Simultaneous determination of ascorbyl palmitate and nine phenolic antioxidants in vegetable oils and edible fats by HPLC

This study describes an HPLC method for the simultaneous determination of ascorbyl palmitate (AP) and synthetic phenolic antioxidants (SPA) in vegetable oils and edible fats in a single run. To achieve this, citric acid was used in combination with isoascorbic acid for stabilization of AP in standard and sample solutions and for deactivation of oxidizing agents in the HPLC system. SPA and AP were directly extracted from samples with methanol containing 1 mg/mL each of citric acid and isoascorbic acid. HPLC analytical and guard columns were pretreated with 90% methanol/acetonitrile 1∶1 (vol/vol), containing 4 mg/mL each of citric acid and isoascorbic acid, and 10% water at pH 3, for 30 min. Under these conditions, AP was stable for about 7 h at room temperature. The relative SD of repeatability for AP (0.5–3.6%) was comparable to that for SPA (0.3–2.8%). Average recovery from spiked samples was 100% for AP, 98–103% for SPA, and 85% for BHT (up to 90% using double extraction with methanol).     

油脂催化加氢催化剂的研究进展

介绍了国内外油脂加氢催化剂的研究状况及金属镍的催化原理、影响催化剂活性的因素、催化剂载体、催化剂中毒、催化剂制备方法、催化反应条件的控制等，指出开展油脂加氢催化剂研究的重要意义。     

油脂市场回顾及未来走势

回顾了2009年的油脂市场,同时,对2010年的国内外油脂市场的油脂作物的产量、油脂产品的消费和库存等方面进行了分析。指出了2010年度影响油脂市场的因素。最后,展望了未来油脂市场的发展趋势。     

Flow and crystallization of saturated fatty acid methyl esters and their binary mixtures

Demand for biodiesel has increased due to being a more environmentally-friendly fuel. Cold weather operation of biodiesel is challenging due to fatty acid methyl ester (FAME) content in biodiesel. Saturated FAMEs crystallize at relatively high temperatures, increase the viscosity of biodiesel, and can clog fuel lines. Here, several factors altered crystallization temperature (CT) of FAMEs, including composition, shear rate, and cooling rate. The crystallization of pure and binary mixtures of methyl palmitate, methyl myristate, and methyl stearate were studied under shear flow and static conditions. Static phase CTs of pure methyl palmitate, methyl myristate, and methyl stearate were 26, 14, and 35°C, respectively. In binary mixtures, CTs were depressed up to 7°C, which agreed with freezing point depression theory. Increasing shear rate up to 100 s⁻¹ decreased CT by 2°C compared to static conditions. Decreasing cooling rate from 1 to 0.1°C/min increased CT less than 2°C. Overall, FAME composition altered CT more than shear flow or cooling rate for pure and binary mixtures of three FAMEs.     

Effect of different cell disruption methods on lipid yield of Schizochytrium sp.

In this study, it was investigated to increase the lipid yield of the microalgae Schizochytrium sp., by applying different cell disruption methods; acid treatment with HCl, osmotic shock, enzyme applications and ultrasonic homogenizer were combined with the Bligh and Dyer or Soxhlet methods. In the Soxhlet method, the lipid and fatty acid yields decreased due to the inability of the method to break down the lipid cells sufficiently and the high temperature application. Enzyme application (hemicellulase treatment at 55°C for 2 days) prior to Bligh and Dyer method (BDE) was found more efficient in terms of lipid and DHA yield compared to other methods. BDE process increased the lipid yield to 21.72 ± 0.74% and DHA content to 19.25 ± 0.09% from lipid yield of 18.87 ± 0.4% and DHA content of 18.41 ± 0.20% by the Bligh and Dyer control (BDC). Major saturated fatty acids were 14:0, 16:0, 18:0, 24:0 and the highest saturated fatty acid was 16:0 (palmitic acid). Lipid health indices such as n-6/n-3, PUFA/SFA, atherogenicity index, thrombogenicity index and hypocholesterolemic/hypercholesterolemic ratios were almost favorable. With this study, appropriate lipid extraction methods were studied to provide an economical and environmental friendly suggestion for future studies to be used in areas such as food, feed and cosmetics grade. It was concluded that the most convenient method among the cell disruption methods was BDE owing to lipid and fatty acid yield.     

Oily Grime Formed on Hard Surfaces of Kitchen Appliances: Chemical Composition and Oxidation Mechanism

The cooking of oil-containing food products at high temperatures results in an insoluble, unsightly, greasy layer of grime on appliance surfaces in residential and commercial kitchens. Over time, adsorbed grime becomes difficult to remove using normal dishwashing detergents. A number of studies have focused on the deterioration and oxidation of oils and the harmful effects that volatile compounds associated with such processes have on human health. Little attention, however, has been paid to kitchen grime. The present study examined grime obtained from the surfaces of appliances such as sirocco fans, filters, and range hoods in residential kitchens in Tokyo. The grime was characterized by X-ray fluorescence spectroscopy (XRF), Fourier-transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), thermal hydrolysis methylation–gas chromatography–mass spectroscopy (THM–GCMS), and nuclear magnetic resonance (NMR) techniques. The chemical composition and structure of the grime differed from those of the edible oils. The grime consisted mainly of polymerized and oxidized triacylglycerols. Bridging between unsaturated acyl groups of triglycerols occurred through thermal oxidation and aging in air, yielding their dimers, trimers, and highly polymerized products while also transforming unsaturated acyl groups into saturated ones. Cross-linking reactions involving dibasic acids also caused polymerization. Those polymerized products strongly adhered to the hard surfaces of the appliances. Small amounts of cellulose fibers from air or towel may also play a role in mechanically stabilizing the dirt structure.

还原条件对镍/氧化铝油脂加氢催化剂的影响研究

采用沉淀法制备了镍/氧化铝催化剂前驱体,前驱体经焙烧、还原、包油成型制得镍/氧化铝油脂加氢催化剂。通过对催化剂进行TPR、氮吸附测定以及棕榈油加氢评价实验,考察了还原条件（还原温度、还原时间和氢气流速等）对催化剂孔结构和加氢活性的影响。结果表明,还原温度对催化剂孔结构和加氢活性影响最明显;催化剂前驱体最适宜的还原条件为还原温度500 ℃、还原时间3.0 h、氢气流速150 mL/min。在此条件下制备的催化剂用于棕榈油加氢反应,能够使每100 g棕榈油碘值由56.0 g降到0.81 g。     

废餐饮油制备生物柴油研究现状与应用前景

介绍了利用废餐饮油制备生物柴油的研究现状与应用前景;叙述了酸催化、碱催化和酶催化的酯交换制备生物柴油工艺,以及每种工艺的优缺点.阐述了我国利用餐饮废油制取生物柴油的意义和利用餐饮废油制取生物柴油的商业化生产的可行性.     

Synthesis of nanoparticle‐immobilized antioxidants and their antioxidative performances in polymer matrices: a review

Antioxidants are used to improve the thermo‐oxidative stability of polymers during processing and to prolong the service life of polymer materials. Immobilizing antioxidants onto nanoparticles is one of the approaches for reducing their physical losses. Research on the design, synthesis and application of nanoparticle‐immobilized antioxidants is reviewed in this article. These kinds of ‘nano‐antioxidants’ reveal good resistance against extraction and show good antioxidative efficiency during long‐term thermal aging, and therefore will have great potential in practical use for improving the stability of polymer materials. © 2018 Society of Chemical Industry     

Effects of oil type on products obtained by cracking of oils and fats

This paper deals with cracking of vegetable oils and animals fats in the presence of zeolite catalysts, the objective being preparation of liquid products similar in their properties to fossil diesel. The effects of oil/fat type on the liquid condensate yields and parameters were monitored. The tests were carried out with rapeseed, sunflower, soybean and jatropha oils as well as with used frying oils. Liquid condensates with yields of 85 to 90% relative to the input oil were obtained at temperatures of 350 to 440 °C applied for the period of 20 to 30 min in the presence of zeolite catalysts NaY and clinoptilolite. The input oil types had no significant effect on the yields and characteristics of the treated condensate. In this respect, used frying oils (UFO) as a feed material match other types of fresh oils and fats. Treated condensates blended with fossil diesel (5-7% of the condensate by volume) are compliant with the EN 590 standard and can thus be used as a component of diesel fuels.     

钢铁常温氧化着色工艺的研究

研究了钢铁常温氧化着色配方及各影响因素,确定了一组以CuSO4、Na2S2O3、NiCl2、Na2SO3为主要组分,可获得最佳氧化着色处理效果的配方,并探讨了可能的成膜机理。实验结果表明该配方着色膜层性能好,通过改变配方中的关键组分,可精确调整氧化膜的颜色,处理工艺简单,对环境污染小。     

Analysis of acrylamide and mechanisms of its formation in deep‐fried products

A reliable and sensitive gas chromatography‐mass spectrometry method was developed for the determination of acrylamide, a toxic compound recently discovered in baked, fried or grilled food. Satisfactory results for repeatability and recoveries were obtained by this method. The limit of detection for acrylamide was 15 μg/kg food and recoveries were between 95 to 103%. The improved method was then employed to study the influence of heat, heating time and type of frying oil on the formation of acrylamide during the deep frying of French fries. In this matrix acrylamide formation was promoted by heating in a time‐dependent manner. It appeared that acrylamide arose, when reducing sugars, dimethylpolysiloxane or partial glycerides were present. Three mechanisms of formation are discussed in this context. Although the mechanistic complexity increases dramatically in the presence of various food components, some recommendations can be given to minimize acrylamide levels in deep fried products.     

国内油脂加氢催化剂的研究现状及发展趋势

介绍了国内油脂加氢催化剂的研究现状,综述了一些催化剂的制备方法和在油脂加氢方面的应用,指出超细及非晶态催化剂是油脂氢化催化剂的发展趋势。     

废弃食用油脂运用活性凹凸棒土脱色的试验研究

因为废弃食用油脂直接采用超临界法制备生物柴油的外观品质很差,所以本文选用活性凹凸棒土对废弃食用油脂进行预处理脱色研究,对影响废弃食用油脂脱色率的因素进行了讨论。得出活性凹凸棒土对废弃食用油脂脱色的最佳条件:活性凹凸棒土质量分数15%,初始脱色温度60℃,终止脱色温度110℃,脱色时间20m in,凹凸棒土投放次数为1次,搅拌速度350 r/m in。     

Storage stability and corrosion studies of renewable raw materials and petrol mixtures: A key issue for their co-processing in refinery units

Mixtures of renewable raw materials such as vegetable oils (crude palm and soybean oil and waste cooking oil) and animal fat unfit for human consumption with petrol feedstock were assessed for considering their co-processing in refinery units. Vacuum gasoil, hydrotreated vacuum gasoil and atmospheric residue were taken as petrol feedstocks. Ageing of these mixtures under storage conditions has been deeply studied. Significant changes in physical properties such as density, viscosity and acidity may promote some problems in the processability in the FCC unit. Moreover, potential polymers formed under storage conditions could lead to the deposit of gums in the tubes of the heat exchangers and the transfer lines previous to the FCC unit. Storage stability studies were performed by means of an accelerated oxidation process according to the UOP 174-84 method. Physical properties including density, viscosity and acidity were measured before and after oxidation treatment. In addition, distillation curve of the mixtures before and after treatment was determined by means of simulated gas chromatography (ASTM D-2887). Physical properties as well as distillation curve of samples were statistically unchanged after oxidation treatment. Likewise, presence of water in the raw feedstock and sediment content in the samples after thermal treatment were not evidenced. Hence, according to the UOP 174-84 method, the different mixtures under study can be considered stable in storage at 77 °C for periods of at least 180 days. Corrosion studies were also carried out to elucidate if the presence of free fatty acids in vegetable oils and animal fats might cause problems in storage systems of refinery units. The assays were performed following the UOP 174-84 method slightly modified by the presence of a carbon metal probe ASTM A 293 Gr C. The leaching of metallic species was monitored after thermal treatment. The results showed a negligible leaching of metallic species for pure petrol feedstock samples as well as for their mixtures with renewable materials.     

Determination of seventeen elements in edible oils and margarine by instrumental neutron activation analysis

Instrumental neutron activation analysis was used to determine the concentration of As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hg, K, Na, Rb, Sb, Sc, Se, Sr and Zn in almond, sunflower, peanut, sesame, linseed, soy, corn and olive oils, as well as in three margarine brands. The concentration of As, Ba, Ce, Cs, Eu, Hg, Rb, Se and Sr were below the system detection limit under the experiment conditions. Chromium was detected only in one of the margarine samples (171 μg/g); Sb only in corn oil (18 ng/g) and Sc only in linseed oil (19 ng/g). Cobalt, Fe, K, Na and Zn were detected in all oil and margarine samples investigated. The concentration ranges for Co, Fe, K, Na and Zn in oils were: 0.016–0.053; 4.45–19.1; 5.93–47.2; 2.44–12.9 and 0.48–1.54 μg/g, respectively. For margarine, the concentration ranges for Co, Fe, K, Na and Zn were 0.09–0.012; 4.53–10.6; 58.3–1140; 13.2–9870 and 0.38–0.47 μg/g, respectively. The elemental contents of the analyzed samples are within the ranges reported in the literature for edible oils and fats.     

Study on the extraction of dyes into a room‐temperature ionic liquid and their mechanisms

The investigation of liquid–liquid extraction of dyes is carried out by using ionic liquid—1‐butyl‐3‐methylimidazolium hexafluorophosphate ([BMIM][PF₆])—as extraction phase. The effects of its process parameters are studied in detail, such as extraction phase ratio, pH of the aqueous phase, and concentration of dicyclohexyl‐18‐crown‐6 (DCH‐18C6) in the organic phase. Important results are obtained as follows: acid dyes can be extracted with [BMIM][PF₆] quantitatively; the removal of reactive dyes is low; however, it can be greatly increased by the addition of DCH‐18C6. The pH value has a great impact on the removal of the acid dye and the reactive dye. However, it does not influence the extraction of the weak acid dye. It is found that the extraction process of acid dyes adopts the form of anion exchange and the soluble part of the ionic liquid plays an important role as counter‐ions. Copyright © 2007 Society of Chemical Industry     

Effectiveness of antioxidants on lipid oxidation and lipid hydrolysis of cod liver oil

The capacity of the natural antioxidant from barley husks to retard oxidation of PUFA in cod liver oil (Gadus morhua) was investigated and compared to synthetic antioxidants. The results confirm the efficacy of a natural antioxidant derived from barley husks to slow down the progress of lipid hydrolysis and increase oxidative stability in cod liver oil. The rates of lipid hydrolysis and lipid oxidation were slowed down with increasing concentration of natural antioxidant used. Using 100 mg of the natural antioxidant was more effective than some synthetic antioxidants (BHA 200 mg and BHT 200 mg) against primary and secondary oxidation. The use of propyl gallate (PG) as an antioxidant (200 mg/kg in cod liver oil) was the most effective antioxidant employed in reducing the production of primary and delaying secondary oxidation products. The formation of free fatty acids (FFA) was significantly lower in samples with natural antioxidant (BE200 and BE100) than in the control samples. BHA and BHT were the most effective antioxidants employed to delay the lipid hydrolysis. Practical applications: The use of barley husks, which are residues of the brewing process, was optimized to obtain a crude antioxidant extract. Natural extracts of phenolic compounds with high antioxidant activity were obtained after prehydrolysis and delignification of barley husks. The raw extracts show more than two‐fold antioxidant capacity compared to BHT in terms of EC50. The results demonstrate the efficacy of a natural antioxidant derived from barley husks. The extract could be used in fatty foods (such as butter, oil, etc.) to prevent rancidity.