改性凹凸棒黏土/羧甲基壳聚糖协同稳定桉叶精油Pickering乳液制备及缓释抑菌性能

以油酸钠表面改性的凹凸棒黏土（modified-attapulgite,M-APT）与羧甲基壳聚糖（carboxy-methyl chitosan,CMCS）协同稳定制备桉叶精油Pickering乳液,通过乳液静置乳析、乳滴显微形貌及流变学性质,考察M-APT、CMCS质量分数及桉叶精油体积分数对乳液稳定性影响。结果表明,油酸钠改性使APT接触角θ从15.2°增大到83.7°,可不可逆吸附于油滴表面,乳滴粒径随M-APT质量分数增大而减小;亲水CMCS链自组装包封表面吸附M-APT粒子的油滴。乳液储存模量（G’）随CMCS质量分数增加明显增大,乳液稳定性增强。琼脂盘打孔法,对比考察纯桉叶精油和乳液对金黄色葡萄球菌和枯草芽孢杆菌的抑菌活性,发现乳液体系抑菌圈直径均略大于纯精油体系,这主要是因为M-APT吸附在油滴表面实现了对精油的包封,降低了其挥发性。菌类生长动力学实验也证实了这一结果,即M-APT/CMCS协同作用可实现对精油的包封稳定,提高其抑菌活性和实现长效缓释抑菌,这对拓展植物精油在生物抑菌剂方面的应用具有重要的参考价值。     

大豆分离蛋白-甜菊糖苷复合稳定剂制备纳米乳液

为适应食品工业对食品配料天然绿色、营养健康的追求,采用大豆分离蛋白（soy protein isolate,SPI）-甜菊糖苷（steviol glycosides,STE）复合体系作为稳定剂制备纳米乳液,研究稳定剂组成、微射流参数、油相质量分数等对纳米乳液形成的影响,并对乳液稳定性及微结构进行表征。结果表明：油相质量分数为10%时,单独SPI（1%）制备的乳液粒度较大（d43为0.548 μm）,稳定性差。添加0.25%～1% STE时,乳液粒度分布更均匀,粒度变小;当STE质量分数为0.5%和1%时,乳液粒度小于200 nm,且具备较好的贮存稳定性（30 d）。添加2% STE会导致乳滴表面蛋白被完全取代,从而弱化乳液的长期稳定性。微射流压力、均质次数及STE质量分数的增加均可降低乳液粒度,但油相质量分数的增加可增加乳液粒度。进一步将纳米乳液进行冷冻干燥处理,可制得结构化良好且高油含量的油粉;相对于单独SPI稳定的结构化乳液,SPI-STE纳米乳液制得的油粉结构更为完整,表面黏性小。     

花生蛋白-果胶复合乳液凝胶的流变学特性和微观结构

研究不同油相及其添加量对转谷氨酰胺酶诱导制备的花生蛋白-果胶复合乳液凝胶质地特性的影响规律,同时通过流变学和微观结构特性研究探索乳液凝胶的形成机理。结果表明：花生蛋白-果胶复合乳液凝胶的凝胶强度显著高于水凝胶。凝胶外观和储能模量（G’）结果表明油滴与蛋白-果胶组成的凝胶基质相互作用,从而影响乳液凝胶的质地和凝胶强度。油相添加量的增加可以使乳液凝胶的力学性能增强,网络结构更稳定。花生蛋白-果胶复合乳液凝胶的G’值和硬度随油相添加量的增加而增大,说明分散的油滴作为活性填料与凝胶基质相互作用。花生蛋白-果胶复合乳液凝胶的微观结构结果表明,油相添加量60%（V/V）时24度棕榈油为油相的乳液凝胶网络结构更致密。研究结果为花生蛋白-果胶复合乳液凝胶在食品领域的开发利用提供思路。     

油相结构化对大豆蛋白藻油纳米乳液氧化稳定性的影响

利用蜂蜡结构化藻油结合大豆分离蛋白-甜菊糖（soy protein isolate-stevioside,SPI-STE）复合体系的乳化特性,制备高稳态的藻油纳米乳液体系。藻油凝胶的微观结构观察、热性质测试以及流变学分析表明,当藻油中蜂蜡添加量达到4%(m/m)时,大量晶体组装成稳固的网络结构,从而构筑出稳定的油凝胶。进一步以SPI-STE为稳定剂制备藻油纳米乳液,研究了藻油结构化对纳米乳液形成及稳定性的影响。结果表明,油相中添加蜂蜡对纳米乳液的形成没有显著影响。随着藻油中蜂蜡质量分数的增大（0%～6%）,乳液的物理稳定性逐渐提高;但在高蜂蜡添加量（8%）下,刚性较强的凝胶网络破坏了油滴界面层,乳液稳定性变差。热促氧化及光促氧化结果显示,蜂蜡油相结构化明显提高了纳米乳液的氧化稳定性,其中油相中含有6%蜂蜡的样品延缓氧化的效果最明显。本研究可为食品工业构建高稳态的藻油纳米乳液载体及产品提供一定技术支持。     

肉桂酸基油凝胶及其乳液的制备及理化性质表征

选择玉米油为溶剂,肉桂酸为凝胶剂制备油凝胶,探究其流变学、质构、持油性、热力学特性及凝胶剂晶体形态;以油凝胶为分散相,制备油凝胶乳液（O/W型）,分析其粒径、流变学、稳定性等物理性质。结果表明：肉桂酸临界成胶质量分数为4%,4?℃条件下存放的油凝胶持油性较常温条件下更好;肉桂酸质量分数越大的油凝胶硬度越大,热稳定性越好;肉桂酸在油凝胶中呈现随机分布的长纤维状聚集体;油相质量分数为10%～20%时,油相含量越低,其乳液粒径越小、黏度越低、物理稳定性越好。油凝胶在常温下稳定性较差,而油凝胶乳液在常温下能保持良好的稳定性,有益于其在食品工业领域的研发与应用。     

缓释型茶树精油-壳聚糖微胶囊的制备、表征及体外释放规律

以三聚磷酸钠（sodium tripolyphosphate,TPP）为交联剂,采用离子凝胶法制备茶树精油-壳聚糖（chitosan,CS）微胶囊,研究茶树精油微胶囊的结构和功能特性,并分析茶树精油微胶囊在不同食品模拟体系中的释放规律。结果表明,茶树精油添加量和CS与TPP质量比对微胶囊粒径和茶树精油包埋率有显著影响,通过优化得到CS与TPP质量比5.3∶1、茶树精油添加量11.30 mg/mL时,茶树精油微胶囊的粒径最小为（0.74±0.03）μm,包埋率最大为（53.15±0.32）%。该条件下微胶囊的粒径范围在0.2～2.3 μm之间,且呈正态分布;并且可以明显提高茶树精油的稳定性,表现为与茶树精油相比,茶树精油微胶囊在0～15 d时,有更稳定的体外杀菌性和抗氧化性。另外,茶树精油微胶囊在不同的食品模拟体系中均能快速释放,并在30 min后逐渐稳定。说明该工艺可以用于对茶树精油的微囊化包埋,从而提高茶树精油的稳定性。     

利用两性小分子甘草酸制备乳液凝胶及其性质分析

液态油脂结构化研究目前是现代食品加工业的热点问题。本文利用三萜化合物甘草酸铵作为天然结构化材料,将液态植物油结构化形成乳液凝胶（Emulsion gel）。该乳液凝胶油含量高,且制备方法简单温和。利用激光共聚焦显微镜和偏光显微镜观察的微观结构显示,在较高的甘草酸铵浓度和油含量下,作为活性填充颗粒的油滴紧密堆积在凝胶网络中,强化了凝胶结构。流变学测试结果也显示,在相同甘草酸铵浓度下,制备的乳液凝胶强度显著高于相应浓度的水凝胶。另外,荷载β-胡萝卜素对凝胶结构性质影响不明显,而且乳液凝胶保持良好的稳定性,表明该乳液凝胶具备作为油溶性生物活性物质输送体系的潜力。研究结果显示,利用两性小分子甘草酸铵作为天然结构化材料制备的乳液凝胶在功能性食品和药品等领域都具有宽阔的应用前景。     

肉桂精油乳液的制备及抑菌性

肉桂精油具有抑菌杀菌、抗氧化等功效,但因其水溶性差、易挥发、稳定性差,限制了应用。将肉桂精油溶解于中链脂肪酸,以司班20与吐温80为乳化剂,制备水包油型乳液。通过改变肉桂精油的质量分数（0%~2.5%）,可得粒径分布在50~280 nm乳液。离心实验发现,该乳液稳定性好,且适宜于在温度低于40 ℃条件下使用。在25 ℃下储藏10 d,乳液的粒径和分散系数几乎不变。此外,利用比浊法测定不同粒径的乳液抑菌效果发现,粒径为150 nm的肉桂精油乳液对大肠杆菌和金黄色葡萄球菌的抑制效果最好。     

天然油脂乙氧基化物稳定高内相乳液影响因素的研究

以棕榈仁油乙氧基化物(SOE-N-60)为表面活性剂稳定高内相乳液(HIPEs)。通过对乳液外观、微观结构、粒径分布、黏度和流变学测试，研究了油相体积分数、SOE-N-60添加量对HIPEs性能的影响，同时对其稳定性进行考察。结果表明：SOE-N-60添加量为0.6%~1.5%（油相体积分数为83%）、油相体积分数为74%~86%（SOE-N-60添加量为1.0%）时可形成稳定的HIPEs，此时乳液液滴内部形成紧密堆积的网络结构，乳液粒径变小，具有弹性凝胶性质，并展现出很好的黏弹性和触变性，且随着油相体积分数和SOE-N-60添加量的增大，乳液黏弹性逐渐增强，同时HIPEs在(-5±1) ℃、(25±1) ℃、(40±1) ℃下贮存24 h时均具有良好的稳定性。     

球磨-酯化复合改性槟榔芋淀粉对Pickering乳液形成的影响

为了提高淀粉颗粒的乳化能力,以球磨-酯化复合改性槟榔芋淀粉为颗粒乳化剂,大豆油为油相,制备水包油型Pickering乳液.采用激光粒度仪、研究级正置显微镜、流变仪等对Pickering乳液外观、液滴粒径、显微形态及动态流变特性进行表征,考察淀粉颗粒质量浓度(1、5、10、20、30 mg/mL)和油相体积分数(10％、20％、30％、40％、50％)对乳液稳定性和流变特性的影响.研究发现:增加颗粒质量浓度导致乳化相体积增加,液滴粒径减小;随着油相体积分数的增加,乳化相体积增加,液滴粒径增大.当颗粒质量浓度为20 mg/mL,油相体积分数为40％时,乳液的乳析现象明显改善.球磨-酯化复合改性槟榔芋淀粉颗粒吸附在油/水界面,有效抵抗了液滴聚结,使乳液在储存30 d后仍表现出良好的稳定性.流变特性表明:乳液内部存在弹性凝胶网络结构,随着颗粒质量浓度和油相体积分数的增加,液滴间堆积变得更紧密,从而增加了乳液黏度和凝胶强度,使其抵抗形变能力增强.球磨-酯化复合改性槟榔芋淀粉颗粒具有良好的作为Pickering乳液稳定剂的潜力.     

Combined microscopic and dynamic rheological methods for studying the structural breakdown properties of whey protein gels and emulsion filled gels

The microstructural and large deformation rheological properties of model food gels were studied by performing notch propagation tensile testing on the gels using a tensile stage and observing changes in the microstructure of the gels during tensile testing using confocal laser scanning microscopy (CLSM). Heat-set whey protein (WP) gels containing either added sodium caseinate (NaCN) or sunflower oil droplets emulsified with WP or NaCN as the emulsifier protein were prepared in 0 or 50 mM NaCl. The WP gel structure strengthened in the presence of added NaCl and NaCN. The rheological properties of WP gels containing sunflower oil droplets emulsified with WP or NaCN were influenced by the NaCl concentration, oil concentration and extent of oil droplet aggregation in the gel or by the type of emulsifier protein used. During tensile testing, the notch length in all gels increased above a certain critical stress, leading to fracture of the gels through the notch. Also, the microstructural changes in the oil phase of emulsion filled gels subjected to tensile testing were influenced by the structural properties of the WP gel matrix and the proximity of the oil droplet to the fracture path.     

Physical and antimicrobial properties of chitosan–tea tree essential oil composite films

Antimicrobial films were prepared by incorporating different concentrations of tea tree essential oil (TTO) into chitosan (CH) films. Film-forming dispersions (FFD) were characterized in terms of rheological properties, particle size distribution and ζ-potential. In order to study the impact of the incorporation of TTO into the CH matrix, the water vapour permeability (WVP), mechanical and optical properties of the dry films were evaluated. The properties of the films were related with their microstructure, which was observed by SEM. Furthermore, the antimicrobial effectiveness of CH–TTO composite films against Listeria monocytogenes and Penicillium italicum was studied.     

Application of whey protein emulsion gel microparticles as fat replacers in low-fat yogurt: Applicability of vegetable oil as the oil phase

Low-fat, healthy yogurt is becoming increasingly favored by consumers. In the present study, whey protein emulsion gel microparticles were used to improve the quality of low-fat yogurt, and the effects of vegetable oil emulsion gel as a fat substitute on the qualities of low-fat yogurt were investigated, expecting to obtain healthier and even more excellent quality low-fat yogurt by applying a new method. First, emulsion gel microparticles were prepared, and then particle size distribution of emulsion gel and water holding capacity (WHC), textural properties, rheological properties, microstructure, storage stability, and sensory evaluation of yogurt were carried out. The results showed that yogurt with emulsion gel had significantly superior qualities than yogurt made with skim milk powder, with better WHC, textural properties, rheological properties, and storage stability. The average particle size of whey protein-vegetable oil emulsion gel microparticles was significantly larger than that of whey protein-milk fat emulsion gel microparticles, and the larger particle size affected the structural stability of yogurt. The WHC of yogurt made with whey protein-vegetable oil emulsion gel microparticles (V-EY) was lower (40.41%) than that of yogurt made with whey protein-milk fat emulsion gel microparticles (M-EY; 42.81%), and the texture results also showed that the hardness, consistency, and viscosity index of V-EY were inferior to these of M-EY, whereas no significant differences were found in the cohesiveness. Interestingly, the microstructure of V-EY was relatively flatter, with more and finer network branching. The whey separation between V-EY and M-EY also did not show significant differences during the 14 d of storage. Compared with yogurt made with whey protein, vegetable oil, and skim milk powder, the structure of V-EY remained relatively stable and had no cracks after 14 d of storage. The sensory evaluation results found that the total score of V-EY (62) was only lower than M-EY (65) and significantly higher than that of yogurt made with skim milk powder. The emulsion gel addition improved the sensory qualities of yogurt. Whey protein emulsion gel microparticles prepared from vegetable oil can be applied to low-fat yogurt to replace fat and improve texture and sensory defects associated with fat reduction.     

Characterization of edible films based on hydroxypropylmethylcellulose and tea tree essential oil

Edible films based on hydroxypropylmethylcellulose (HPMC) and different concentrations of tea tree essential oil (TTO) were prepared. Film-forming dispersions (FFD) were characterized in terms of rheological properties, particle size distribution and ζ-potential. In order to study the impact of the incorporation of TTO into the HPMC matrix, the water sorption isotherms, water vapour permeability (WVP), mechanical and optical properties of the dry films were evaluated. Results showed that the increase in TTO content promoted significant changes in the size and surface charge of the FFD particles. With regards to the film properties, the higher the TTO content, the lower the WVP and the moisture sorption capacity. In general, the addition of TTO into the HPMC matrix leads to a significant decrease in gloss and transparency and a decrease in the tensile strength and elastic modulus of the composite films. The properties of the films were related with their microstructure, which was observed by SEM.     

纳米SiO2改性4 种大分子材料的乳液制备及性质

为提高乳液稳定性,采用纳米SiO2改性明胶（gelatin,GE）、大豆分离蛋白、壳聚糖和阿拉伯胶（gum arabic,GA）制备茶油乳液。以乳化活性、乳化稳定性、离心稳定性、平均粒径、流变特性为考察指标,探究质量分数3.000%的纳米SiO2对4 种大分子材料复合乳液性质的影响,并对乳液的微观结构及油滴分布进行观察。结果表明,纳米SiO2能增强乳液稳定性,其中GE-纳米SiO2复合乳液综合性质最佳。添加纳米SiO2后乳化活性和乳化稳定性显著增加（P＜0.05）,离心稳定性降低68.444%。平均粒径为8.472 μm,乳液粒径最小且分布均匀,表面光滑呈球状。流变表现为典型的弱凝胶特性,稳定性良好。研究结果可为天然高分子和纳米SiO2乳液的制备和应用提供实践基础。     

肉桂油对蛋清蛋白/可得然胶凝胶理化特性及释放肉桂醛性能的影响

卤制工艺中风味组分的控制释放有望对卤制品品质的工业标准化程度进行调控。以蛋清蛋白和可得然胶为基质材料,以肉桂油为风味组分代表,水油两相均质后通过热诱导法制备乳液凝胶,探究肉桂油添加对乳液凝胶特性及释放肉桂醛性能的影响。结果表明,与大豆油乳液凝胶相比,肉桂油乳液凝胶颜色偏黄,微观结构更加致密,持水率、硬度、储能模量和损耗模量等参数显著增加,且当肉桂油质量分数为5%时凝胶性能最强。随着肉桂油添加量的增加,凝胶转变时间缩短,同时乳液凝胶的黏弹性减弱,亮度增加、黄度降低。红外光谱证实了肉桂油中的肉桂醛与蛋清蛋白发生了席夫碱反应,从而促进乳液凝胶的形成及凝胶性能的提升。在模拟卤制品加工环境下,肉桂油乳液凝胶对所含肉桂醛具有良好的控释效果:水相中肉桂醛的释放率随肉桂油添加量的增加而减小,当肉桂油质量分数从5%增加至11%时,乳液凝胶在水中煮制1h后,肉桂醛的累积释放率降低35.44%;与在水中煮制相比,调味料氯化钠、醋酸与乙醇可促进水相中肉桂醛的释放,且在醋酸中的累积释放率增幅最大(15.95%);但模拟卤制基质中的蛋白质和多糖会抑制肉桂醛的释放,累积释放率降低9.58%以上。乳液凝胶在模拟食品加工过程中能维持原有块状形貌,但在酸性条件下质地变硬、体积缩小、损失率最大,且凝胶结构破坏程度最严重,促进了肉桂醛的释放。因此,蛋清蛋白/可得然胶乳液凝胶的质地与释放性能可通过肉桂油的活性填充进行调控。研究结果旨在为食品工业中风味控释技术的开发提供理论参考。     

羟丙基甲基纤维素和黄原胶浓度对初榨椰子油乳液及其模板油凝胶构建的影响

本实验采用乳液模板法制备了不同羟丙基甲基纤维素（HPMC）和黄原胶（XG）浓度的初榨椰子油凝胶，对所得乳状液和油凝胶进行了粒径分析、微观结构观察、流变测定、油损失和X-射线衍射（XRD）分析，探讨HPMC和XG浓度对初榨椰子油凝胶形成和物理性能的影响。微观结构和粒径分析结果表明:高浓度HPMC具有较好的乳化性能，获得油滴粒径较小的稳定乳液；XG浓度变化对油滴粒径的影响不显著。流变学结果表明:随着HPMC或XG浓度的增加，乳状液和油凝胶的机械强度也得到提高，所有油凝胶都表现出对时间的依赖性和结构的回复性。油损失结果表明:HPMC浓度的增加对油凝胶损失的影响尤为明显，变化幅度从19.6%降低为3.6%；XG浓度的增加也使油损失从9.62%降低为4.4%。但HPMC和XG浓度的变化对油凝胶的XRD图谱影响不明显。本实验为初榨椰子油凝胶的构建提供了理论基础，也为其实际应用提供了参考。     

Emulsion gels: The structuring of soft solids with protein-stabilized oil droplets

Many food products can be categorized as emulsion gels. This is especially the case for protein-based oil-in-water emulsions which can be converted into soft-solid-like materials by common food processing operations such as heating, acidification, and enzyme action. This review article outlines how the rheological and structural properties of protein-stabilized emulsion gels are influenced by the dispersed oil volume fraction, the oil–water interfacial composition, and the colloidal interactions of the constituent emulsion droplets. For model systems of variable oil content and containing different food proteins, some general trends of rheological behaviour at small and large deformations are identified. Experimental rigidity data are considered in relation to: (i) material science theories of the reinforcement of solid materials by active and inactive filler particles, and (ii) Brownian dynamics simulations of aggregated particle networks containing bonded and non-bonded particles. Influences of interfacial composition and particle–matrix interactions on microstructure and rheology are explained with particular reference to the role of small-molecule surfactants. Compositional and structural factors affecting the large-deformation rheology and fracture properties are described. Finally, the practical relevance of the model system studies to the behaviour of real food products is critically assessed.