油酸糖酯的酶法合成及表面性能测定

摘要以油酸和糖（麦芽糖、葡萄糖、山梨醇和木糖醇）为原料，在脂肪酶（Novzyme435）的催化下，合成了4种油酸糖酯。通过IR和Ms对产品进行了表征。对所合成的油酸糖酯进行了表面性能（CMC、表面张力、HLB值，乳化性和乳化稳定性）测定。试验结果表明油酸：糖为（1-1．5）：1（物质的量比），脂肪酶用量为0．30～0．36g／mol油酸，溶剂（丙酮）用量为10～20mL／mol油酸，回流反应42～72h，油酸的转化率为89％-95％。IR显示产品为酯，MS显示产品分别为：油酸麦芽糖酯，油酸葡萄糖酯，油酸山梨醇酯，油酸木糖醇酯。4种油酸糖酯都具有良好的表面活性，其临界胶束浓度为（CMC）7．94×10-43．98×10^-5mol·L-1；HLB值6．8—13．0，它们都具有很好的乳化性能，可用作O／W和W／O型乳化剂。

硅胶柱色谱和反相高效液相色谱结合分离制备亚油酸海藻糖单酯

采用固定化脂肪酶作生物催化剂在叔丁醇体系中成功的合成了亚油酸海藻糖单酯。通过硅胶柱色谱和反相高效液相色谱(RPLC)相结合的方法,得到了高纯度的亚油酸海藻糖单酯样品。将洗脱液经过旋转蒸发浓缩、冷冻干燥后,得到白色晶体,用电喷雾电离质谱(ESI-MS)和核磁共振氢谱(1HNMR)以及碳谱(13CNMR)对目标产物进行了确认,鉴定为亚油酸海藻糖单酯。该法具有制备量大和分离效率高的特点。

非水相酶法合成亚油酸海藻糖单酯工艺的研究

在叔丁醇中,以亚油酸和海藻糖为原料,通过固定化脂肪酶Novozym 435催化合成了亚油酸海藻糖单酯。通过中心组合设计及响应面分析,确定酯化反应的最佳合成工艺为:海藻糖浓度13.2 mmol/L,亚油酸浓度41.7 mmol/L,分子筛3.1 g,脂肪酶0.3 g,叔丁醇20 mL,50℃、150 r/min恒温水浴振荡器反应50.4 h,亚油酸海藻糖单酯的转化率达到74.5%。

二步法合成失水木糖醇油酸酯

本文采用二步合成法合成了失水木糖醇油酸酯。讨论了酯化阶段催化剂种类、催化剂用量、醇酸摩尔比、反应时间对产品酸值的影响,结果表明在酯化阶段使用2%NaOH反应4小时,醇酸摩尔比1.3:1时可以得到合格的产品。同时测定了产品的皂化值和HLB值。

魔芋葡甘聚糖及其油酸酯化物的体外抗氧化初步研究

对魔芋葡甘聚糖(KGM)和魔芋葡甘聚糖油酸酯(KGM酯)体外抗氧化性进行了研究。通过氧化诱导试验、清除DPPH自由基、清除ABTS自由基、对Fe^(2+)螯合能力、还原能力试验发现:KGM和KGM酯均有一定的抗氧化性,酯化度越高,抗氧化能力越强;当菜籽油中KGM和酯化度最高的KGM酯1添加量为0.8%时,与空白对照相比其氧化诱导时间分别延长5.94 h和2.56 h;在KGM酯与茶多酚、V_C、TBHQ协同试验中,KGM酯也表现出一定抗氧化性;质量浓度为0.5 mg/m L时,KGM和KGM酯1对DPPH自由基清除率分别为61.68%和36.93%;质量浓度为2.0 mg/m L时,KGM和KGM酯1对ABTS自由基清除率分别为20.31%和17.26%,对Fe^(2+)螯合率分别为17.58%和9.79%。虽然KGM酯化后其抗氧化能力稍有减弱,但仍具有抗氧化性,且与酯化程度呈正相关。

超声辅助酶法合成魔芋葡甘聚糖油酸酯研究

研究了超声辅助酶法合成魔芋葡甘聚糖油酸酯的工艺条件。以酯化率为评价指标,系统研究了超声频率、超声功率、反应温度、反应时间、反应介质初始水分活度、酶与底物浓度比对超声辅助酶法合成魔芋葡甘聚糖油酸酯的影响,并在此基础上进行了L_(18)(3~7)正交实验优化合成工艺。结果表明,最佳工艺条件为:超声频率20 k Hz,超声功率220 W,反应温度50℃,反应时间8 h,反应介质初始水分活度0.65,酶与底物浓度比1∶1。在最佳条件下酯化率达到83.40%。与无超声辅助酶催化工艺相比,反应时间8 h,酯化率由9.48%提高到83.40%,超声对提高酯化反应作用显著。

Effects of Na2S2O3 and Glucose on the Compositions of Glycerolipids and Their Fatty Acids in Synechocystis sp. PCC 6803 Cells

Compositions of glycerolipids and fatty acid compositions of glycerolipids were compared among Synechocystis sp. PCC 6803 cells grown in the BG-11 medium containing different concentrations of glucose and Na2S2O3 in this study. It was found that Na2S2O3 can effectively increase the percentage of sulphoquinovosyl diacylglycerol (SQDG) and phosphatidylglycerol (PG) to total membrane lipids and the simultaneous application of glucose with Na2S2O3 can counteract the effect of Na2S2O3. In addition, Na2S2O3 can significantly increase the percentage of palmitic acid (C, 16:0) in fatty acid composition of monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG) and decrease the fatty acid unsaturation degree accordingly, and these effects can also be eliminated by glucose. These results indicate that Na2S2O3 can take as a reductant to make membrane lipids in a low unsaturated state, and the simultaneous application of glucose can decrease the reducing power of Na2S2O3. In addition, Na2S2O3 can take as a sulfur donor for the synthesis of SQDG.

COMPARISON OF ENERGY RESERVES AND UTILIZATION IN LIPOSCELIS BOSTRYCHOPHILA POPULATIONS SELECTED FOR TOLERANCE TO CONTROLLED ATMOSPHERE

One population of Liposcelis bostrychophila Badonnel (CA selected) was exposed to a controlled atmosphere(CA) (35% CO 2+1% O 2, balance N 2) for 30 generations. Another population (control) was reared under natural atmospheric conditions. Reserves of triacylglycerol, polysaccharides and free amino acids were evaluated in adults of the CA selected and the control populations in generations F 15 and F 30 The utilization rate of triacylglycerol and polysaccharides in the CA exposure were also determined in generation F 30. The results indicate that the reserves of triacylglycerol and polysaccharides increased significantly during selection for CA tolerance; the higher the tolerance level, the greater the reserves. A total of 15 free amino acids constituents were detected in both populations. The total amino acid content in the CA selected population was obviously higher than that in the control population. Exposure of this population to a controlled atmosphere was associated with a steady utilization of reserves. In contrast, the unselected population responded to the controlled atmosphere by accelerated utilization of triacylglycerol and polysachharides. Comparison of utilization rates during CA exposure showed that triacylglycerol is the main energy source, and polysaccharides contribute only a small extent to the metabolic energy supply.