烷醇酰胺复合物的制备

将甘油三酸酯、十二碳脂肪酸混合后与不同摩尔分数的醇胺制备成各类烷醇酰胺复合物,测定其基本性能,同时考察其对坯革的加脂性能.结果表明,甘油三酸酯、十二碳脂肪酸混合后与长链烷基胺制备的烷醇酰胺复合物流动性能良好、易乳化、黏度低、乳液稳定;加脂后坯革机械性能优良(撕裂强度为17.062 N/ram、抗张强度为6.039 N/...     

响应曲面法优化母乳化结构油脂制备工艺

文中对母乳化结构油脂的制备工艺进行优化。选用Sn-2位富含棕榈酸的猪油为原料,以Sn-1,3专一性脂肪酶Lipozyme RM IM作催化剂,与游离脂肪酸进行酶促酯交换反应制备母乳化结构油脂。通过单因素试验和响应面法优化工艺参数,建立了合成产物中Sn-2棕榈酸分布与反应温度、底物比酰基供体与猪油摩尔比、反应时间、加酶量之间的二次回归模型,即Y=-2 304.15+63.75 A+129.27 B+158.19C+45.85D-0.28AB-1.21AC-0.12AD-6.02BC-0.36BD+3.62CD-0.50A2-24.64 B2-52.00C2-2.05D2。优化后的工艺条件为:反应温度60.42°C;底物酰基供体与猪油的摩尔比为2.08∶1;反应时间1.05 h,酶/底物10.15%,制得的结构油脂中棕榈酸含量为20.35%,其中71.68%位于Sn-2位,与母乳脂肪的结构基本一致。表明采用RSM优化得到的酶促酯交换工艺条件参数适合以猪油为原料,制备母乳化结构油脂,建立的模型可以进行准确可靠的预测。     

Combined nonenzymatic-enzymatic method for the synthesis of simple alkyl fatty acid esters from soapstock

Soapstock (SS) is a by-product of the extraction of oilseeds to produce edible oils. Annual U.S. production exceeds one-half million tons. A representative sample of SS consists of 45.1% water, 10.0% free fatty acids, 10.1% triglycerides, 1.8% diglycerides, 3.6% phosphatidylethanolamine, 2.2% phosphatidylinositol, 2.7% phosphatidylcholine, 14.0% solvent-insolubles and 10.5% other material, which was not characterized. A process has been developed that sequentially employs a nonenzymatic and an enzymatic step to convert the lipid-linked and the free fatty acids of SS to the esters of monohydric alcohols. The first step of the process employed alcohol and potassium hydroxide to transesterify the glyceride-and phosphoglyceride-linked fatty acids of the substrate. Because water inhibited the reaction, it was necessary that the SS be dried before use. Nonetheless, even with some batches of SS with water contents below 1% (weight basis), ester hydrolysis accompanied esterification. Each of five examined simple primary alcohols participated effectively in the transesterification reaction, which proceeded rapidly at room temperature and was essentially complete within 1 h. The average ratio of transesterification to hydrolysis in four examined small primary alcohols was 4:1. However, in methanol this value was 99:1 due to the virtual absence of hydrolysis. Significant transesterification by a secondary alcohol (isopropanol) did not occur at room temperature. The minimum effective molar ratio of alcohol to lipid-linked fatty acids was 20:1. The minimum effective concentration of KOH was between 0.10 and 0.15N. The efficiency of the transesterification reaction exceeded 90% of theoretical maximum. The second step of the process involves lipase-mediated esterification of the free fatty acids in the preparation that are not esterified by the alkaline transesterfication. Of four lipase preparations examined (Novo Lipozyme IM 20 and SP435, and Amano PS30 and CE), only SP-435 catalyzed significant esterification of the free fatty acids. The reaction was not catalyzed by heat-denatured enzyme. In the pH range between 6 and 13.5, the enzyme reaction proceeded best at pH 6, although also well at pH 7. The optimal water concentration was 0.70% (vol/vol). At an enzyme dosage of 1.1% (weight basis, relative to the dry weight of SS present) under optimal conditions and at 42°C, 63% of the free fatty acids in a post-alcoholysis mixture were enzymatically esterified. The addition of molecular sieves did not increase esterification, which was probably retarded by the high viscosities of the reactions. Under the optimal conditions identified here, the degree of conversion of the fatty acids in SS to simple alkyl esters by the combined reaction scheme was 81%. Opportunities exist for further optimization of these reactions.     

Composition and crystallization of milk fat fractions

Milk fat was fractionated by solvent (acetone) fractionation and dry fractionation. Based on their fatty acid and acyl-carbon profiles, the fractions could be divided into three main groups: high-melting triglycerides (HMT), middle-melting triglycerides (MMT), and low-melting triglycerides (LMT). HMT fractions were enriched in long-chain fatty acids, and reduced in short-chain fatty acids and unsaturated fatty acids. The MMT fractions were enriched in long-chain fatty acids, and reduced in unsaturated fatty acids. The LMT fractions were reduced in long-chain fatty acids, and enriched in short-chain fatty acids and unsaturated fatty acids. Crystallization of these fractions was studied by differential scanning calorimetry and X-ray diffraction techniques. In this study, the stable crystal form appeared to be the β′-form for all fractions. At sufficiently low temperature (different for each fraction), the β′-form is preceded by crystallization in the metastable α-form. An important difference between the fractions is the rate of crystallization in the β′-form, which proceeds at a much lower rate for the lower-melting fat fractions than for the higher-melting fat fractions. This may be due to the much lower affinity for crystallization of the lower-melting fractions, due to the less favorable molecular geometry for packing in the β′-crystal lattice.     

分子蒸馏纯化富含中长碳链甘油三酯的人乳替代脂

酶法合成富含中长碳链甘油三酯的人乳替代脂,选用分子蒸馏技术对酯交换产物进行纯化。在进料温度65℃、冷凝器温度30℃、压力1 Pa、刮板转速120 r/min、进料速度2. 5 mL/min条件下,探究了分子蒸馏温度对重相组成的影响,确定最佳分子蒸馏温度为210℃。经过分子蒸馏后,大部分的甘油二酯及游离脂肪酸被去除,产品中甘油三酯含量可达97. 22%,甘油三酯中MLCT含量增加到74. 82%。     

超高效合相色谱串联四级杆飞行时间质谱快速分析植物油的甘油三酯组成

采用超高效合相色谱串联四级杆飞行时间质谱(UPC~2-Q-TOF-MS)技术分析了11种植物油的甘油三酯组成。这些植物油中,O-L-L为葵花籽油(22. 27%±1. 87%)、菜籽油(21. 07%±1. 76%)、玉米油(19. 84%±1. 35%)、米糠油(19. 37%±0. 87%)、芝麻油(17. 55%±0. 82%)中含量最高的甘油三酯; O-O-O在花生油(18. 25%±0. 69%)和橄榄油(39. 37%±0. 10%)中的含量最高;大豆油中含量最高的甘油三酯是L-L-L(22. 16%±1. 71%),亚麻籽油中是O-Ln-Ln(21. 85%±0. 18%),稻米油中是O-L-P (18. 58%±1. 02%),以及棕榈油中是O-P-P(25. 05%±0. 73%)。O-O-L与S-L-L等ECN值相同的甘油三酯实现了分离,且含量微少的甘油三酯组成也得到了鉴定。     

Solid immiscibility in milk fat fractions and methods to determine their occurrence

In this work, the occurrence of solid phase immiscibility during the fractionation process of milk fat is documented. It is shown that solid phase immiscibility occurs in normal fractionation procedures, upon crystallisation at low temperatures and in particular on further fractionation of narrow melting fractions. This phenomenon results in distinct phases of crystallisation. In some cases, the initial phase yields intermediate solid levels independent of increasing supersaturation. The subsequent increase of solids content is solely a contribution of a second, independent crystallisation event. Furthermore, it could be shown that the induction time for the second crystallisation event is not influenced by the presence or absence of the first triacylglyceride group. These results clearly indicate the independence of the crystallisation of the different immiscible fractions in terms of kinetics and thermodynamics. The different processes during the crystallisation process are monitored simply by viscosimetry.     

一种快速评价煎炸油稳定性方法的建立

用于评价煎炸油稳定性的传统方法不能如实反映实际煎炸过程中的变化,为了快速可靠地模拟实际煎炸过程中油脂的劣变情况,将以淀粉、葡萄糖、硅胶(质量比4∶1∶1)为原料制备的配方食物加入(180±5)℃的大豆油中,在自制快速煎炸装置中以500 r/min的搅拌速度进行煎炸试验,测定煎炸油极性物质含量的变化。通过分析快速煎炸和实际煎炸中极性物质的含量及其组成变化,确立两者之间的联系。结果表明,所建立的快速煎炸方法操作简便、耗时短,与实际煎炸中油脂劣变程度有良好的一致性,可应用于快速评估煎炸体系中油脂的稳定性。     

臭氧氧化蓖麻油制备甘油三酸酯多元酸的研究

以蓖麻油为原料,经臭氧氧化法制备甘油三酸酯多元酸.考察了溶剂、臭氧化反应温度及时间,氧化裂解温度及时间对反应的影响.实验结果表明,合成甘油三酸酯多元酸的最佳条件为:m(蓖麻油):m(乙酸) 为1:4,臭氧化反应温度10～15 ℃,时间2 h;氧化裂解温度90～95 ℃,时间2.5 h.在此条件下收率达83%以上.     

Mechanisms of dyslipidemia of chronic renal failure

Chronic renal failure is associated with profound dysregulation of lipid metabolism and marked abnormalities of plasma lipid profile. This review is intended to provide an overview of the molecular basis of lipid disorders in chronic renal failure and explore their potential impact on cardiovascular disease and energy metabolism.