Free primary alcohols in oils and waxes from germs,kernels and other components of nuts,seeds, fruits and cereals

The composition of free primary alcohols in oils and waxes obtained from the germ, kernel, seed coat, shell and skin (peel) of various nuts, seeds, fruits and cereals and from the chrysalis of silkworm was examined. These alcohols are usually present in small amounts, along with large quantities of hydrocarbons, esters and glycerides in oils and waxes. Thus, it is necessary to remove hydrocarbons, esters and glycerides to analyze the alcohols. We found that preparative reverse-phase thin-layer chromatography (TLC) was the best way to isolate alcohols from oils and waxes. Gas liquid chromatography (GLC) then detected hexacosanol, octacosanol and triacontanol in the oils and waxes. Octacosanol usually was the predominant alcohol. Relationships between the organs from nuts, seeds, fruits and cereals and the contents of octacosanol are suggested. For example, degermed kernels contained two times more octacosanol than the germ, and the skin coat and shell contained one-half and one-fortieth the octacosanol of the germ, respectively.     

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.     

Characterization of the TAG of peanut oil by electrospray LC-MS-MS

A study of processed peanut oil was undertaken to assess the utility of HPLC combined with tandem MS to obtain data easily regarding the number of TAG of fats and oils and their FA composition. Mass chromatograms and spectra corresponding to only TAG of a single M.W. were obtained for the full range of TAG in the sample. Analysis of the mass spectra allowed the identification of more than 160 TAG in the sample by their FA composition. In addition, it was possible to estimate relative abundances of the TAG and suggest the position of the FA on glycerol for a limited number of cases. This technique greatly simplifies the task of assigning FA to coeluting TAG and facilitates identification of TAG present in trace quantities in mixtures, with possible application in circumstances where such trace TAG could be significant markers. Results are quickly obtained without extensive sample preparation or prefractionation of the sample.     

Degradation of the oxirane ring of epoxidized vegetable oils with solvated acetic acid using cation‐exchange resins

Vegetable oil epoxides (oxiranes) are customarily manufactured using acetic acid (AA) as oxygen carrier and reactant source, in aqueous/organic media. Further attack of the oxirane ring by AA proceeds in this acid‐catalyzed process, lowering yield. We report a study of the degradation of the ring by water‐solvated AA, using Amberlite IR‐120 as heterogeneous catalyst. The ring opening with solvated AA was found to be first order with respect to the concentration of epoxide groups and second order with respect to the carboxylic acid, with an activation energy of 58.7 ± 0.42 kJ mol^?1. This value is within the range found in liquid‐liquid systems (51.3–66.3 kJ mol^?1). Yet, using IR‐120, the degradation increases identically either by adding more mass of catalyst or by reducing its particle diameter while keeping the total mass constant, as both situations lead to higher external (exposed) area of the acidic catalyst (i.e., free protons associated to the sulfonic group) on the outer surface of the ion exchange resin beads. These free protons, in turn, become available to catalyze the attack on the oxirane groups of the long‐chain fatty acids, which cannot enter (diffuse) into the gel phase of the resin. Despite the unavoidable presence of surface‐exposed protons, the degradation can be reduced by several orders of magnitude – for similar process conditions – by using this type of heterogeneous catalysts instead of mineral acids.     

Classification of vegetable oils by high-resolution <Superscript>13</Superscript>C NMR spectroscopy using chromatographically obtained oil fractions

¹³C NMR spectra of oil fractions obtained chromatographically from 109 vegetable oils were obtained and analyzed to evaluate the potential use of those fractions in the classification of vegetable oils and to compare the results with the NMR analysis of complete oils. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north Africa; “lampante” olive, refined olive, refined olive pomace, hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed, soybean, and sunflower oils; and mixtures of virgin olive oils from different geographical origins. Oils were divided into two sets of samples. The training set (98 samples) was employed to select the variables that resulted in significant discrimination among the different oil classes. By using stepwise discriminant analysis, more than 98% of correct validated assignments were obtained; these results were confirmed when applied to the test set (11 blind samples). Results suggest that the use of oil fractions considerably increases the discriminating power of NMR in the analysis of vegetable oils.     

Oxidative stability of soybean oils with altered fatty acid compositions

The oxidative stabilities of one canola oil and six soybean oils of various fatty acid compositions were compared in terms of peroxide values, conjugated dienoic acid values and sensory evaluations. Two of the soybean oils (Hardin and BSR 101) were from common commercial varieties. The other four soybean oils were from experimental lines developed in a mutation breeding program at Iowa State University that included A17 with 1.5% linolenate and 15.2% palmitate; A16 with 2% linolenate and 10.8% palmitate; A87-191039 with 2% linolenate and 29.6% oleate; and A6 with 27.5% stearate. Seed from the soybean genotypes was cold pressed. Crude canola oil was obtained without additives. All oils were refined, bleached and deodorized under laboratory conditions with no additives and stored at 60°C for 15 days. The A17, A16, A87-191039 and A6 oils were generally more stable to oxidation than the commercial soybean varieties and canola oil as evaluated by chemical and sensory tests. Canola oil was much less stable than Hardin and BSR 101 oils by both chemical and sensory tests. The peroxide values and flavor scores of oils were highly correlated with the initial amounts of linolenate (r=0.95, P=0.001). Flavor quality and flavor intensity had negative correlations with linolenate, (r=−0.89, P=0.007) and (r=−0.86, P=0.013), respectively.     

Fatty acid composition of spanish shortenings with special emphasis on <Emphasis Type="Italic">trans</Emphasis> unsaturation content as determined by fourier transform infrared spectroscopy and gas chromatography

A Fourier transform infrared spectroscopic procedure was used to analyze 34 edible fats (22 shortenings and 12 vegetable margarines) as neat fats (IR_NF) to determine their total trans fatty acid (TFA) content. The sloping baseline was corrected with a reference spectrum based on a nonprocessed olive oil. The calibration was done using seven partially hydrogenated fats with an individual TFA content previously determined by the combination of gas chromatography (GC) with argentation thin-layer chromatography. Taking into account the different absorptivities of various trans isomers, different correction factors were calculated using the calibration standards (0.83 and 1.71 for single trans bonds in both diethylene and triethylene and for trans, trans-diethylene fatty acids, respectively) and applied to calculate the total TFA of samples. Moreover, the samples were converted to their methyl esters and reanalyzed following the same procedure (IR_FAME). Differences in TFA content of fats were not found when a t-test was used to compare the results obtained by IR_NF vs. either IR_FAME or GC, suggesting that IR of neat fats could be used, thus avoiding the need to prepare sample solutions in organic solvents and to prepare fatty acid methyl esters. The mean TFA content (determined by IR_NF) of a representative group of Spanish shortenings (22 samples) that varied widely in terms of fat sources, processes, and purposes (bakery, sandwiches, ice cream, coatings, chocolate coverings) was 6.55±11.40%, although more than 54% contained <3% of TFA. Fatty acid composition of shortenings by direct GC using a 100-m polar cyanopolysiloxane capillary column indicated that the mean trans-18∶2 isomer content was 0.58%, ranging from 0.9 to 3.4%. Small amounts of trans-18∶3 isomers (<0.3%) were observed in 18 of the 22 shortenings studied; the maximal value was <2%. The mean value of the fraction saturated+TFA of shortenings was high (59.95±12.73%), including two values higher than 83%.     

Performance evaluation of hexane-extracted oils from genetically modified soybeans

Soybeans produced by induced mutation breeding and hybridization were cracked, flaked and hexane-extracted, and the recovered crude oils were processed to finished edible oils by laboratory simulations of commercial oil-processing procedures. Three lines yielded oils containing 1.7, 1.9 and 2.5% linolenic acid. These low-linolenic acid oils were evaluated along with oil extracted from the cultivar Hardin, grown at the same time and location, and they were processed at the same time. The oil from Hardin contained 6.5% linolenic acid. Low-linolenic acid oils showed improved flavor stability in accelerated storage tests after 8 d in the dark at 60°C and after 8h at 7500 lux at 30°C, conditions generally considered in stress testing. Room odor testing indicated that the low-linolenic oils showed significantly lower fishy odor after 1 h at 190°C and lower acrid/pungent odor after 5 h. Potatoes were fried in the oils at 190°C after 5, 10 and 15 h of use. Overall flavor quality of the potatoes fried in the low-linolenic oils was good and significantly better after all time periods than that of potatoes fried in the standard oil. No fishy flavors were perceived with potatoes fried in the low-linolenic oils. Total volatile and polar compound content of all heated oils increased with frying hours, with no significant differences observed. After 15 h of frying, the free fatty acid content in all oils remained below 0.3%. Lowering the linolenic acid content of soybean oil by breeding was particularly beneficial for improved oil quality during cooking and frying. Flavor quality of fried foods was enhanced with these low-linolenic acid oils.     

掺废橡胶微粒的再生混凝土物理力学性能

为了探索综合利用废弃混凝土和废弃轮胎2种废弃材料的可行性,研究了掺加废橡胶微粒的再生混凝土的物理力学性能.试验结果表明,橡胶微粒的掺入改善了新拌再生混凝土的工作性,显著减小了橡胶集料再生混凝土的密度,但其强度随之降低,与橡胶集料混凝土相近.经聚合物改性,水泥水化产物和橡胶微粒之间形成一层聚合物膜"桥",改善了水泥石结构形态,提高了橡胶集料再生混凝土的延性.     

高温后再生混凝土的残余抗折强度

完成了150块不同再生粗骨料取代率（0%、30％、50%、70％、100％）下再生混凝土棱柱体试块在20℃～800℃下的高温试验。通过对高温中和高温后试验现象与数据的对比,研究了高温后再生混凝土的残余抗折强度,分析了高温后再生混凝土的残余抗折强度与经历温度之间的相互关系与变化特点,同时与已有高温后再生混凝土的残余抗压强度进行了对比分析。最后,提出了基于试验统计的再生混凝土残余抗折强度与经历温度之间的建议公式。结果表明：随经历温度的升高,高温后再生混凝土的残余抗折强度整体上逐渐下降;与残余抗压强度相比,再生粗骨料取代率对高温后再生混凝土的残余抗折强度影响不明显。