大豆油脱臭馏出物的酶法甲酯化

采用脂肪酶催化大豆油脱臭馏出物(SODD)中的脂肪酸进行甲酯化反应。对反应条件进行单因素试验,确定了最佳反应工艺参数。经分析初步得出脂肪酶催化法甲酯化最佳条件为:甲酯化温度45℃,甲酯化时间16h,转速180r/min,底物比0.1:1。最佳条件下脂肪酸甲酯化率达到96.2%。脂肪酶反复使用6个批次活性无明显降低。     

超声波在憎水性黑米色素制备中的应用

在超声波作用下,采用乙酸酐酯化处理水溶性黑米色素,制备了憎水性黑米色素.探讨了超声水浴温度、反应时间、黑米色素与乙酸酐料液比等因素对黑米色素酯化度、色价的影响.结果表明:采用料液比2 g∶10 mL、在70℃超声水浴中反应3 h,为制备憎水性黑米色素的最优条件.同时通过红外光谱、可见吸收光谱及溶解性对黑米色素的酯化进行了初步探讨.     

半纤维素酯化和醚化改性研究进展

近些年,从可再生资源获得新的功能性材料引起了广泛关注。半纤维素通过改性后可替代传统化石材料制备新型功能材料。从酯化和醚化两方面论述半纤维素化学改性的研究现状,并对半纤维素改性应用前景进行展望。半纤维素酰氯酯化赋予半纤维素斥水性能而酸酐酯化赋予亲水性能,羧甲基化、甲基化、季碱化和苄基化在半纤维素醚化方面取得很大进展。新的技术应用将会更大程度提高改性半纤维素取代度,为发掘其鲜为人知的用途提供了新窗口。     

Utilization and metabolism of palmityl and oleoyl fatty acids and alcohols in caecal enterocytes of Atlantic salmon (Salmo salar L.)

The substitution of fish oil with wax ester‐rich calanoid copepod‐derived oil in diets for carnivorous fish, such as Atlantic salmon, has previously indicated lower lipid digestibility. This suggests that the fatty alcohols (FAlc) present in wax esters may be a poorer substrate for intestinal enzymes than the fatty acids (FA) in triacylglycerol (TAG), the major lipid in fish oil. The hypothesis tested was that the possible lower utilization of dietary FAlc by salmon enterocytes is at the level of uptake and that subsequent intracellular metabolism was identical to that of FA. A dual‐labelled FAlc–FA metabolism assay was employed to determine simultaneous FAlc and FA uptake and relative utilization in enterocytes isolated from pyloric caeca of Atlantic salmon fed either a diet supplemented with fish oil or wax ester‐rich Calanus oil. The diets were fed for 10 weeks before caecal enterocytes from each dietary group were isolated and incubated with equimolar mixtures of either [1‐¹⁴C]16:0 FA and [9,10(n)‐³H]16:0 FAlc, or [1‐¹⁴C]18:1n‐9 FA and [9,10(n)‐³H] 18:1n‐9 FAlc. Uptake was measured after 2 h with relative utilization of labelled FAlc and FA calculated as a percentage of uptakes. Differences in uptake were observed, with FA showing higher uptake than FAlc, and 18:1 chains a higher uptake than 16:0. A proportion of unesterified FAlc was possibly recovered in the cells, but the majority of FAlc was recovered in lipid classes such as TAG and phospholipids indicating substantial conversion of FAlc to FA followed by esterification. However, incorporation of FA and FAlc into esterified lipids was higher when derived from FA than from FAlc. Twenty‐five to fifty percentage of the absorbed 16:0 FA was recovered in TAG fraction of the enterocytes compared with 15–75% of 18:1 FA. Twenty to thirty percentage of the absorbed 16:0 FA was recovered in the phosphatidylcholine fraction of the enterocytes compared with only 5–15% of the 18:1 FA. Less than 15% of the fatty chains taken up by the cells were used for energy production, with significantly higher oxidation of 18:1 in enterocytes from fish fed the fish oil diet compared with the Calanus oil diet. However, overall, dietary copepod oil had little effect on FAlc and FA metabolism. Metabolic modification by elongation and/or desaturation was generally low at 1–5% of the uptake. We conclude that our hypothesis was generally proved in that the uptake of FAlc by salmon enterocytes was lower than the uptake of FA and that subsequent intracellular metabolism of FAlc was similar to that of FA. However, unesterified FAlc was possibly recovered in the cells suggesting that the conversion to FA may not be concomitant with uptake.     

基于BP神经网络的脂肪酶酯化菜籽油脱臭馏出物的仿真研究

该文采用BP神经网络对脂肪酶催化酯化菜籽油脱臭馏出物的工艺条件进行了仿真研究。将中心组合试验和神经网络相结合,采用动量梯度下降法对网络进行训练仿真,并利用训练好的网络对催化酯化工艺条件进行预测。结果表明：经过训练的网络可以很好的模拟反应条件,得到了脂肪酶催化反应的最佳工艺参数,此时脂肪酸甲酯的含量为55.2%,维生素E保留率达到90%,为脱臭馏出物的酯化催化效果的预测提供了一条可行的途径。     

碳基固体酸催化生物油酯化降酸工艺参数优化

为了降低生物油中羧酸类物质的质量分数,提高生物油品质,本试验采用碳基固体酸作为催化剂,对生物油进行催化酯化降酸提质。以乙酸为模型与甲醇反应,用单因素和响应面法优化生物油催化酯化反应条件,得出最佳工艺参数:反应温度100℃、醇酸比3.37、反应时间2.49 h、催化剂质量分数为5.26%,乙酸平均转化率为94.72%,在此条件下,分别用甲醇、乙醇、正丁醇与生物油进行催化酯化反应。结果表明:酯化后生物油中羧酸类物质转化成酯,酸值降低了82.82%~91.41%,降酸效果明显。且酯化后,生物油的密度降低、黏度减小、热值增加,提高了生物油作为燃料的品质。本研究可为生物油降酸提质提供参考依据。     

菜籽油脱臭馏出物中甾醇分离的甲酯化过程优化研究

运用中心组合设计,以甾醇得率与纯度为考察指标,对菜籽油脱臭馏出物的甲酯化过程工艺进行了优化研究。通过甾醇回收率的响应曲面分析,考察了甲酯化时间、催化剂浓硫酸量与甲醇/物料比及其交互作用的影响,并建立了其数学回归模型,利用Matlab绘制出响应曲面图,揭示了内在关系。结果表明：甲酯化温度60℃,甲醇/物料比100 mL/(100 g),甲酯化时间1.65 h,催化剂浓硫酸加量4.4%,将甲酯化产物通过结晶与冷冻高速离心,甾醇得到较高纯度与得率,维生素E也得到较好保留。二次重结晶甾醇纯度可以达到95％以上,总得率达到45％以上。     

高酸值米糠油酯化脱酸成生物柴油原料

为充分利用高酸值米糠毛油,将其脱酸成生物柴油原料。采用酯化脱酸方法,通过对多种酯化脱酸催化剂的比较,结果表明氧化锌具有较强的催化活性。氧化锌作为米糠油酯化脱酸的催化剂,分别考察了甘油添加量、催化剂添加量、反应温度、反应时间对酯化脱酸的影响。得到了以下较优工艺参数：真空度为0.1 MPa,甘油添加量为理论甘油量1.044 g,催化剂添加量为油质量的0.1%,反应温度200℃,反应时间6 h。在此优化条件下,米糠油的酸值从38.14 mg/g降至5.17 mg/g,满足了作为生物柴油生产原料的要求。     

魔芋葡甘聚糖酯化改性产物对空气中SO2吸附及抑菌效果研究

以魔芋葡甘聚糖为原料,分别采用苯甲酸、醋酸和没食子酸对魔芋葡甘聚糖进行酯化改性,研究了改性pH值、温度及改性处理时间对改性产物吸附空气中SO2和抑菌效果的影响,优化了改性工艺参数,得到了有较好使用效果的天然的有机大分子空气净化材料.研究结果表明:当采用苯甲酸为魔芋葡甘聚糖酯化改性剂时,改性产物对空气中的SO2吸附效果和抑菌作用效果优于使用醋酸和没食子酸的改性产物.其改性处理温度50℃,反应时间2 h,pH值3,改性反应产物对空气中SO2的吸附率可达98.7%,抑菌率可达到86.3%.     

纳米固体超强酸催化合成苯乙酮酸冰片酯的研究

以纳米固体超强酸为催化剂合成苯乙酮酸冰片酯,在比较了不同的温度、酸醇比、反应时间对该反应酯化率的影响后,确定了在此催化剂存在的条件下,酸醇比为1∶6时,温度为90℃的条件下反应2 h,得到其酯化率最高达78.5%。