Thermal antioxidative kinetics of sesamol in triacylglycerols and fatty acid methyl esters of sesame,olive, and canola oils

Oxidation kinetics of the triacylglycerols (TAGs) and fatty acid methyl esters (FAMEs) of sesame, olive, and canola oils were studied in the presence of the different concentrations of sesamol (0.1%–0.16%) at 60, 80, and 100°C. Sesamol increased the temperature coefficient, T_C, and Q₁₀ number of the TAGs more significantly compared to the FAMEs. All the sesamol-added TAG and FAME systems, respectively, of the olive, canola, and sesame oils, respectively, exerted increased values of the Arrhenius (activation energy, E_a, and frequency factor, A) and Eyring (enthalpy, ΔH⁺⁺, and entropy, ΔS⁺⁺) equation parameters. Sesamol improved the Gibbs free energy (ΔG⁺⁺) of the activated complex formation in the canola, sesame, and olive systems, respectively, and the effect was greater in the FAMEs.     

芝麻及芝麻油中主要抗氧化物质的研究进展

芝麻及芝麻油都含有抗氧化物质,其中起着抗氧化作用的主要是酚类物质.主要介绍芝麻及芝麻油中的主要抗氧化物质、生理功能和它们的提取方法.     

芝麻香油风味成分

芝麻香油的风味成分是吡嗪、呋喃、噻唑、噻吩、吡咯,以及醇、醛、酮、酸、酯类等化合物.用葡萄糖、半胱氨酸、精氨酸和水解芝麻蛋白,在145℃温度下加热40 min,可以产生接近焙炒芝麻的风味,香气中的主要物质是2-乙基-5-甲基吡嗪、乙酰呋喃、2-乙酰噻唑、5-乙基-4-甲基噻唑.这些香气成分沸点低,因此芝麻香油不适于煎炸,而且生产芝麻香油温度过高,会引起诸多营养物质劣变,将影响芝麻的资源利用.机榨、低温压榨和水酶法制取的芝麻油,油品用途广,并能综合开发蛋白质、维生素和芝麻木酚素等营养成分.     

芝麻素及其衍生物与DNA相互作用的研究

在pH=7.4的生理条件下,采用紫外吸收光谱法、圆二色(CD)光谱法、DNA热变性法及粘度法对芝麻提取物芝麻酚(SL)、芝麻素(SN)及细辛脂素(AN)与小牛胸腺DNA(ctDNA)的相互作用机理进行初步探讨。研究结果显示,ctDNA能使三种化合物在290 nm附近处的紫外吸收峰产生减色效应,且伴随轻微的红移现象,ctDNA浓度越大,减色效应越明显,SL、SN及AN与ctDNA的结合常数大小分别为2.65×10~4、4.91×10~4、7.33×10~4 L/mol;三种化合物均能使ctDNA的正CD带(276 nm)增加,负CD带(246 nm)发生轻微的减小,且浓度越大,谱带变化越明显;三种化合物的存在条件下,ctDNA的熔点分别增加了1.75、2.51和6.63℃,且ctDNA粘度均有所增加。综合光谱学和粘度实验的结果,推断三种化合物与DNA的作用方式均为经典的嵌插方式,且作用强度大小为:ANSNSL。     

常压室温等离子体诱变选育高产油脂皮状丝孢酵母的研究

研究了常压室温等离子体(ARTP)诱变时间对皮状丝孢酵母(Trichosporon cutaneum)致死率的影响,考察了不同质量浓度芝麻酚对皮状丝孢酵母生长的抑制程度,建立了一种快速高效选育高产油脂菌株的方法。结果表明:经过ARTP的40 s诱变后,接种到质量浓度为0. 15 mg/m L的芝麻酚培养基中28℃培养2 d,筛选出生长旺盛的菌株,然后接种到48孔液体培养基培养,并利用96孔板尼罗红荧光染色对培养菌株进行高通量筛选,选育出一株高产油脂菌株Trichosporon cutaneum A1。该菌株较原始菌株的生物量、油脂产量、油脂含量分别提高了41. 6%、123. 1%、57. 4%,且具有较好的遗传稳定性;通过气相色谱分析,其油脂脂肪酸组成与原始菌株相同,均为十六烷酸、硬脂酸、油酸、亚油酸。说明建立的芝麻酚抗性筛选和荧光标记高通量筛选相结合的ARTP选育方法是可行的,为其他产油脂菌株的筛选提供重要参考。     

验证芝麻酚的抗氧化性质

现代技术研究表明，芝麻中含有多种具有抗氧化作用的物质。芝麻经过正己烷脱脂、乙醇提取等方法处理，可以得到含有芝麻酚的提取物。然后利用2-硫代巴比妥酸检测提取物的抗氧化能力。     

芝麻酚调控巨噬细胞极化改善肥胖小鼠脂肪组织炎症及胰岛素抵抗

目的：探讨芝麻酚能否通过调控巨噬细胞极化改善肥胖小鼠脂肪组织炎症及胰岛素抵抗。方法：建立高脂饲料喂饲的肥胖小鼠模型,灌服芝麻酚（100 mg/kg）8周,行腹腔糖耐量及胰岛素耐量试验后处死小鼠,测血脂和胰岛素水平。免疫印迹检测附睾脂肪组织P-AKT和P-JNK蛋白表达。脂肪组织切片行F4/80及Cd11c免疫组化及免疫荧光染色。实时荧光定量PCR测脂肪组织细胞因子及趋化因子mRNA表达。结果： 芝麻酚治疗后降低肥胖小鼠体质量及血脂水平,改善糖耐量损伤及胰岛素抵抗。芝麻酚治疗组小鼠脂肪组织巨噬细胞浸润减少,P-AKT表达恢复,P-JNK表达降低,M1型巨噬细胞标志物（Cd11c、iNOS、TNF-α和IL-6）mRNA表达减少,M2型标志物（Chi3l3、Arg1和Mgl1）mRNA表达增加。结论：芝麻酚减轻肥胖小鼠脂肪组织炎症和胰岛素抵抗,其作用与芝麻酚抑制脂肪组织JNK信号通路,改善巨噬细胞极化失衡状态有关。     

Effects of Ascorbic Acid and Antioxidants on the Lipid Oxidation and Volatiles of Irradiated Ground Beef

Beef loins, aged for different lengths of time post slaughter, were treated with ionizing radiation. Irradiated ground beef produced volatile sulfur compounds (S‐volatiles) responsible for the unique irradiation odor and accelerated lipid oxidation. The quality changes by irradiation became greater as aging and storage time increased. During aerobic storage, the S‐volatiles disappeared whereas volatile aldehydes drastically increased in irradiated beef. Addition of ascorbic acid at 0.1% (wt/wt) or sesamol +α‐tocopherol at each 0.01% level to ground beef before irradiation effectively reduced lipid oxidation and S‐volatiles. As storage time increased, however, the antioxidant effect of sesamol + tocopherol in irradiated ground beef was superior to that of ascorbic acid.     

Antioxidant Effects of Sesamol Released from Polymeric Films on Lipid Oxidation in Linoleic Acid and Oat Cereal

The antioxidant effects of sesamol films were evaluated using a food simulant (linoleic acid) and a real food (oat cereal). Sesamol was melt blended with high density polyethylene, linear low density polyethylene and ethylene‐vinyl acetate resins using co‐extrusion to produce sesamol films of multilayer structure; for comparison, films containing butylated hydroxytoluene (BHT) or no additive (as control) were also produced. At least 60% of the initial amount of sesamol remained in the films after extrusion. The release of sesamol from the sesamol films was about six times faster at 30°C than at 10°C. The antioxidant effectiveness of sesamol and BHT was evaluated on the basis of induction period of lipid oxidation, conjugated dienes (for linoleic acid), hexanal (for oat breakfast) and sensory evaluation. Compared with the control film, the sesamol films extended the induction period of linoleic acid by five and eight times at 40°C and 23°C, respectively. After 12 month storage at 23°C, hexanal formation was 59% less in cereal packaged with sesamol films than that packaged with control film. Rancid odours were detected in cereal packaged with control films, but not with sesamol or BHT films. The incorporation of sesamol had only slight effects on tensile properties and transparency. Copyright © 2012 John Wiley & Sons, Ltd.