葡萄糖水溶液乳化柴油制备工艺参数优化

为了研究葡萄糖作为柴油替代燃料的稳定性和燃油经济性,该文基于稳定性试验数据建立响应面模型,并对葡萄糖水溶液乳化柴油(简称葡萄糖乳化柴油)进行配比优化和试验验证。根据亲油-亲水平衡(hydrophilic and lipophilic balance,HLB)理论和乳化原理,选择制备参数和确定取值范围,得出:HLB值范围5~6.5、复配乳化剂由Span80和Tween80组成、助溶剂为蓖麻油、葡萄糖水溶液体积分数10%~25%和溶液中葡萄糖质量分数10%~25%。根据稳定性试验数据建立响应面模型,并对葡萄糖乳化柴油的配方进行理论优化和试验验证,得到最优的葡萄糖乳化柴油配方(体积分数:复配乳化剂2.43%,蓖麻油1.08%,柴油81.49%,HLB值5.77,葡萄糖水溶液15%和溶液中葡萄糖质量分数16.83%),此时葡萄糖乳化柴油稳定时间为264.2 h,与最优配方参数取整后试验稳定时间误差为4.62%。最后分别用0#柴油、葡萄糖乳化柴油(最优配方)进行稳态试验(European stationary cycle,ESC),试验结果表明,燃用葡萄糖乳化柴油和0#柴油时,发动机油耗量的费用分别为1.786和1.598元/(k W·h)。研究成果可为生物燃料的产业化开发和应用提供参考。     

乳化牛油的工艺研究

研究了不同乳化剂对牛油的乳化效果。根据乳液的稳定性来选择其最佳的亲水亲油平衡值(HLB)为10.53。在最佳HLB值下进行乳化剂的复配。当Tween80和单甘酯以3∶2的比例复配,且复配乳化剂的添加量为0.8%时,乳化牛油的效果最好。增稠剂可增强乳液的稳定效果,通过L9(34)正交试验确定的最佳增稠剂配比为黄原胶0.1%,瓜尔豆胶0.25%和卡拉胶0.1%,由此得到最稳定的乳液,其稳定系数为0.963。     

复配乳化剂乳化柴油的经济性和排放特性

为了研究乳化柴油的经济性和排放特性,该文以亲水亲油平衡值HLB（hydrophilic and lipophilic balance）选择复配乳化剂,通过适当的乳化工艺配制乳化柴油,并在1135柴油机上对乳化柴油和纯柴油的经济性和排放特性进行了对比试验。研究结果表明,在柴油机结构参数和调整参数不作改变的情况下,柴油机燃用乳化柴油的碳烟和NOX排放显著降低且有一定的节油效果;添加了助燃剂二茂铁的乳化柴油在降低碳烟、NOX和HC排放方面优势更加明显;含水率的不同对乳化柴油的燃烧有一定影响,综合考虑节油及排放效果,确定了适用本机的较佳含水率体积百分数为13%。该研究结果对于改善发动机经济性和降低排放具有实际的应用价值。     

气流式锐孔法制作猕猴桃籽油微胶囊的研究

猕猴桃籽油含有60%以上的α-亚麻酸，为了防止α-亚麻酸的氧化，本文对“气流式锐孔法”制作猕猴桃籽油微胶囊的工艺、产品的微观结构以及抗氧化性能进行了研究。结果表明：采用“气流式锐孔”装置进行猕猴桃籽油微胶囊化，壁材海藻酸钠适宜的质量分数为2.5%，壁材海藻酸钠与心材猕猴桃籽油最佳质量比为1∶1，乳化剂最适用量为0.1%单甘酯＋0.2%吐温-80，凝固浴CaCl₂适宜的质量分数为2%；喷雾造粒工艺参数物料流量为20 mL/min，喷雾气体压力为0.05 MPa，喷雾造粒液面距为40 cm。猕猴桃籽油微胶囊产品具有很好的微观结构和抗氧化性能。     

乳化剂及助乳化剂提高生物油/柴油乳化性能

为了研究乳化剂和助乳化剂对生物油/柴油乳化性能的影响,利用非离子复配表面活性剂,宏观上以乳化油的稳定性和吸光度比值K为观测对象,微观上以乳化油滴的平均粒径和粒径分布为观测对象,着重研究了乳化剂种类、亲水亲油平衡值HLB值、乳化剂用量、助乳化剂种类、助乳化剂含量等对生物油/柴油乳化油稳定性的影响。试验结果表明：用失水山梨醇单油酸酯和聚氧乙烯失水山梨醇单油酸酯作为混合乳化剂试验效果最好,乳化油的稳定时间最长,达到17 d,吸光度比值K最小,为1.11,稳定性最好。HLB值的最佳范围为5.0～5.8。乳化油生产中,较合适的乳化剂加入量为5%。使用正辛醇和甲醇做助乳化剂可提高乳化油的稳定性,考虑到助乳化剂成本因素,使用甲醇做助乳化剂更适宜。助乳化剂甲醇含量为20%时乳化油稳定性最佳。随着时间推移,乳化油会经历分层、絮凝、聚结与破乳过程。该文可为生物燃油的产业化开发和应用提供参考。     

生物质热解燃油在柴油机上的应用效果

生物质通过快速热解得到的生物质热解燃油主要成分为含氧有机混合物和水,不宜直接作为燃料使用,但与柴油乳化后可实现其在发动机上的应用。在确定生物质热解燃油/柴油乳化油乳化剂的最佳亲水亲油平衡（HLB）值后,利用超声波乳化装置制备了生物质热解燃油质量分数为10%的乳化油（用BPO10表示）,然后在一台未作改动的直喷式柴油机上对燃用BPO10时的燃烧和排放进行了研究。结果表明,生物质热解燃油/柴油乳化油乳化剂的最佳HLB值约为5.8。与0号柴油相比,发动机燃用BPO10时燃烧始点推迟,预混燃烧放热峰值明显升高,扩散燃烧放热峰值略低,最高燃烧压力较低,燃烧持续期缩短;燃用BPO10时有效燃油消耗率较高,而有效热效率与0号柴油的相当;燃用BPO10时可同时大幅降低NOx和碳烟排放,但HC和CO排放升高。     

胰蛋白酶对壳聚糖的降解研究

用粘度法和吸光度法，研究胰蛋白酶非专一性降解壳聚糖过程中温度、PH值、反应时间、酶浓度、底物浓度。金属离子对胰蛋白酶降解壳聚糖反应的影响，确定了以壳聚糖为底物的胰蛋白酶的一些催化特性：最适温度为30℃，最适PH值为5.0,10-180min内酶反应速度恒定，酶浓度在0.1-0.5g/L的范围内，酶反应速度与酶浓度呈线性关系，米氏常数Km为9.54g/L。     

魔芋生物碱的微胶囊化工艺及生防效果试验

为研究生物碱微胶囊及其生物防治效果，对魔芋生物碱进行提取分离，并以其为芯材，以海藻酸钠和魔芋胶为壁材，用锐孔-凝固法研究魔芋生物碱微胶囊的工艺条件。探讨了壁材组成、氯化钙浓度、固化时间及下滴速度和高度对微胶囊效果的影响。结果表明，飞粉与乙醇配比以1∶3，常温下机械桨叶高速搅拌48 h为佳。干柱层析时以甲醇为展开剂，且展开剂与被展开溶液之间配比以3 mL∶3 mL效果最好。正交试验结果表明，海藻酸钠和魔芋胶的最佳配比为10∶1，氯化钙浓度为0.25 mol/L，固化最佳时间为10 min，下滴速度和高度分别以120～180滴/min和10～15 cm为宜；将所制得的生物碱微胶囊经过虫效的生防试验，探讨其引诱和忌避的效果。     

核桃油微胶囊化工艺的研究

为了防止核桃油的氧化，扩大核桃油的用途，用分子络合、乳化包埋、复凝聚等方法对超临界CO₂流体萃取的核桃油进行了微胶囊化研究，以确定产品的最佳生产工艺条件。试验结果表明：采用喷雾干燥法，以大豆分离蛋白和麦芽糊精、β-环状糊精和阿拉伯胶、明胶和阿拉伯胶为壁材，均可制得高质量高包埋率的核桃油微胶囊产品；喷雾干燥法制备核桃油微胶囊适宜的工艺参数为：进料浓度20%～30%，进料温度50～60℃，进风温度160～180℃，出风温度70～80℃。     

柴油机随车乳化系统的实验研究

提出了柴油机随车乳化系统的概念，设计制造了随车乳化系统的主要元件——CES（浮子室式油水配比器），通过实验验证柴油机的燃油供应系统（高压油路）具有良好的乳化能力。利用柴油机自身乳化能力的随车乳化系统，可以避免使用动力输入，有利于乳化油技术的推广应用。实验证明，随车乳化系统必须使用一定量的乳化剂，乳化剂能够维持油水混合液的动态稳定性。     

适宜物理-酶联合改性提高酸性条件下大豆分离蛋白乳化性

为提高酸性条件下大豆分离蛋白（soy protein isolates,SPI）的乳化性能,该文研究了物理-酶联合改性对SPI（pH值为4）的乳化性能影响,通过对比确定了物理-酶联合改性,即超声波-酶复合改性和挤压膨化-酶复合改性两种改性方法在酸性条件下的乳化性能效果最好;并通过对改性后 SPI（pH 值为4）进行溶解性、游离巯基、二硫键、粒径、扫描电镜（scanning electron microscope,SEM）和激光共焦扫描显微镜（confocal laser scanning microscopy,CLSM）分析,从蛋白结构变化上进一步揭示了乳化性能提高现象的原因。结果表明：超声波联合植酸酶-酸性蛋白酶改性的 SPI （Uphy-aci-SPI）的乳化活性（emulsifying activity index,EAI）为0.53 m2/g,比未改性SPI（0.18 m2/g）显著提高了196%（P<0.05）,乳化稳定性（emulsifying stability index,ESI）为17 min,比未改性SPI（13.5 min）显著提高了25.9%（P<0.05）;挤压膨化联合菠萝蛋白酶改性的SPI（Ebro-SPI）的EAI为0.46 m2/g,比未改性SPI显著增加了155%（P<0.05）,ESI为17 min,比未改性SPI显著增加了25.9%（P<0.05）。在pH值为4的条件下对物理-酶联合改性的SPI的性质分析发现,物理-酶联合改性的SPI与未改性SPI相比,物理-酶联合改性的SPI的溶解性显著增加（P<0.05）;物理-酶联合改性的SPI的乳状液平均粒径减小,CLSM观察乳状液中油与蛋白溶液稳定共融,改善了油滴之间的空间排斥力。物理-酶联合改性的SPI游离巯基的含量显著增加（P<0.05）,二硫键含量显著降低（P<0.05）。SEM观察物理-酶联合改性的SPI为结构松散、破碎均一的微观结构。由此可见,乳化性能的提高是通过深层改变蛋白的结构来实现的。该研究可为探索提高酸性条件下SPI的乳化性能的方法提供理论依据。     

米糠谷蛋白与β-环状糊精热聚集对乳化性质和结构特性的影响

为提高米糠谷蛋白功能性质,本研究对米糠谷蛋白与β-环状糊精进行复合热处理（温度60、70、80、90、99℃,时间40、80、120、160、200 min）,分析复合聚集体的浊度、接枝度、乳化性质及结构特性等,探究米糠谷蛋白与β-环状糊精复合热聚集行为。结果表明,米糠谷蛋白与β-环状糊精在90℃条件下加热复合160 min时,复合聚集体乳化活性指数达到最大,与天然米糠谷蛋白相比提高了2.39倍;在80℃条件下加热复合200 min时,复合聚集体乳化稳定性指数最大,与天然米糠谷蛋白相比提高了2.39倍。复合物在80℃条件下受热后,米糠谷蛋白与β-环状糊精结合生成较大颗粒的聚集体;复合物中米糠谷蛋白肽链结构打开,游离巯基含量增加,二硫键断开,疏水基团暴露,β-折叠向α-螺旋和β-转角转化,以共价键的形式形成分子间氢键,使得复合聚集体分子更好地结合到油水的界面,复合聚集体乳化活性和稳定性显著提高（P<0.05）。本研究结果为后续米糠蛋白质功能性质的改善及米糠蛋白质的深加工提供了理论依据。     

茶多酚对淀粉酯纳米颗粒及其稳定的Pickering乳液性质的影响

为探究茶多酚（Tea Polyphenols, TPs）对辛烯基琥珀酸酐（Octenyl Succinic Anhydride, OSA）酯化淀粉纳米颗粒（Starch Nanoparticles,SNPs）及其稳定的Pickering乳液性质的影响,该研究在制备OSA-SNPs的过程中添加TPs,研究TPs对OSA-SNPs的理化性质和乳化性能的影响。结果发现,添加TPs使OSA-SNPs的平均粒径增加、表面Zeta电位绝对值下降、接触角减小（P<0.05）。通过傅立叶红外光谱扫描发现,TPs与OSA-SNPs之间存在氢键和疏水相互作用。在TP-OSA-SNPs稳定的乳液中,增加TP-OSA-SNPs的质量浓度（从0.5 g/mL至2.0 g/mL）,乳滴平均直径明显减小（P<0.05）;当TP-OSA-SNPs的质量浓度增加至2 g/mL时,乳液形成了油滴紧密堆积的界面结构,能够抑制油滴迁移。通过加速氧化试验发现,与OSA-SNPs相比,TP-OSA-SNPs稳定的乳液中氢过氧化物值（Peroxide Value, POV）相对较低（P<0.05）,说明TP-OSA-SNPs具有延缓乳液中油脂氧化的作用。结果表明,这种新型具有抗氧化功能的食品级颗粒乳化剂,对构筑淀粉基Pickering乳液载体具有潜在价值。     

Effect of ultrasound emulsification on cheese aroma encapsulation by carbohydrates

The encapsulation of liquid cheese aroma (20%) in different carbohydrate matrices by spray-drying was investigated. Carbohydrate stabilized emulsions have been prepared by two emulsifying methods, ultrasonic or Ultra-Turrax treatments, and have been compared in terms of emulsion stability and encapsulation efficiency. The use of ultrasound is particularly effective to obtain a stable emulsion with maltodextrin as support, which is known for poor emulsification properties. In the same way, the spray-dried maltodextrin microcapsules were more effective for retaining cheese aroma when ultrasound (12.7 g/100 g of dry powder) was used for the emulsification step rather than Ultra-Turrax (10.7 g/100 g of dry powder). In terms of encapsulation efficiency, the best system of cheese aroma encapsulation is obtained using ultrasound for the emulsification step and modified starch as support (94.3%). With this support, the positive effect of ultrasound resulted in a lower microcaspsule size and in a higher aroma retention than when Ultra-Turrax was used (83.3%). Studies on the aroma profiles showed changes after encapsulation that depend not only on the nature of the support and the emulsification method but also on the interactions between the aroma compound and the matrix. In terms of flavor quality, the best system of cheese aroma encapsulation is obtained using ultrasound and maltodextrin as support.     

Microstructure of α‐Crystalline Emulsifiers and Their Influence on Air Incorporation in Cake Batter

The microstructure of α‐gel and β‐crystalline emulsifiers and their effects on cake batter foam have been studied with polarized light microscopy, confocal laser scanning microscopy (CLSM) and image analysis, freeze‐etching, and transmission electron microscopy (TEM). The emulsifiers Colco and Aroplus, which are commercial α‐gels, and the monoglyceride Dimodan P in its α‐gel and β‐crystalline forms were added to the batter in concentrations of 0.8, 2.0, 3.1, and 4.2%. Dimodan P α‐gel was also prepared with three NaCl concentrations (0.05, 0.67, and 1.35‰). The distribution of air in the foam was evaluated with density measurements and with image analysis of bubbles in optically sectioned batter. In the cake batter, all the α‐gel emulsifiers decreased the density, thereby increasing the incorporation of air, more than the β‐crystalline emulsifier, which did not have any effect on the density. There were noticeable differences in microstructure between the different α‐crystalline emulsifiers. Large, regular α‐structures seemed to increase the batter volume and interfacial area more than smaller aggregates. Adding salt in the emulsifier gel changed the structure, probably into α‐lamellar liposomes, which impaired the aerating effect at lower concentrations.     

Importance of Protein‐Rich Components in Emulsifying Properties of Corn Fiber Gum

Purified corn fiber gum (CFG‐F) isolated from fine (kernel endosperm‐derived) corn fiber that contained ≈2% residual protein was extracted with 70% aqueous ethanol. The aqueous ethanol extract (AEE), which contained 19.5% of the total CFG, contained a high percentage of the proteinaceous material present in the original gum sample. The AEE gum contained 6.81% protein by weight. The residue (R), which constituted 66% of the total CFG‐F, contained only 0.55% of protein. The emulsifying properties of R and AEE in a model oil‐in‐water emulsification system were studied by measuring turbidity after 1, 2, and 3 weeks, particle size after 4 weeks, and by confocal laser scanning microscopy after three months of storage at room temperature. These gums were compared with the standard well‐known emulsifiers native acacia gum (NAG) and modified acacia gum (MAG). The results indicate that although AEE contains protein‐rich components, it is not as good an emulsifier as the residue which contains only 0.55% of protein. However, emulsions prepared with the whole (unfractionated) CFG‐F under similar conditions were more stable showing higher turbidity and smaller particles size than those prepared with either R or AEE.     

Comparative evaluation of the emulsifying properties of phosphatidylcholine after enzymatic acyl modification

The ability of enzymatically synthesized structured phosphatidylcholine (PC) containing caprylic acid to form and stabilize oil-in-water emulsions prepared with different triglycerides [medium chain triglycerides (MCT), soybean oil, and enzymatically synthesized structured lipids] was examined and compared with natural soybean PC and deoiled lecithin. Emulsions were prepared with varying oil and emulsifier concentrations. The particle size distribution, creaming stability, and viscosity were measured for the evaluation of the emulsifying properties. With an increase in the oil concentration, there was an increase in particle size, viscosity, and creaming layer. With an increase in the phospholipid (PL) concentration, there was usually a decrease in particle size and an increase in viscosity, where the emulsion stability was increased. General emulsions prepared with structured lipids resulted in smaller particle sizes as compared to MCT and soybean oil. Deoiled lecithin was able to increase the viscosity more significantly and give smaller particle sizes as compared to the other emulsifiers, thus producing more stable emulsions. However, in certain cases, structured PC was superior to deoiled lecithin and soybean PC. This observation was made for emulsions prepared with soybean oil or structured lipid at an oil/water ratio of 10:90. At an oil/water ratio of 30:70, the deoiled lecithin performed better as compared to the other PLs with all oil types. However, structured PC produced more stable emulsions as compared to natural soybean PC in MCT and soybean oil.     

Retention of a European pear aroma model mixture using different types of saccharides

Eight types of microcapsules of European pear (La France) aroma model mixture were prepared, and their retained aroma components and sample microstructures (both surface and cross-section) were compared. The La France pear aroma model mixture was prepared by the mixing of hexanal and five kinds of esters. alpha-Cyclodextrin (alpha-CD), gum arabic (GA), soybean soluble polysaccharide (SSPS), and highly branched cyclic dextrin (HBCD) were used as carrier solids, and spray drying and freeze drying comprised the drying methods. The mean particle size of the microcapsules ranged from 8.34 microm for the microcapsules with alpha-CD to 9.67 microm for those with SSPS. The total aroma contents were different depending upon the microencapsulation systems (1.35 g/100 g of microcapsules for the spray-dried microcapsules with HBCD to 14.1 g/100 g of microcapsules for the freeze-dried microcapsules with GA). The microcapsules with alpha-CD and GA were stable against heat treatment (40, 80, or 120 degrees C for 60 min) under nitrogen gas flow.     

Contribution of the interfacial layer to the protection of emulsified lipids against oxidation

The oxidative stability of oil-in-water (O/W) emulsions is highly dependent on the type of emulsifier. The purpose of this work was to investigate the specific role of the adsorbed emulsifiers on lipid oxidation of O/W emulsions. Emulsions of similar droplet size distribution stabilized by minimum amounts of proteins or surfactants were oxidized at 25 °C in the presence of equimolar iron-EDTA complex. The pH and the amount of emulsifier in the aqueous phase were also varied to investigate the role of the droplet charge and the emulsifier in the aqueous phase. Oxygen uptake, conjugated dienes (CD), and volatile compound formation demonstrated that the protein-stabilized interfaces are less efficient at protecting emulsified lipids against oxidation than surfactant-stabilized interfaces. The antioxidant effect of unadsorbed proteins was also confirmed.