High‐Purity Tocored Improves the Stability of Stripped Corn Oil Under Accelerated Conditions

γ‐Tocopherol‐5,6‐quinone (tocored) is of importance among the γ‐tocopherol (γ‐T) oxidant products and found in corn germ oil. Investigation on tocored is impeded in part by the difficulty to access high purity tocored. In this present study, high‐purity tocored is successfully prepared, and its antioxidant activity, together with γ‐T and TBHQ (positive control) in increasing concentrations in stripped corn germ oil is evaluated by Rancimat and Schaal oven tests. The stabilization factor in the Rancimat tests increases significantly (p < 0.05) along with an increase in the levels of antioxidants. Furthermore, tocored exhibits higher stabilization than γ‐T in the Schaal oven tests, although its efficacy gradually increases up to 100 mg kg^–1 and decreases significantly at higher levels (from 100 to 500 mg kg^–1), drawn from the comprehensive parameter A (considering both efficiency and strength) changes (5.06–11.21). In addition, the curves illustrating the residual contents of tocored and γ‐T run in different ways when the four levels are taken into consideration, further bearing the above results. Tocored tends to be a potent natural antioxidant for edible corn germ oil preservation. Practical Application: The present work provides more clear procedures for high‐purity tocored synthesis. Furthermore, tocored may be a potential natural antioxidant that is especially suitable for lipid base food substrates. The results of the present work contribute to the deeper understanding of the antioxidant activity of γ‐tocopherol. The antioxidant activity of tocored is higher than γ‐tocopherol in Schaal oven test. Tocored is a bright orange‐red substance that affects the appearance of the edible oil. Meanwhile, γ‐tocopherol is well known for its valuable health benefits, and appropriate measures should be adopted to store oils (corn oil, soybean oil, and so on) rich in γ‐tocopherol to control transformation in order to keep stability optimal. To some degree, the practical applications of the present results are also related to the processing and storage of edible oils.     

液质联用分析常见植物油甘油三酯

采用高效液相色谱-串联飞行时间质谱法分析了常见植物油如大豆油、芝麻油、花生油、特级初榨橄榄油、葵花籽油、玉米油、油茶籽油、棉籽油和菜籽油的甘油三酯。结果显示每种植物油甘油三酯的种类和含量均不相同。该方法测定甘油三酯有效可行,可为甘油三酯结构信息研究及油脂掺伪鉴别提供基础支持。     

Rapid Quantification of Low-Viscosity Acetyl-Triacylglycerols Using Electrospray Ionization Mass Spectrometry

Acetyl‐triacylglycerols (acetyl‐TAG) possess an sn‐3 acetate group, which confers useful chemical and physical properties to these unusual triacylglycerols (TAG). Current methods for quantification of acetyl‐TAG are time consuming and do not provide any information on the molecular species profile. Electrospray ionization mass spectrometry (ESI–MS)‐based methods can overcome these drawbacks. However, the ESI–MS signal intensity for TAG depends on the aliphatic chain length and unsaturation index of the molecule. Therefore response factors for different molecular species need to be determined before any quantification. The effects of the chain length and the number of double‐bonds of the sn‐1/2 acyl groups on the signal intensity for the neutral loss of short chain length sn‐3 groups were quantified using a series of synthesized sn‐3 specific structured TAG. The signal intensity for the neutral loss of the sn‐3 acyl group was found to negatively correlated with the aliphatic chain length and unsaturation index of the sn‐1/2 acyl groups. The signal intensity of the neutral loss of the sn‐3 acyl group was also negatively correlated with the size of that chain. Further, the position of the group undergoing neutral loss was also important, with the signal from an sn‐2 acyl group much lower than that from one located at sn‐3. Response factors obtained from these analyses were used to develop a method for the absolute quantification of acetyl‐TAG. The increased sensitivity of this ESI–MS‐based approach allowed successful quantification of acetyl‐TAG in various biological settings, including the products of in vitro enzyme activity assays.     

Modulation of the antioxidant/pro-oxidant balance,cytotoxicity and antiviral actions of grape seed extracts

Grape seed extracts (GSEs) were investigated in yeast cells harbouring defects in their antioxidant system (regarding the cellular growth and growth recovery from H₂O₂ insult). GSEs antioxidant activity was detected in wild-type and mutant strains Δcta1, Δgsh1 and Δoye2glr1, while pro-oxidant activity in Δsod1 cells was seen. Assessment of proliferation of prostate cancer PC3 and HBV-replicating HepG2 2.2.15 cells treated with GSEs has shown higher cytotoxicity of red grape seed extract (RW) than white grape seed extract (WW) subjective to dose and period of administration. No antiviral effect was detected by measuring the secreted virion particles in HepG2 2.2.15 cells treated with GSEs. The GSEs play a dual antioxidant/pro-oxidant role in vivo according with the cellular antioxidant system deficiencies and exhibit cytotoxic properties in PC3 and HepG2 2.2.15 cell lines, but no antiviral action against HBV.     

Rheological characterization of yellow grease and poultry fat

The rheological properties of yellow grease and poultry fat and their liquid density at 25.0°C were experimentally determined. Dynamic viscosities of these industrial recycled fat products were measured for shear rates of 0.65 to 32.34 s⁻¹ at temperatures of 15.6 to 71.1°C. The resulting measurements were fitted to a power law model to obtain values for the consistency coefficient and the flow behavior index. The data was also fit to Andrade's equation to relate viscosity to temperature. These results indicated pseudoplastic flow behavior for both products, with increasing non-Newtonian behavior at higher temperatures and shear rates.     

几种真菌油脂的分析

在实验室条件下培养提取所得的几种真菌油脂经水解后进行薄层层析 ,结果表明油溶性成分因菌种而异 ;脂肪酸分析表明在不同培养条件下菌种脂结构也不同 ;对土生假丝酵母在优化条件下合成的类可可脂经甘三酯组成测定和差示扫描量热法分析 ,证明了此条件下所产的类可可脂是较理想的类可可脂     

Conjugated linoleic acid and vaccenic acid in rumen, plasma, and milk of cows fed fish oil and fats differing in saturation of 18 carbon fatty acids

The objective of this study was to examine the effect of feeding fish oil (FO) along with fat sources that varied in saturation of 18 carbon fatty acids (high stearic, high oleic, high linoleic, or high linolenic acids) on rumen, plasma, and milk fatty acid profiles. Four primiparous Holstein cows at 85 d in milk (+/- 40) were assigned to 4 x 4 Latin squares with 4-wk periods. Treatment diets were 1) 1% FO plus 2% commercial fat high in stearic acid (HS); 2) 1% FO plus 2% fat from high oleic acid sunflower seeds (HO); 3) 1% FO plus 2% fat from high linoleic acid sunflower seeds (HLO); and 4) 1% FO plus 2% fat from flax seeds (high linolenic; HLN). Diets were formulated to contain 18% crude protein and were composed of 50% (dry basis) concentrate mix, 25% corn silage, 12.5% alfalfa silage, and 12.5% alfalfa hay. Milk production, milk protein percentages and yields, and dry matter intake were similar across diets. Milk fat concentrations and yields were least for HO and HLO diets. The proportion of milk cis-9, trans-11 conjugated linoleic acid (CLA; 0.71, 0.99, 1.71, and 1.12 g/100 g fatty acids, respectively), and vaccenic acid (TVA; 1.85, 2.60, 4.14, and 2.16 g/100 g fatty acids, respectively) were greatest with the HLO diet. The proportions of ruminal cis-9, trans-11 CLA (0.09, 0.16, 0.18, and 0.16 g/100 g fatty acids, respectively) were similar for the HO, HLO, and HLN diets and all were higher than for the HS diet. The proportions of TVA (2.85, 4.36, 8.69, and 4.64 g/100 g fatty acids, respectively) increased with the HO, HLO, and HLN diets compared with the HS diets, and the increase was greatest with the HLO diet. The effects of fat supplements on ruminal TVA concentrations were also reflected in plasma triglycerides, (2.75, 4.64, 8.77, and 5.42 g/100 g fatty acids, respectively); however, there were no differences in the proportion of cis-9, trans-11 CLA (0.06, 0.07, 0.06, and 0.07 g/100 g fatty acids, respectively). This study further supports the significant role for mammary delta-9 desaturase in milk cis-9, trans-11 CLA production.     

Screening catalytic lipase activities with an analytical supercritical fluid extractor

Two different screenings of several commercial lipases were performed to find a lipase with superior performance for the conversion of lipid moieties to their fatty acid methyl ester (FAME) derivatives under supercritical conditions. The first screening was done under hydrolytic conditions in a buffer. The second screening was done under supercritical conditions with CO₂, utilizing some of the same lipases for the methanolysis of different lipids. For the substrates studied, there was a significant difference in lipase activity under the two above conditions. Significant hydrolytic activity was demonstrated for three different lipid types (triglycerides, sterols, and phospholipids) with Lipase PS30, but when the same lipase was immobilized on an Accurel carrier (polypropylene), the activity decreased considerably. The opposite was found for Lipase G, which showed strong activity when immobilized and under supercritical conditions. Furthermore, Chirozyme L-1 was superior under supercritical conditions. The altered substrate specificity that some of these lipases show in supercritical CO₂ suggests several interesting synthetic options and applications under these conditions.     

Dynamic polymorphic phase transitions in a model binary triglyceride system measured by position-sensitive X-ray diffraction methods

X-ray diffraction measurements have been made on a binary mixture of pure tripalmitin and tristearin which undergoes particular polymorphic phase transitions on heating from the solid. The results were obtained using a position-sensitive detector which can record the whole diffraction pattern in time periods less than a minute. This allows many patterns to be recorded during the transformations where heating rates can be up to several^oC/min. As such the transitory existence of the intermediate β' phase has been unambiguously identified. The results serve to exhibit the usefulness of the X-ray apparatus and indicate its potential for future studies in dynamic crystallization and melting. On behalf of Loders-Croklaan     

Solid fat content determination using ultrasonic velocity measurements

The ultrasonic group velocity has been measured through 0–20% mass fraction samples of tristearin, tripalmitin, trilaurin and 1-oleodipalmitin suspended in paraffin oil at 25°C and 1 MHz. For tristearin, tripalmitin and trilaurin there is an increase of about 3.1 m/sec per 1% increase in insoluble triglyceride in suspension. For trilaurin and 1-oleodipalmitin there is a slight decrease in velocity with increasing soluble triglyceride. The technique may, therefore, prove useful for determination of solubilities of triglycerides in suspension, as well as for determining solid fat contents. For the tristearin/paraffin oil suspensions there is a good correlation between the solid content added and that predicted by a theoretical formula available in the literature (correlation = 0.998 for twenty samples). The reproducibility of the solid fat content determination is 0.2%, the accuracy is about 0.6%. The technique is easily automated, cheap, accurate, rapid and non-intrusive and should, therefore, prove useful both as an in-line quality control monitoring device and as a new instrumental technique for research applications.