共查询到18条相似文献,搜索用时 62 毫秒
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以大豆甾醇和油酸为原料,在酶的催化下合成大豆甾醇油酸酯,采用高效液相色谱对产物进行定性定量分析,通过单因素实验考察催化剂脂肪酶的种类和用量、醇酸摩尔比、反应温度和反应时间等对大豆甾醇油酸酯产率的影响,并通过正交实验优化大豆甾醇油酸酯的合成工艺条件。采用红外光谱对产物进行了表征。结果表明:大豆甾醇油酸酯的最佳合成工艺条件为催化剂N435脂肪酶用量6%(以大豆甾醇和油酸的总质量计)、醇酸摩尔比1∶1、反应温度50℃、反应时间30 h、异辛烷用量10 mL(大豆甾醇为1 mmol时),在最佳条件下大豆甾醇油酸酯产率为86. 51%;红外表征说明合成的产物为大豆甾醇油酸酯。 相似文献
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本文探讨了一缩二乙醇油酸双酯酯化反应的合成原理及其工艺操作方法。采用正交试验法,考察了反应温度、反应时间、原料配比和催化剂用量等反应条件的影响,确定了最佳合成条件。皮革加脂试验结果表明,一缩二乙二醇油酸双酯加脂效果优良。 相似文献
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固体超强酸Nafion-H催化合成植物甾醇油酸酯 总被引:1,自引:1,他引:0
以固体超强酸Nafion–H为催化剂,植物甾醇与油酸直接酯化的方法合成植物甾醇油酸酯。考察了催化剂用量、原料比等因素对酯化反应产物的影响。正交实验优化结果表明,醇酸摩尔比为1∶1.3,催化剂用量为2.5%(植物甾醇质量),反应温度140℃,反应时间9 h,是合成植物甾醇油酸酯的优化工艺条件,在此条件下反应的酯化率为95.8%。产品植物甾醇油酸酯通过分子蒸馏提纯后纯度可达98.2%。该合成污染小,催化剂无需处理即可重复再次使用,具有良好的应用前景。 相似文献
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《食品工业》2016,(10)
利用新型催化剂固体超强酸SO_4~(2-)/TiO_2合成了维生素E亚油酸酯,研究了反应物配比(X_1)、反应温度(X_2)、催化剂用量(X_3)、反应时间(X_4)等因素对维生素E亚油酸酯产率的影响,利用Box-Benhnken中心组合试验和响应面分析法,进行工艺优化,并将维生素E亚油酸酯应用于食用油中。结果表明,维生素E亚油酸酯产率预测模型:Y_1=-301.198+35.634 62X_1+12.958 27X_2+6.625X_3-5.855 769X_1~2-0.137 231X_2~2。最优工艺条件为:亚油酸酰氯与维生素E摩尔比3︰1、反应温度45℃、SO_4~(2-)/TiO_2用量4.5%、反应时间3.5 h。此时产率达到95.6%。食用油抗氧化性研究表明维生素E亚油酸酯有较好的抗氧化性能,可以作为化学抗氧化剂替代品。 相似文献
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The safety of large doses of vitamin E went virtually unquestioned until the early 2000s, when several studies were published showing that consumption of vitamin E from dietary supplements increased mortality, as well as the risk of gastrointestinal cancer and heart failure. These studies prompted numerous letters to the editors of medical journals and widespread coverage in the media. Both the medical community and the general public became confused and concerned about the use of vitamin E supplements. The purpose of this article is to review the medical literature and to explain these unusual findings. First we provide an overview of the earlier literature on vitamin E. Second, we provide a critical assessment of three meta-analyses that were neutral or negative toward vitamin E supplementation. Third, we review the limitations of meta-analyses in general. Fourth, we assess the individual studies that comprised one of the three meta-analyses. Since all three meta-analyses used many of the same studies, the individual critique should further the understanding of the limitations of these meta-analyses, and the meta-analysis approach in general. Lastly, we offer some guidance for healthcare professionals to give to the general, healthy public and those with chronic conditions who are no doubt left puzzled as to what to do regarding vitamin E supplementation. 相似文献
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维生素E酯衍生物稳定性能及其在食品中的应用研究 总被引:3,自引:1,他引:3
为了研究维生素E酯衍生物的稳定性能及其应用注意事项,本文探讨了水分、温度、pH值、脂肪酶、血清等因素对维生素E醋酸酯化学稳定的影响,并比较了游离维生索E与维生素E醋酸酯在油脂抗氧化性能方而的区别。结果表明维生素E乙酸酯在较低温度含水溶液中基本不解离;在较高温的酸性或碱性含有水条件下,维生素E乙酸酯有一定程度的解离;而在含有脂肪酶的体系中,维生素E乙酸酯十分容易解离。维生素E乙酸酯和游离的维生素E的生理活性基本相同,但是在化学稳定性和抗氧化性能方面有着明显的区别。为了提高维生素E的使用效率,在食品或保健品的生产过程中,应根据生产或产品的实际需要添加适当形式的维生素E。 相似文献
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The aim was to determine if vitamins E and C inhibit the release of cortisol from bovine adrenocortical cells when stimulated with ACTH in vitro. A factorial arrangement of treatments was used to culture bovine adrenocortical cells with different concentrations of vitamins E and C [(+)-α-tocopherol at 0, 2.3, and 16 μM and l-ascorbic acid at 0, 15, and 50 μM]. After 3 and 7 d of vitamin treatments, cell cultures were stimulated with ACTH (1 nM) for 24 h and the culture medium extracted to measure cortisol released by the cells using HPLC with UV detection. Vitamin E, vitamin C, or their combination did not affect the amount of cortisol released by the adrenal cultures to the media. Cortisol released by the adrenal cultures ranged from 33.6 ± 6.85 to 49.7 ± 8.01 nmol per 107 cells. The modulation effect of vitamins E and C on the stress response does not take place at the cortex of the adrenal gland. 相似文献
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Contents and retentions of selected vitamins in broiled and grilled bison patties from four producers were determined. Mean vitamin contents of uncooked bison patties were (per 100 g wet weight): 0.038 mg thiamin, 0.220 mg vitamin B-6, 1.457μg vitamin B-12, and 0.286 mg vitamin E; no differences were observed among producers. Differences were found (P<0.05) among producers for vitamins B-6, B-12, and E (broiled only), but not for thiamin contents of cooked bison patties. The mean retention values in cooked patties were: 68.9% thiamin; 67.5% vitamin B-6; 67.0% vitamin B-12; and 76.1% vitamin E. Bison patties are rich sources of vitamin B-12 and good sources of vitamin B-6. 相似文献