and LAE PET did not significantly (p > 0.05) affect sensorial characteristics of Zamorano cheese. Packaging with PET films coated with ≥6% LAE concentrations might be useful in reducing E. coli O157:H7 numbers in sheep cheese.     

珠光型椰油酸二乙醇酰胺合成工艺的研究

以椰油酸为原料,合成了珠光型椰油酸二乙醇酰胺.通过正交试验筛选出珠光型椰油酸二乙醇酰胺最佳合成工艺条件:椰油酸与甲醇摩尔比为1:10,椰油酸与催化剂摩尔比为1:0.06,常温催化反应3h.后在105℃温度下反应2h.珠光剂是一种混合物,珠光光泽的形成与温度有关,光泽的优劣与混合物的比例以及银镜晶体的大小有关.     

Enzymatic esterification of (−)-menthol with lauric acid in isooctane by sorbitan monostearate-coated lipase from Candida rugosa

Esterification of (−)-menthol and (±)-menthol with lauric acid in isooctane was successfully catalyzed by a commercial nonioic surfactant (sorbitan monosterate)-coated lipase from Candida rugosa (Lipase AY “Amano” 30) at the molar ratio of 1∶1 and at 35°C using 1.5 g enzyme/g (−)-menthol and 0.1-g molecular sieves. After 1 h, molar conversion of (−)-menthol reached 81%. Equilibrium was reached after ca. 4 h, giving a (−)-menthol molar conversion of 94%. Under the same conditions, native lipase catalyzed the esterification of (−)-menthol and lauric acid to yield a molar conversion of 93% after 72 h. Coating the lipase with sorbitan monosterate increased the esterification rates of both (−)-menthol and (±)-menthol with lauric acid. After 6 h, the molar conversions of (−)-menthol and (±)-menthol were 94, and 62%, respectively.