Adsorption isotherms of sesame oil in a concentrated miscella system

The adsorption of peroxides, unsaturated carbonyls, free fatty acids and carotenoids from unrefined sesame oil on vegetable carbon (5%, w/w) in a miscella system was studied. Three different solvent conditions (hexane/ethanol, 100:0, 95:5 and 75:25, vol/vol), combined in a factorial design with five levels of solvent (0, 10, 20, 30 and 40%, w/w), were used to develop the miscella. Equilibrium adsorption was not achieved during the 100 min of adsorption, mainly because the oil components were involved in oxidation reactions during the adsorption process. However, for a given solvent concentration, adsorption of the oil components showed a significant linear regression on their respective initial concentration in the miscella (C_i). Peroxides and carbonyls showed, at all solvent levels investigated, an affinity for the carbon more independent of their C_i than free fatty acids and carotenoids. In general, at the same C_i, a higher adsorption was achieved as solvent concentration increased. The results indicated that free fatty acid adsorption may depend on competitive adsorption based on molecule hydrophobicity. However, in spite of the higher hydrophobicity of carotenoids, compared with free fatty acids, they might not be competing for the same adsorbing sites. Ethanol showed a prooxidant effect that increased peroxide production during adsorption but did not affect the reaction involved in carbonyl production.     

Lignan contents in sesame seeds and products

Sesame seed (Sesamum indicum L.) is a rich source of furofuran lignans with a wide range of potential biological activities. The major lignans in sesame seeds are the oil‐soluble sesamin and sesamolin, as well as glucosides of sesaminol and sesamolinol that reside in the defatted sesame flour. Upon refining of sesame oil, acid‐catalyzed transformation of sesamin to episesamin and of sesamolin to epimeric sesaminols takes place, making the profile of refined sesame oils different from that of virgin oils. In this study, the total lignan content of 14 sesame seeds ranged between 405 and 1178 mg/100 g and the total lignan content in 14 different products, including tahini, ranged between 11 and 763 mg/100 g. The content of sesamin and sesamolin in ten commercial virgin and roasted sesame oils was in the range of 444–1601 mg/100 g oil. In five refined sesame oils, sesamin ranged between 118 and 401 mg/100 g seed, episesamin between 12 and 206 mg/100 g seed, and the total contents of sesaminol epimers between 5 and 35 mg/100 g seed, and no sesamolin was found. Thus, there is a great variation in the types and amounts of lignans in sesame seeds, seed products and oils. This knowledge is important for nutritionists working on resolving the connection between diet and health. Since the consumption of sesame seed products is increasing steadily in Europe and USA, it is important to include sesame seed lignans in databases and studies pertinent to the nutritional significance of antioxidants and phytoestrogens. It is also important to differentiate between virgin, roasted and refined sesame oils.     

Variations in the composition of sterols,tocopherols and lignans in seed oils from fourSesamum species

Seeds from different collections of cultivatedSesamum indicum Linn and three related wild species [specifically,S. alatum Thonn.,S. radiatum Schum & Thonn. andS. angustifolium (Oliv.) Engl.] were studied for their oil contents and fatty acid composition of the total lipids. The oils from wild seeds were characterized by higher percentages of unsaponifiables (4.9, 2.6 and 3.7%, respectively) compared toS. indicum (1.4–1.8%), mainly due to their high contents of lignans. Total sterols accounted forca. 40, 22, 20 and 16% of the unsaponifiables of the four species, respectively. The four species were different in the relative percentages of the three sterol fractions (the desmethyl, monomethyl and dimethyl sterols) and in the percentage composition of each fraction. Campesterol, stigmasterol, sitosterol and Δ⁵-avenasterol were the major desmethyl sterols, whereas obtusifoliol, gramisterol, cycloeucalenol and citrostandienol were the major monomethyl sterols, and α-amyrin, β-amyrin, cycloartenol and 24-methylene cycloartanol were the main dimethyl sterols in all species. Differences were also observed among the four species in sterol patterns of the free sterols compared to the sterol esters.Sesamum alatum contained less tocopherols (210–320 mg/kg oil), andS. radiatum andS. angustifolium contained more tocopherols (ca. 750 and 800 mg/kg oil, respectively) than didS. indicum (490–680 mg/kg oil). The four species were comparable in tocopherol composition, with γ-tocopherol representing 96–99% of the total tocopherols. The four species varied widely in the identity and levels of the different lignans. The percentages of these lignans in the oils ofS. indicum were sesamin (0.55%) and sesamolin (0.50%).Sesamum alatum showed 1.37% of 2-episesalatin and minor amounts of sesamin and sesamolin (0.01% each).Sesamum radiatum was rich in sesamin (2.40%) and contained minor amounts of sesamolin (0.02%), whereS. angustifolium was rich in sesangolin (3.15%) and also contained considerable amounts of sesamin (0.32%) and sesamolin (0.16%).     

芝麻渣中蛋白质的提取与纯化

采用超声波—微波协同提取法提取芝麻渣中蛋白质,并用超滤法进行纯化.实验考察了影响粗蛋白提取率的固液比、溶液pH值、微波功率、提取时间等因素,确定了最佳提取条件;同时考察了超滤膜的截留分子质量以及压力对超滤效果的影响.结果表明：超声波—微波协同提取最佳条件为超声波功率40 W,固液比1∶20,溶液pH11,微波功率250 W、提取时间90 s,提取率约55.32%;采用10万截留分子质量的超滤膜在0.18 MPa压力下对芝麻渣蛋白质纯化后,蛋白质纯度提高了15.67%.     

三氟乙酸对几种植物油的显色反应

以三氟乙酸为显色剂,对芝麻香油、二级棉籽油、三级棉籽油、一级菜籽油、菜籽毛油5种植物油进行显色反应,并在350~700 nm波长进行紫外-可见光谱扫描.结果显示用三氟乙酸做显色剂能够很明显地将这5种植物油区分开来,所显示的颜色分别为:黄绿色、黄橙色、暗红橙色、红紫色、暗红橙色;并且上述5种植物油显色反应后的紫外-可见光谱扫描曲线差别很大,容易区分.     

多重实时荧光定量聚合酶链式反应在芝麻酱掺假鉴别中的应用

目的 基于分子生物学技术,研究建立多重实时荧光定量聚合酶链式反应(Polymerase Chain Reaction,PCR)技术检测芝麻酱中的植物源性成分,实现芝麻酱的快速掺假鉴别,突破单标准单物种检测的局限性。方法 该研究以芝麻2S albumim mRNA基因、花生Ara b2基因、大豆Lectin基因、玉米adh1基因设计特异性引物和探针,优化反应体系,建立多重实时荧光定量PCR技术检测芝麻酱中的芝麻源性成分、花生源性成分、大豆源性成分、玉米源性成分,并应用于市售的芝麻酱样本检测分析。结果 该方法高效低成本,特异性好,对小米、绿豆等10种非目标源性成分无特异性扩增;对芝麻源性成分、花生源性成分、大豆源性成分、玉米源性成分的最低检出限为100 pg/μL,具有较高的灵敏度;应用建立的方法,对市售21份芝麻酱样本进行检测分析,检测结果与标签标注不符合的有4份,标签标注符合率80.95%,与参比方法检测结果一致。结论 建立的多重实时荧光定量PCR技术对加工成品的检测具有较好的适用性,为芝麻酱的掺假鉴别提供了一种新的分子生物学方法。     

利用面筋蛋白制取粉末油脂的研究

将芝麻香油、亲油乳化剂、面筋蛋白、乙醇等在一定条件下混合、均质 ,然后真空干燥即得到成品———芝麻香油粉末油脂 实验结果表明 :乳化剂的HLB值为 4 3,用量为 2 % ;乳化温度为 55℃ ;乙醇用量 1 40mL .并对所得产品进行了贮藏稳定性实验     

基于BP神经网络的近红外光谱法鉴别芝麻油品牌的研究

研究了一种用近红外光谱分析技术快速鉴别芝麻油品牌的方法。首先对芝麻油样品的近红外光谱采用主成分分析法进行聚类分析,加结合人工神经网络技术进行芝麻油品牌的鉴别。通过主成分分析,得到前15个主成分的累计可信度达到99.72%,再将55个校正集样品的前15个主成分数据作为BP网络输入变量,建立一个3层BP人工神经网络的芝麻油...     

Effects of Sesame Oil Addition to Soybean Oil During Frying on the Lipid Oxidative Stability and Antioxidants Contents of the Fried Products During Storage in the Dark

ABSTRACT: Effects of sesame oil addition to soybean oil during frying on the lipid oxidative stability and antioxidants contents of fried products during storage in the dark were studied. Flour dough pieces (2 cm × 2 cm × 0.1 cm) were fried at 160 °C for 1 min in sesame oil-added soybean oil. Concentrations of sesame oil in the frying oil were 0%, 10%, and 20% by volume. Fried products were put into a glass bottle, and the bottles were tightly sealed and stored at 60 °C in the dark for 18 d. Lipid oxidation of fried products was determined by fatty acid composition changes and conjugated dienoic acid (CDA) and p -anisidine (PA) values. Tocopherols and lignan compounds in the fried products were determined by high-performance liquid chromatography. Relative content of linolenic acid decreased, and CDA and PA values increased during storage of the fried products in the dark. Fatty acid composition change and CDA and PA values during storage were lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil. The results clearly showed that addition of roasted sesame oil to soybean oil at 10% and 20% during frying decreased the lipid oxidation of fried products during storage in the dark for 18 d by extension of induction period and decrease in decomposition of oxidized lipids. Fried products contained 134 to 267 ppm tocopherols and 0 to 148 ppm lignans before storage; however, their contents decreased during storage in the dark. Lignan compounds were more stable than tocopherols, and the rate of tocopherols degradation was lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil, which could be because of protection of tocopherols from degradation by lignan compounds.