Influence of ascorbic acid and ascorbyl palmitate on the aroma composition of an oxidized vegetable oil and its emulsion

The formation of conjugated diene hydroperoxides and hexanal was compared to the development of aroma profiles during initial lipid oxidation of a vegetable oil and its 40% oil-in-water emulsion at 60°C. The aroma profiles of the oil and the emulsion with and without addition of ascorbic acid or ascorbyl palmitate were compared. The aroma compounds were isolated under a model mouth system and analyzed by gas chromatography/sniffing port analysis. Detectable odors were found and corresponded to 11 and 14 volatile compounds in the oil and the emulsion, respectively. The emulsion had higher lipid oxidation rates than the oil. Addition of ascorbic acid and ascorbyl palmitate had little influence on the aroma composition of the oil. In the emulsion, addition of these compounds resulted in diminished generation of odor active compounds. Results of measurements of conjugated diene hydroperoxides and headspace hexanal corresponded to that of the lipid oxidation rate in general, but predicted insufficiently the alterations in the aroma compositions by antioxidants.     

油包水乳化体系的配方设计及生产工艺研究(续前)

论述了影响油包水乳化体系稳定性的因素、油包水的配方设计原则以及油包水的生产工艺的控制和调整,并介绍了有利凯玛公司的油包水乳化剂。     

Analysis of the volatile fraction from sunflower oil extracted under pressure

This study concerns the analysis of volatile components that may contribute to the formation of the flavor of the oil extracted from sunflower seeds. The compounds were trapped on a charcoal cartridge, then desorbed and analyzed by gas chromatography/mass spectrometry. The principal compounds were terpenes (about 225 mg/L) consisting of α-pinene (80%), limonene (5%), sabinene (3.3%), β-pinene (1.8%), 1,2,6,6-tetramethyl-1,3-cyclohexadiene (1.5%), and camphene (1.2%). There were also a small amount of hexanal (1.3%) and traces (<1%) of unidentified compounds, which probably correspond to other terpenic hydrocarbons and to terpenic alcohols and/or aldehydes.     

物理破乳技术在废油处理中的应用

针对目前废油资源化处理中油水乳化液的化学成分及乳状结构的复杂性,常规化学破乳方法成本高、针对性强、易腐蚀设备等问题,综述了外加电场、磁场、离心场等物理破乳技术在废油处理中的应用和研究现状,提出了水击谐波破乳的新方法,丰富了在废油处理中的物理破乳方法。分析了物理破乳方法的发展趋势。     

Lipid oxidation inhibiting capacities of blackseed essential oil and rosemary extract

Lipid oxidation is the main deterioration process that occurs in vegetable oils containing lipid molecules with polyunsaturation. The aim of the present study was to investigate the possible effects of blackseed (Nigella sativa L.) essential oil (BEO) and rosemary (Rosmarinus officinalis L.) extract (RE) on stabilization of sunflower oil under accelerated storage conditions. RE was obtained by soxhlet extraction using methanol, whereas BEO was hydrodistilled from the blackseed extract obtained by extraction using petroleum ether (b.p. 40–60°C). The results indicate that both extracts stabilize sunflower oil to a certain extent, the extent being greater with RE than with BEO based on measurements of peroxide value, p‐anisidine value, amount of nonoxidized linoleic acid in saponified oil samples by HPLC‐DAD, concentration of conjugated diene hydroperoxide, and UV light absorption. The oil stabilizing effect of BEO against lipid oxidation, especially at concentrations of 0.06 and 0.1 g/100 g oil was found to increase as the temperature increased, according to principal component analysis results. Based on its strong lipid oxidation inhibiting capacity, RE can be used as a potential natural extract for stabilizing sunflower oil against oxidation. BEO, at carefully selected concentrations, can be suggested as an alternative supplement of plant origin for improving oil stabilization. Practical applications: Sunflower oil is a widely used vegetable oil for cooking and frying, and has a high linoleic acid content of about 40–70%. Here we show that sunflower oil can be stabilized by adding rosemary and blackseed extracts. The treatment can be useful especially in applications which require heating the oil to high temperatures.     

乳化炸药用油相材料的研究

对一种炼油副产品作为乳化炸药油相材料的可行性进行了研究。该炼油副产品价格低廉,可降低乳化炸药的生产成本。通过对乳化效果、乳化基质稳定性以及敏化效果进行实验发现,此种炼油副产品能取代目前的油相材料制备乳化炸药。将炼油副产品和机械油、微晶蜡复配具有较强的乳化效果,所制备的乳化基质稳定性较好。此外,采用炼油副产品制备的乳化基质可按目前的敏化配方和工艺进行敏化。     

Oxidation of sunflower oil during storage

Effects of temperature and oxygen concentration on oxidative deterioration during storage of crude sunflower oils, obtained by pressing and solvent extraction, were studied. Oxidation was monitored through several analytical and chromatographic methods that determine chemical and physical changes or analyze specific oxidation compounds at different stages of the process: peroxide value, p-anisidine value, free fatty acids, weight gain, total content and distribution of polar compounds, and composition of fatty acids. Extracted oil showed a higher oxidative stability than pressed oil. Oxidative deterioration was strongly dependent on temperature, oxygen availability, and the ratio of exposed surface to sample volume. A kinetic model of two series reactions was developed to represent oxidation rate in terms of peroxide value, the reaction rate constants and their temperature dependence being evaluated by nonlinear regression. Finally, good correlations between the percentage of polar compounds or oxidized triglyceride monomers and the peroxide value were found.     

餐饮油烟中典型VOCs催化氧化研究进展

近年来,餐饮油烟逐渐成为城市大气污染的主要来源之一,油烟中挥发性有机化合物（VOCs）对人体及环境均产生非常大的危害,对其治理刻不容缓。催化燃烧技术因具备去除效率高、无二次污染等优点在有机废气治理方面有着广阔的应用前景。鉴于此,本文首先总结并分析了油烟中典型挥发性有机物的成分,发现油烟中烃类、醛酮类污染物含量较高,其次包括酸酯类、醇类和少量的多环芳烃类污染物。在此基础上,重点综述了催化燃烧技术对净化上述典型挥发性有机污染物的研究进展,并对近年来常用的催化剂包括贵金属催化剂、非贵金属催化剂及特定结构的催化剂进行了归纳和整理。最后结合油烟VOCs成分及其特点,总结了不同种类型的催化剂在油烟治理中的适用性,并对催化燃烧技术在油烟治理方面的研究前景作出了展望。     

超亲水SiO2修饰膜的构建及其油水乳液分离性能

采用硅溶胶和多巴胺作为修饰剂,通过一步反应在微孔聚丙烯膜(MPPM)表面构建了SiO₂修饰层。利用FTIR、ESEM和EDX对膜进行了表征,发现膜表面SiO₂颗粒分布非常均匀。水/油接触角及纯水通量实验结果表明,修饰膜具有超亲水性及水下超疏油性,透水能力强,水通量大[在0.1 MPa时,水通量高达(5100±500)L·m^-2·h^-1]。油水乳液分离结果表明,修饰膜能有效分离油水乳液,在0.05 MPa时,油水乳液水通量达2830 L·m^-2·h^-1,油截留率达99.8%以上,即使过膜压力增大到0.15 MPa,油截留率也能保持在99%以上,且膜表面的油污可用水清洗除去,展现出很好的应用前景。     

DSC determination of thermally oxidized olive oil

The feasibility of using DSC as an analytical method to evaluate the autoxidation of olive oil at 50°C and thermal oxidation at 93 and 180°C in 10-mL airtight vials was studied. DSC peak enthalpy and peak crystallization temperatures were compared with headspace oxygen depletion and headspace volatiles in oxidized oil samples. A single crystallization peak was found in olive oil. The crystallization peak shifted to lower temperatures, and the enthalpy associated with this phase transition decreased as the exposure time increased at 93 and 180°C. DSC peak enthalpy in olive oil at 50, 93, and 180°C showed correlations of 0.84, 0.91, and 0.95, respectively, with headspace oxygen depletion in sample bottles. Correlation of DSC initial peak temperature with headspace oxygen depletion was 0.53, 0.87, and 0.95 at 50, 93, and 180°C, respectively. Correlations of DSC peak enthalpy and initial peak temperature with headspace volatiles at 180°C were 0.95 and 0.97, respectively. These results indicate that DSC is a good analytical method to determine the oxidative stability of olive oil at frying temperature.     

Antioxidant activity of phenolic compounds in sunflower oil‐in‐water emulsions containing sodium caseinate and lactose

The aim of this work was to study the evolution of oxidation and the efficiency of phenolic antioxidants in sunflower oil‐in‐water emulsions containing sodium caseinate and lactose (Cas‐Lac) or stabilized by Tween‐20 (T‐20). Two groups of phenolic antioxidants which are structurally similar were tested, i.e. (1) α‐tocopherol and its water‐soluble analogue, Trolox; and (2) gallic acid and its ester derivatives propyl gallate and dodecyl gallate. Emulsion samples were oxidized at 40 °C and the progress of oxidation was followed through quantitation of oxidized triacylglycerol monomers, dimers and oligomers. Results showed that Cas‐Lac emulsions were more stable to oxidation than T‐20 emulsions. In both types of emulsions, the most protective antioxidants were the compounds of lower polarity, namely, α‐tocopherol and dodecyl gallate. It was also found that substantial amounts of α‐tocopherol coexisted with significant polymerization, which was indicative of the heterogeneity of oxidation, i.e. differences of oxidation rate in oil droplets.     

高粘度硅油乳液的制备研究

高粘度硅油一直存在难乳化及乳液稳定性差的问题。本文以100万cs硅油为原料,成功制得了高粘度硅油乳液,并对影响其稳定性的因素进行了探讨。结果表明:乳化剂的选择及用量、乳化时间、分散剂的选择及用量均影响硅油的乳化及乳液的稳定性。     

Frying performance of a sunflower/palm oil blend in comparison with pure palm oil

The aim of this study was to test the performance of a vegetable oil blend formulated as alternative to pure palm oil as frying medium. For this purpose, the evolution of many analytical parameters (free acidity, spectrophotometric indices, total polar components, fatty acid composition, short‐chain fatty acids, tocopherol and tocotrienol content and composition, color, flavor evaluated by means of an electronic nose) of the selected blend (sunflower/palm oil 65 : 35 vol/vol) has been monitored during a prolonged frying process (8 h discontinuous frying without oil replenishment) in comparison to pure palm oil. Sensory attributes of the fried food were also evaluated. The blend proved to keep qualitative parameters comparable to those shown by palm oil during the prolonged frying process. Even if some oxidation indices, such as spectrophotometric indices, short‐chain fatty acids and total polar components, increased faster in the blend, it showed a higher tocopherol content and a lower increment in free fatty acids as compared to pure palm oil. Chips fried in the two oils did not show significantly different sensory profiles.     

Thermoxidative and hydrolytic changes in sunflower oil used in fryings with a fast turnover of fresh oil

The modification of a sunflower oil used for 75 repeated deep-fat fryings of potatoes, with a fast turnover of fresh oil during frying, was evaluated by measuring the total polar components isolated by column chromatography. The total polar components increased rapidly during the first 20 fryings from 5.09±0.21 (mean±SD) mg/100 mg unused oil to 15.99±0.40, followed by minor but also significant changes until the thirtieth frying (17.99±0.41 mg/100 mg oil). The level did not increase further with continued frying. Further, the polar fraction was examined by high-performance size-exclusion chromatography. Triglyceride polymers increased from 0.10±0.01 mg/100 mg unused oil to 1.65±0.13 and 3.44±0.17 mg/100 mg oil at the twentieth and seventy-fifth fryings, respectively. Triglyceride dimers also increased significantly from 0.75±0.12 mg/100 mg unused oil to 6.25±0.28 (mg/100 mg oil) at the twentieth frying and to 7.09±0.31 mg/100 mg oil at the thirtieth frying, with no further significant changes. Oxidized triglycerides also significantly increased, but at the twentieth frying reached a near-steady state of 6.26 mg/100 mg oil. Diglycerides and free fatty acid levels, related to hydrolytic alteration, did not increase with continued fryings. The results indicate that during deep-fat frying of potatoes with fast turnover of fresh sunflower oil, more thermoxidative than hydrolytic processes take place. A dramatic leap of total polar content and a change of compounds related to thermoxidative alteration of the oil were found during the first twenty fryings, followed by minor changes and by a tendency to reach a near-steady state throughout the successive fryings.     

Poly(methyl methacrylate) multihollow particles by water in oil in water emulsion polymerization

Multihollow‐structured poly(methyl methacrylate) (PMMA) particles were produced employing the water in oil in water (W/O/W) emulsion polymerization technique where sorbitan monooleate was used as a primary surfactant and sodium laurylsulfate and Glucopen, a polypeptide derivative, were used as secondary surfactants. Vinyl acetate was copolymerized to improve the wettability of the particles. The agitation speed and concentration of the urethane acrylate employed as a reactive viscosity enhancer played a crucial role in determining the morphology and average size of the PMMA multihollow particles. In high agitation speed the multihollow particles displayed a small size and narrow size distribution resulting from efficient droplet breakup. Especially when the urethane acrylate was incorporated, PMMA multihollow particles with a smooth and clear surface were achieved. This was believed to be because the urethane acrylate increased the viscosity of the monomer mixture and helped to form the stable W/O/W emulsion droplets that restricted droplet coalescence during polymerization. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 38–44, 2000     

水/油两相萃取系统下利用O2光化学氧化噻吩

引言 汽油或柴油中的含硫化合物如硫醇、硫醚、噻吩、苯并噻吩(BT)和二苯噻吩(BT)燃烧后产生SOX,是酸雨和空气污染的主要来源,并可导致人产生呼吸道疾.