三种黄酮类化合物抗自由基的研究

通过连苯三酚法测定金银花和葛根超声波提取液清除超氧自由基的能力。结果表明：金银花和葛根提取液其清除超氧自由基的能力与作用时间成反比,抗超氧自由基的能力与提取液浓度成正比。通过DPPH法测定金银花、葛根和栗子叶提取液清除自由基的能力。结果表明：它们清除能力与提取液浓度成正比,提取液清除自由基的能力为：金银花〉葛根〉栗子叶。     

Effect of 5-caffeoylquinic acid on soybean oil oxidative stability

The antioxidant activity of 5-caffeoylquinic acid (5CQA) at concentration ranges of 0.01–0.08% (w/w) was compared with 0.02% (w/w) butylated hydroxytoluene (BHT) in soybean oil. The oil was stored in air at 55  °C and monitored by peroxide and conjugated diene measurements. Both 0.01% and 0.02% 5-CQA showed lower peroxide values than BHT only on the first day. However, on days 1, 2, 3 and 4, 0.04% 5-CQA reduced the peroxide value to 68%, 47%, 45% and 90% of that observed with BHT. Use of 5-CQA appears to delay the formation of peroxides and up to 0.04% (w / w) its antioxidative action increases with concentration for up to 3 days.     

脂肪醇乙氧基化物的高温稳定性（英）

研究在脂肪醇乙氧基化物储存和搬运时的氧化稳定性。用在静止空气中加热的方法来模拟实际的条件。通过带有质谱检测的温差测重法和带有气相取样的差示扫描量热法来膜拟更为精确的、充分通气的条件。     

水份与油品质量

众所周知，水份调节是油脂制备的关键。然而，水份与油品质量的关系长期未被充分重视。最近的研究表明：水份是控制油品中非水化磷脂含量的重要条件，适当保持油品水份可以有效地降低油脂氧化速度。     

Enzymatic and Autoxidation of Defatted Peanuts

Ground, blanched, raw, and roasted peanuts with varying oil contents were analyzed for oxidation products. Peroxide values (PV) of blanched, ground raw (BRAW) peanuts, demonstrating enzymatic oxidation, and heat-treated rancid roasted peanuts (RRST), demonstrating autoxidation, exhibited decreases (p ≦ 0.05) with decreasing oil content. The Oxidative Stability Index (OSI) time at 110 °C increased (p < 0.05) with decrease in oil content of raw (BRAW) and roasted (BRST) ground peanuts. A higher OSI indicated more oxidative stability, thereby supporting the hypothesis of higher potential for autoxidation at higher oil contents. In addition, BRST exhibited a shorter OSI than BRAW, indicating slower autoxidation in BRAW. Roasted peanutty odor, burnt odor, and roasted peanutty flavor, rancid/oxidized flavor, and burnt flavor scores of rancid roasted peanuts decreased (p ≦ 0.05) with decreasing oil content.     

Chemiluminescence as a method for oxidative rancidity assessment in autoxidized marine oils

Chemiluminescence based on light emission from excited oxygen species,e.g. singlet oxygen and triplet carbonyls, has been used to measure the oxidative rencidity of fish oils. The luminescence was recorded after sodium hypochlorite addition to the oils dissolved intert-butanol. In addition to high sensitivity and ability to detect small changes in rancidity, the method is fast and may be used as a supplement to the standard chemical methods for quality assessment and antioxidant evaluation. However, care has to be taken in interpretation of the chemiluminescence data of different fish oils, as the light emission depends on both the composition and the rancidity level of the oil. The autoxidized oils were also characterized by peroxide value, thiobarbituric acid value, anisidine value, Kreis rancidity index, iodine value, ultraviolet measurements, capillary gas chromatography, size-exclusion chromatography and sensoric evaluation.     

The role of amino acids in the autoxidation of milk fat

The effects of amino acids and their analogs on milk fat oxidation were examined under various conditions by measuring oxygen consumption and total unsaturated fatty acids. All the amino acids tested acted as antioxidants, characteristically extending the induction period (IP). Not only primary amino groups are responsible for the antioxidative activities of amino acids, but also the side-chain groups contribute, at least partially, to the protective effects of L-cysteine, L-tryptophan and L-tyrosine. In aqueous and HCL solutions, the antioxidative effects of L-alanine were significantly reduced. The freeze-dried L-lysine-HCL and L-alanine-HCL accelerated, while the corresponding control amino acids inhibited, milk fat oxidation.     

邻苯三酚自氧化法测定抗氧化活性的方法研究

通过对邻苯三酚自氧化反应体系的光谱吸收、缓冲液pH值和邻苯三酚浓度对自氧化速率的影响进行研究,建立邻苯三酚自氧化-分光光度法最佳应用体系。确定反应体系总体积为3mL,检测波长在319nm时的测定条件为：缓冲液pH值7．3,邻苯三酚浓度60mmol／L,自氧化速率可达0．060△A／min,线性时间4min;检测波长在420nm时的测定条件为：缓冲液pH值7．8,邻苯三酚浓度80mmol／L,自氧化速率可达0．050△A／min、线性时间3min。新方法建立的紫外和可见光两种检测波长体系,可针对样品的吸收光谱特征选择检测波长,避免了样品自身吸收强对测定检测限的影响,测定pH值接近生物体内真实条件,自氧化速率为最佳检测值且线性时间良好。     

The Thiobarbituric Acid (TBA) Reaction in Foods: A Review

The wide diffusion of 2-thiobarbituric acid (TBA) in the scientific literature is due to the TBA assay, or TBA test, which has been employed in the determination of autoxidative alterations of fats and oils. Two processes occur in autoxidation, generally: the free radical and the photo-oxidation mechanisms. The better studied is the free radical mechanism. The hydroperoxiepidioxides and bicycloendoperoxides are malonaldehyde (MDA) precursors. The absorption spectrum obtained with oxidized fatty foods is like the spectrum obtained when TBA and MDA react. However, during the secondary phase of the autoxidation process other aldehydes (alkanals, 2-alkenals, dienals) are formed which react with TBA, and they are responsible for off-flavors. Three kinds of pigments (yellow, orange, red adducts) are involved. Also, aromatic aldehydes, which constitute the flavor profile of diverse fruits and essential oils, form with TBA the characteristic arylidene-2-TBA acids. Other substances, such as ketones, ketosteroids, acids, esters, sugars, imides and amides, amino acids, oxidized proteins, pyridines, pyrimidines, and vitamins can react with TBA; they are named TBARS (substances that react with TBA), and form principally in meats and meat derivatives. Several organic or bio-organic acids, as shikimic and sorbic acids, react photometrically with TBA if a Malaprade reaction takes place before. A structural study of the red adduct TBA-MDA has been carried out.