循环伏安法在润滑油检测中的应用

介绍了循环伏安法的产生背景、原理。应用该技术可以快速、方便地对润滑油中抗氧剂、总酸（碱）值进行测定，并且可以对不同厂家润滑油的抗氧剂包进行区别。该技术还可以有效地评价润滑油的使用寿命和设备工作状况。     

Accumulation of thiobarbituric acid‐reactive substances in cured pork sausages treated with propolis extracts

Propolis collected by bees has many components that possess antifungal, anticancer and antioxidant properties. Cured ground pork meat was treated separately with 0.4% w/w ethanol‐extracted propolis (EEP 0.4%), 0.6% w/w water‐extracted propolis (WEP 0.6%), 0.8% w/w dried residue of ethanol‐extracted propolis (DREEP 0.8%) and 0.1% w/w potassium sorbate (PS 0.1%) and made into sausages. Thiobarbituric acid‐reactive substances (TBARS) were measured in the sausages to assess the effects of storage at 5, 10 and 20 °C after 0, 2 and 4 weeks. After 4 weeks of storage at 5 °C the sausages treated with EEP 0.4%, DREEP 0.8%, WEP 0.6% and PS 0.1% yielded TBARS values which were 50, 59, 35 and 91% respectively of the control value. There was an increase of 0.33 mg MDA kg^?1, the lowest of all treatments, in TBARS for the 0.4% w/w EEP‐treated sausages. The curing process will control microbiological spoilage, as will potassium sorbate. © 2002 Society of Chemical Industry     

Retaining maximum antioxidative potency of wheat germ oil refined by molecular distillation

A process of physical refining wheat germ oil using the technique of molecular distillation (MD) is presented in this work. Wheat germ oil was obtained from the germ by solvent extraction using hexane and also by cold pressing. The oil extracted with hexane was degummed and bleached before deacidification in order to modify the parameters of phosphorus and color. The goal in carrying out the stage of physical refining by MD was to preserve the maximum amount of original antioxidative potential obtained from extraction of the crude oil. The effect of evaporation temperature of one‐stage MD on the efficiency of free fatty acid elimination was studied. The antioxidant portion was followed by means of analytic determination of tocopherols by high‐performance liquid chromatography. Tocopherol retention up to 98% was achieved in the oil extracted by pressing, and yields of up to 96% were achieved in the oil extracted with hexane. Copyright © 2007 Society of Chemical Industry     

Diet and Health: Apple Polyphenols as Antioxidants

The traditional American rhyme says, “an apple a day keeps the doctor away.” What has made apples exceptional and appreciated for a million years? Besides their content of pectin, vitamins and minerals, they are considered to be a good source of antioxidants that scavenge and neutralize free radicals, which in turn play a role in the onset of cardiovascular diseases and cancers. Polyphenols are major antioxidants in apples, however, the antioxidants vary with the apple variety, and the post-harvest storage conditions. Further, the polyphenols are distributed differently throughout the fruit (skin or flesh). The paper reviews the present knowledge on apple polyphenols, their bioavailability and pro-health functionality.     

On the kinetics of the autoxidation of fats: influence of pro‐oxidants,antioxidants and synergists

The influence of minor amounts of pro‐ and anti‐oxidants on the kinetics of the autoxidation of fat has been evaluated. The reaction rates of oxygen with the substrates were found to follow the same basic equation, hitherto established for pure substrates. There is evidence that the surface of the reaction vessel also acts as a reaction catalyst and its effect is proportional to the area of glass in contact with lipids. Oxidation is enhanced by trace metal ions as well as by surface‐active compounds (e.g. hydroperoxides and sterols). Antioxidants such as α‐tocopherol and butylated hydroxyanisole inhibit the oxidation by delaying the start of oxygen consumption (the induction period) while retarders like amino acids only decrease the rate of oxidation. Thus pro‐ and anti‐ oxidants affect either the start or the rate of oxygen consumption. The empirical formula dx/dt = k [O₂] (1‐x/n) f′(t) was found applicable to the different stages of oxidation.     

Fractionation and characterisation for antioxidant activity of hydrolysed whey protein

Whey protein isolate (WPI) was hydrolysed for 1 h using Alcalase, Protamex and Flavourzyme. Native WPI, hydrolysed WPI and two commercial WPI hydrolysates were subjected to fractionation by size exclusion chromatography. Antioxidant activity of WPI fractions was measured with a liposome‐oxidising system (50 µM FeCl₃/0.1 µM ascorbate, pH 7.0). Lipid oxidation was measured as thiobarbituric acid‐reactive substances (TBARS). Gel electrophoresis and amino acid analysis were run to identify the peptide composition. The influence of amino acid composition on antioxidant activity was evaluated using multivariate analysis methods (correlation analysis, principal component analysis, multiple linear regression and discriminant analysis). TBARS assays indicated the presence of antioxidant activity in all protein fractions, including non‐hydrolysed WPI. For native and hydrolysed WPI samples the first fraction (> 45 kDa) showed a higher TBARS inhibition effect (24–27%) when compared with lower‐molecular‐weight fractions and hydrolysate mixtures. In contrast, for commercial WPI hydrolysates a higher inhibitory effect was found in most of the lower‐molecular‐weight fractions (30–55%). The ability of WPI fractions to delay lipid oxidation was found to be related to the prevalence of histidine and hydrophobic amino acids. Copyright © 2004 Society of Chemical Industry     

Prevention of Lipid Oxidation in Precooked Turkey Meat Patties with Hot Packaging and Antioxidant Combinations

The effects of antioxidants or hot packaging and their combination on lipid oxidation were quite variable depending on the additives in turkey meat. The TBARS values of cooked patties were greatly affected by the degree of oxidation in the raw meat, and the effectiveness of antioxidants varied with added prooxidants. Ascorbate and free radical terminators had stronger antioxidant effects than iron chelators, and chelating iron alone could not eliminate lipid oxidation in either raw or cooked meat with added NaCl. The combination of hot packaging and antioxidants provided cooked patties with better protection from lipid oxidation than either treatment alone.     

Antioxidant efficacy of amino acids in methyl linoleate at different relative humidities

Antioxidant efficacy of the amino acids methionine, tryptophan, aspartic acid, serine, alanine and arginine in methyl linoleate were compared to a methyl linoleate control at 2,50 or 79% relative humidity (RH) at 37°C. Antioxidant efficacy varied with RH and the individual amino acids. Arginine had the highest antioxidant efficacy at all RH values compared to the control. The efficacy of alanine was equal to that of arginine at RHs of 50 and 79% but was lower at 2% RH. The presence of aliphatic, alkaline amino, hydroxyl or thiol groups in the side chain of the amino acids increased the antioxidant efficacy at high RHs.     

药物抗氧化作用对DNA发光动力学行为的影响

本文应用ＣｕＳＯ４－Ｐｈｅｎ－Ｖｃ－Ｈ２Ｏ２－ＤＮＡ化学发光体系观察药物对发光动力学行为的影响，研究了九种药物对ＤＮＡ损伤的保护作用，并对其药物结构对抗氧化能力的影响进行了分析。发现药物在该系统中的抗氧化作用有三种类型，提示它们可能在体内不同的反应过程中起不同的作用。在该系统中具有抑制ＤＮＡ损伤发光能力的药物，按其作用强弱依次为阿魏酸、丹参素、芦丁，茶多酚、ＳＯＤ、、丹参酮Ⅱ－Ａ，丹皮酚，五味子乙     

Antioxidant properties and composition of Majorana syriaca extracts

Majorana syriaca is an important food‐flavouring ingredient in the Middle Eastern culture known commonly as Za'atar. The components of the plant were extracted in a Soxhlet apparatus sequentially with solvents of increasing polarity, specifically with petroleum ether (P), diethyl ether (D), ethyl acetate (EAc), and ethanol (E). The activity of the extracts to scavenge the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH^?) followed the order D > E > EAc > P. Moreover, the antioxidant activity in corn oil at concentrations of 200, 500 and 1000 ppm was monitored through peroxide value and conjugated hydroperoxide measurements and revealed that D and E extracts resulted in the highest protection followed by EAc and P extracts. Increasing the concentration from 200 to 500 ppm depressed peroxide formation, while a further increase had no effect. The main components of the P extract according to GS‐MS analysis were thymol (42.89%) and carvacrol (42.75%). The remaining extracts comprise flavonoids and phenolic acids that provide the antiradical and antioxidant activity.