磷钨杂多酸催化芝麻林素提高冷榨芝麻油的氧化稳定性

采用向冷榨芝麻油中添加芝麻酚纯品的方式验证芝麻酚的抗氧化活性;采用磷钨杂多酸(HPW)催化冷榨芝麻油中的芝麻林素分解生成芝麻酚和芝麻素酚,探索HPW添加量、反应温度、反应时间对酸催化实验的影响,从而提高冷榨芝麻油的氧化稳定性。结果表明:一定含量的纯品芝麻酚可以有效提高冷榨芝麻油的氧化稳定性,当芝麻酚的添加量达到100 mg/100 g时,冷榨芝麻油的氧化诱导时间(OSI)从原来的4.20 h延长到6.62 h;在HPW添加量0.8%、反应温度80℃、反应时间120 min条件下,芝麻林素完全分解转化,冷榨芝麻油的OSI为9.32 h;经过酸催化处理的冷榨芝麻油酸值、过氧化值、皂化值均有不同程度的上升,色泽变浅,但变化范围不大,均在国标一级芝麻油的标准范围之内,并未对冷榨芝麻油的品质造成较大的影响。     

不同产地黑芝麻及其油脂品质研究

选取7个产地的黑芝麻为原料，压榨制备黑芝麻油，分别对黑芝麻组成和黑芝麻油品质指标进行分析。结果表明：7种黑芝麻油均以油酸、亚油酸、棕榈酸和硬脂酸为主，且不饱和脂肪酸含量达到80%以上。7种黑芝麻油的总酚含量为2.31～7.35 mgGAE/g、芝麻素含量为3.05～10.75 mg/g、芝麻林素含量为2.14～5.30 mg/g。芝麻素、芝麻林素和总酚含量与DPPH·清除能力具有显著正相关性(P<0.05),芝麻林素和总酚含量对氧化诱导时间具有极显著正相关性(P<0.01)。7个产地的黑芝麻油中，产自多哥的黑芝麻油中功能性成分含量综合得分最高，有较强的抗氧化性和氧化稳定性。     

木聚糖与芝麻油的氧化稳定性

木聚糖(lignan)类是芝麻重要的微量成分,其中的芝麻醚(Sesamolin)是芝麻酚(Sesamol)及羟基芝麻素(Sesaminol)的前驱物质,芝麻酚和羟基芝麻素是芝麻油特有的强力抗氧化物质.芝麻油的氧化稳定性也和它的特有香味一样,受到现代食品科学的注目.     

芝麻的食品科学

芝麻具有极高的食用价值。芝麻酚及羟基芝麻素是芝麻油中特有的强力抗氧化物质。芝麻的特有香味及其出色的氧化稳定性正受到近代食品科学所注目。     

冷榨芝麻油与浸出精炼芝麻油品质差异研究

通过对冷榨芝麻油和浸出精炼芝麻油样品的特征指标、质量指标、芝麻素含量、芝麻酚含量、VE含量及氧化诱导时间的测定,分析比较冷榨芝麻油与浸出精炼芝麻油的品质差别.结果表明:冷榨芝麻油与浸出精炼芝麻油在特征指标上的最大差别是不皂化物含量和反式脂肪酸含量,冷榨芝麻油中不皂化物含量约为浸出精炼芝麻油的2.5倍,冷榨芝麻油未检出反式脂肪酸,浸出精炼芝麻油检出反式脂肪酸,其含量为0.88％,其中反式油酸含量0.34％,反式亚油酸含量0.54％;冷榨芝麻油与浸出精炼芝麻油在质量指标上的主要差别是过氧化值,浸出精炼芝麻油的过氧化值高出冷榨芝麻油2倍多,其风味也明显逊色于冷榨芝麻油;冷榨芝麻油中芝麻素、芝麻酚及VE含量都高于浸出精炼芝麻油,冷榨芝麻油中芝麻素含量约是浸出精炼芝麻油的2.14倍,VE含量约是其3.41倍,冷榨芝麻油中芝麻酚含量约为0.2 mg/100 g,浸出精炼芝麻油中未检出芝麻酚;冷榨芝麻油与浸出精炼芝麻油氧化诱导时间差别不大.     

微波预处理对芝麻油营养品质及抗氧化能力的影响

以芝麻油中木脂素、维生素E、植物甾醇、总酚等微量营养成分含量及油脂的抗氧化能力为主要评价指标,探讨了微波预处理对芝麻油品质的影响。结果表明:在芝麻初始水分10%、微波频率2 450 MHz、微波功率1 200 W、微波时间5～9 min条件下,与直接低温压榨芝麻油相比,微波预处理能有效提高芝麻油中微量营养成分的含量,维生素E总量增加了0. 44%～3. 05%,植物甾醇含量增加了3. 58%～5. 89%;随着微波时间的延长,总酚及芝麻酚含量、1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力、铁离子还原抗氧化剂能力(FRAP)以及油脂的氧化诱导时间(IP值)均逐渐升高,并且在微波9 min时,总酚含量、DPPH值、FRAP值和IP值达到峰值,分别为低温压榨芝麻油的1. 94、2. 43、2. 13倍和1. 97倍。     

超声波辅助-HPLC测定芝麻油中木脂素含量

以超临界CO2流体萃取的芝麻油为原料,采用超声波辅助甲醇萃取法对芝麻油进行前处理,并通过高效液相色谱法测定芝麻油中木脂素含量。结果表明,芝麻素和芝麻林素色谱峰分离效果好,干扰峰少,芝麻素与芝麻林素平均加标回收率分别为99.3%、96.2%,相对标准偏差分别为0.87%、1.71%。与皂化法前处理方法相比,此方法的前处理简便快速、结果准确、灵敏度高、稳定性好,适用于芝麻油中芝麻素和芝麻林素含量的测定。     

水酶法芝麻油与其他工艺芝麻油品质差异研究

通过对芝麻油外观品质、理化特性、抗氧化成分及脂肪酸组成进行对比,研究了水酶法芝麻油与其他工艺芝麻油(热榨法芝麻油、冷榨法芝麻油、水代法芝麻油)的品质差异。结果表明:水酶法芝麻油的外观品质好,色泽浅,符合一级成品芝麻油标准;水酶法芝麻油的水分及挥发物的含量介于冷榨法芝麻油和水代法芝麻油之间,酸价、过氧化值、不皂化物含量最低;水酶法芝麻油的抗氧化成分(生育酚、芝麻素和芝麻林素)含量最高,但未检出芝麻酚;与热榨法芝麻油、冷榨法芝麻油、水代法芝麻油相比,水酶法芝麻油的饱和脂肪酸含量最高,不饱和脂肪酸含量最低。     

正相高效液相色谱法同时测定芝麻油中生育酚、芝麻素及芝麻林素含量

建立了正相高效液相色谱法同时测定芝麻油中生育酚(α-、β-、γ-、δ-生育酚)、芝麻素及芝麻林素含量的方法。样品经正庚烷溶解后,在二醇基硅胶色谱柱上以四氢呋喃-正庚烷溶液洗脱、荧光检测器分析。结果表明:芝麻素及芝麻林素荧光特性良好,样品分析在20 min内完成;方法学评价结果显示生育酚在1.0~5.0μg/m L、芝麻素及芝麻林素在0.1~5.0μg/m L范围内线性关系良好,相关系数R~2均大于0.99;生育酚、芝麻素以及芝麻林素的检出限为0.29~0.74 mg/kg,定量限为0.91~2.10 mg/kg;6种化合物加标回收率为83.47%~104.57%,相对标准偏差为0.38%~6.55%。采用该方法分析了12个芝麻香油、冷榨芝麻油、浸出成品芝麻油中生育酚、芝麻素以及芝麻林素含量,发现芝麻油中生育酚以γ型为主,芝麻素、芝麻林素含量较高。该方法简单、灵敏度高、重复性好,可用于芝麻油中生育酚、芝麻素及芝麻林素含量的同时检测。     

HPLC测定芝麻油中木脂素类化合物含量研究

建立了HPLC同时测定芝麻油中芝麻素、芝麻林素、芝麻酚和芝麻素酚4种木脂素化合物含量的方法。首先确定了HPLC法分离和测定这4种物质的色谱条件,色谱柱为ODS-C18(250 mm×4.6 mm,5μm);检测波长:芝麻素和芝麻林素为287 nm,芝麻酚和芝麻素酚为293 nm;柱温30℃;流速0.8 mL/min,流动相为甲醇(A)和水(B)进行梯度洗脱,梯度为0 min(A,60%)→6 min(A,60%)→9 min(A,75%)→24min(A,70%)→27 min(A,60%)→32 min(A,60%)。同时比较筛选了皂化法、氧化铝柱层析法和薄层层析法3种去除脂肪类成分的前处理方法,确定薄层层析法为最有效的前处理方法。     

In vitro studies on antioxidant activity of lignans isolated from sesame cake extract

The antioxidant activity of compounds isolated from a methanolic extract of commercial sesame cake was studied using a peroxidation model and a radical‐scavenging method. Pure compounds were isolated from the extract by preparative high‐performance liquid chromatography (HPLC) and identified and confirmed as sesamol, sesamin, sesamolin, sesaminol diglucoside and sesaminol triglucoside by HPLC, infrared, nuclear magnetic resonance and mass spectrometry. When the rate of inhibition of lipid peroxidation and the superoxide radical‐scavenging power of the individual compounds were evaluated, the compounds showed antioxidant activity to different extents. The antioxidant activity of compounds by the β‐carotene‐bleaching assay followed the order sesamol > sesamolin ≥ sesamin > butylated hydroxytoluene (BHT) > sesaminol triglucoside > sesaminol diglucoside. By the thiocyanate method the inhibition of linoleic acid peroxidation shown by sesamol, sesamin, sesamolin, sesaminol triglucoside, sesaminol diglucoside and BHT at 200 mg l^?1 was 77, 60, 69, 32, 25 and 49% respectively. A concentration–dependent superoxide–scavenging effect was also shown by these compounds. Sesamolin had an appreciable effect at 300 and 500 mg l^?1, while the other compounds were more effective at 100 mg l^?1. The study also established the occurrence of sesamol in the methanolic extract of defatted sesame cake for the first time. Copyright © 2005 Society of Chemical Industry     

Effects of roasting conditions of sesame seeds on the oxidative stability of pressed oil during thermal oxidation

Oxidative stability of sesame oil (SO) prepared from sesame seeds roasted at 213, 230, and 247 °C for each 14, 21, or 28 min was determined at 180 °C heating condition by 2,2-diphenyl-1-picrylhydrazyl (DPPH), conjugated dienoic acid (CDA) value, headspace oxygen analysis, and profile changes of sesamol and sesamolin. As sesame seeds were roasted with longer time and higher temperature, more sesamol was found in SO. SO from sesame seeds roasted at 247 °C for 28 min had the highest oxidative stability based on the results of CDA and headspace oxygen. Absorbance of DPPH from SO roasted at 230 and 247 °C showed different patterns compared to those from SO at 213 °C during thermal oxidation. Sesamol was continuously generated with the decrease of sesamolin in SO from 230 to 247 °C while sesamol in SO from 213 °C did not increase during 180 °C heating. Higher oxidative stability of SO may be related with the continuous generation of sesamol from the degradation of sesamolin during thermal oxidation rather than the initial antioxidant content.     

Effect of Infrared Heating on the Formation of Sesamol and Quality of Defatted Flours from Sesamum indicum L.

ABSTRACT:  Infrared (IR) heating offers several advantages over conventional heating in terms of heat transfer efficiency, compactness of equipment, and quality of the products. Roasting of sesame seeds degrades the lignan sesamolin to sesamol, which increases the oxidative stability of sesame oil synergistically with tocopherols. IR (near infrared, 1.1 to 1.3 μm, 6 kW power) roasting conditions were optimized for the conversion of sesamolin to sesamol. The resultant oil was evaluated for sesamol and tocopherol content as well as oxidative stability. The defatted flours were evaluated for their nutritional content and functionality. IR roasting of sesame seeds at 200 °C for 30 min increased the efficiency of conversion of sesamolin to sesamol (51% to 82%) compared to conventional heating. The γ-tocopherol content decreased by 17% and 25% in oils treated at 200 and 220 °C for 30 min, respectively. There were no significant differences in the tocopherol content and oxidative stability of the oil. Methionine and cysteine content of the flours remained unchanged due to roasting. The functional properties of defatted flours obtained from either IR roasted or conventionally roasted sesame seeds remained the same.
Practical Applications: Sesame oil is stable to oxidation compared to other vegetable oils. This stability can be attributed to the presence of tocopherols and the formation of sesamol, the thermal degradation product of sesamolin—a lignan present in sesame. Roasting of sesame seeds before oil extraction increases sesamol content which is a more potent antioxidant than the parent molecule. The conversion efficiency of sesamolin to sesamol is increased by 31% by infrared roasting of seeds compared to electric drum roasting. This can be used industrially to obtain roasted oil with greater oxidative stability.     

霞草提取物的抗氧化活性研究

采用1:1(V/V)的氯仿:甲醇溶剂,利用索氏提取器提取霞草成分,然后分别用石油醚、乙酸乙酯和正丁醇依次进行萃取,利用DPPH法、Marklund、邻二氮菲-Fe2+氧化法及磷钼络合物法测定各提取物抗氧化活性。同时与合成抗氧化剂BHT进行对照。结果表明:乙酸乙酯提取物具有最强的清除DPPH自由基和还原的能力(p<0.05)。实验所测浓度下,其清除DPPH自由基能力比同浓度的BHT强,其还原能力与BHT相当;石油醚萃取物具有最强的清除羟自由基和过氧自由基能力(p<0.05),实验所测浓度下,均比同浓度的BHT强。     

不同工艺芝麻油的品质研究

分析了热榨芝麻油、冷榨芝麻油、水代法芝麻油及精炼芝麻油的酸值、过氧化值、脂肪酸组成,以及VE、芝麻素、芝麻林素、苯并(a)芘含量。结果表明:热榨芝麻油的酸值最高,冷榨芝麻油的酸值最低,精炼芝麻油的过氧化值最高,冷榨芝麻油的过氧化值最低;热榨芝麻油的反式脂肪酸含量高,冷榨芝麻油中未检出反式脂肪酸;冷榨芝麻油的V_E含量是热榨芝麻油的1.12倍,是水代法芝麻油的1.17倍;热榨芝麻油与精炼芝麻油的苯并(a)芘含量均为冷榨芝麻油的2.9倍。冷榨芝麻油品质较好。     

Effect of refining on the lignan content and oxidative stability of oil pressed from roasted sesame seed

Oxidative stability of pressed and refined sesame oils during seven consecutive months of storage at room temperature was studied comparatively. Lignans, peroxide value (PV), p‐anisidine value (AV) and total oxidation value (TOTOX) were determined as evaluation indices. PV, AV and TOTOX of sunflower, corn and peanut oils were simultaneously monitored to compare their oxidative storage stabilities with the sesame oils. The total amount of lignans in the pressed and refined sesame oils were 1103 and 790 mg per 100 g respectively. The contents of sesamin and sesemolin in the pressed sesame oil were 734 and 369 mg per 100 g respectively. Sesamin and sesamolin content were reduced by 256 and 159 mg per 100 g, respectively, after refining. Nearly 40% of the sesamin epimerised to asarinin after oil refining. The results indicate that sesame oils pressed from roasted seed have far superior storage stability to oxidation than the other vegetable oils. This difference may be due to much higher sesamin and sesamolin contents in the pressed sesame oils. The results suggest lignan compositions and levels could be used as key indicators for evaluating the oxidative storage stability of sesame oil products as well as to differentiate between pressed and refined sesame oils.     

Anti-radical activity and oxidative stability of oils manufactured from flax, sesame and silybum seeds

Comparative analysis of oils, prepared from flax, sesame and silybum seed composition, and adequate oil blends, prepared by mixing flax oil, sesame oil and silybum oil was performed. Antiradical activity was evaluated for the oils, both for their methanol-soluble phase and the fraction insoluble in methanol. DPPH radical scavenging activity expressed in Trolox equivalent antioxidant capacity. Oxidative stability during 6-month store was evaluated by peroxide value and dienic conjugates content. Oils from seed composition show the more high antiradical activity and oxidative stability than adequate oil blends. A significant correlation was found between antiradical activity and gamma-/alpha-tocopherol ratio in oils.     

裂殖弧菌DHA油脂纯化后的氧化稳定性

对裂殖弧菌DHA油脂进行纯化,研究其氧化稳定性的变化。DHA油脂经多层填料层析柱纯化后,分析纯化前后DHA油脂的脂肪酸组成及微组分的含量变化,并对其甲醇萃取物进行DPPH自由基清除能力的评价。纯化前后的DHA油脂采用光照和Schaal烘箱法进行加速氧化,以过氧化值(POV,一级氧化指标)和硫代巴比妥酸反应物(TBARS,二级氧化指标)表征油脂氧化情况。结果表明：DHA油脂经纯化去除微组分后,其甲醇萃取物清除 DPPH自由基的能力以及对光、对热的稳定性均显著降低。     

Antioxidative activity of the crude extract of lignan glycosides from unroasted Burma black sesame meal

Sesame seed contains lignans and lignan glycosides. The antioxidative activity of the crude extract of lignan glycosides obtained from unroasted defatted black sesame seeds was investigated in this study. The components responsible for the antioxidative activity were also studied. The unroasted black sesame seeds, after defatted with n-hexane, were extracted with 80% methanolic solution to prepare for the crude extract of lignan glycosides. After chromatographic separation of this crude extract with octadecylsilane (ODS) column (2.5 cm i.d.×100 cm), four fractions (Fr1, Fr2, Fr3, Fr4) of the crude extract were obtained from the eluents of 25, 50, 75% aqueous methanolic solution and 100% methanol, respectively. Among them, Fr2 and Fr3 showed better antioxidative activity by 2,2-Diphenyl-1-picrylhydrazyl hydrate (DPPH) antioxidative assay. These two fractions were further purified by preparative HPLC (Hyperprep 100 C18 column; 20 mm i.d.×250 mm) and the main constituents were found to be lignan glycosides and some unknown brown materials. It was interesting to find that the brown materials (in Fr2) exhibited exceptional DPPH free radical scavenging effect, whereas the identified sesaminol triglucoside in Fr2 and sesaminol diglucoside in Fr3 possess no such activity. Using Cu⁺²-induced oxidation of human low-density lipoprotein (LDL) for the antioxidative assay, similar results were observed. Seaminol triglucoside and sesaminol diglucoside showed no effect on the extension of lag phase, while the brown materials had excellent inhibitory effect on the oxidation of LDL. Furthermore, natural antioxidants such as γ-tocopherol, sesamol and sesaminol were not detected in the crude extract of lignan glycosides. Our findings suggest that the brown materials present in Fr2 had a significant contribution to the antioxidative activity of the crude extract of lignan glycosides. Identification of the responsible components is underway.     

Sesame lignans enhance the thermal stability of edible vegetable oils

The effect of sesame lignans on the thermal and storage stability of edible vegetable oils (soybean-SBO, sunflower-SFO and ricebran-RBO) was studied by (i) determining the total free radical scavenging activity (RSA) using DPPH, (ii) % total tocol retention, (iii) lignan profile and (iv) PUFA composition. The order of RSA and retention of total tocols of oils heated up to 120 min at frying temperature (FT) were RBO = SBO > SFO and RBO > SBO > SFO, respectively. Heating SBO or SFO at FT after addition of 1.2% lignans increased RSA of SBO to a greater extent than that of SFO, and increased retention of total tocols only in SBO. However, addition of lignans did not further increase the RSA of RBO. Heating oils with added lignans, increased sesamol and decreased sesamolin while sesamin was relatively resistant to heat. These findings suggest that sesame lignans may have potential application as natural antioxidants in the edible oil and food industry.