阿拉伯胶/壳聚糖复凝聚相的制备及表征

以阿拉伯胶和壳聚糖分别为聚阴离子和聚阳离子,构成复凝聚体系,研究pH、温度、时间、离子强度和总固形物浓度及配比等因素对阿拉伯胶/壳聚糖复凝聚反应的影响。采用傅里叶变换红外光谱和扫描电子显微镜对复凝聚相进行表征。研究结果表明,在未添加NaCl,采用去离子水处理条件下,将1%壳聚糖和6%阿拉伯胶等体积混合,调节pH4.5,于45℃条件下保温10min,此时得到的复凝聚相的浊度为0.929,最大凝聚相产率达86.52%。红外光谱分析表明:复凝聚相是阿拉伯胶和壳聚糖通过静电相互吸引结合而成。扫描电子显微镜图片显示复凝聚相含有大小不一液泡的微观网状结构。     

米谷蛋白-小麦阿拉伯木聚糖复合水凝胶性能研究

目的 研究不同米谷蛋白与阿拉伯木聚糖浓度对复合凝胶性质的影响。方法 本研究采用米谷蛋白与小麦阿拉伯木聚糖作为主材料,通过热处理与漆酶诱导复合处理使得米谷蛋白中的酪氨酸与小麦阿拉伯木聚糖链上的阿魏酸共价交联形成复合水凝胶。比较不同浓度米谷蛋白及阿拉伯木聚糖对复合水凝胶的硬度、流变、持水性及溶胀特性的影响。结果 随米谷蛋白及阿拉伯木聚糖浓度分别升高,其复合水凝胶的凝胶硬度、流变特性、持水能力及溶胀特性均显著提高。但可能因凝胶网络结构及作用力等原因,二者浓度达到一定限度(160 mg/ml、25 mg/ml)后,其持水与溶胀特性略有降低。结论 高浓度材料制备所得米谷蛋白/阿拉伯木聚糖复合水凝胶具有较高的力学性能与保水性能,这也为该水凝胶在食品领域进一步研究提供了一定的理论基础。     

提取条件对粗提取阿拉伯木聚糖中蛋白质残余量影响规律研究

阿拉伯木聚糖粗提物均会残余一定量的蛋白质,这些交联或游离的蛋白质会影响阿拉伯木聚糖的乳化性、溶解性、凝胶特性、成膜性等诸多特性。文章以粗提取阿拉伯木聚糖的蛋白质含量为考察指标,研究了温度、时间、NaOH浓度和pH值对碱提麦麸阿拉伯木聚糖中蛋白含量的影响,并采用正交试验方法对碱提工艺条件进行优化。结果表明,在反应时间120 min、反应温度90℃、NaOH浓度0.25 mol/L、pH值3.8条件下,阿拉伯木聚糖具有最小的蛋白含量(6.339±0.31)%。     

提取条件对小麦麸皮阿拉伯木聚糖相对分子质量分布的影响

以小麦麸皮为原料,通过化学分析法和高效凝胶渗透色谱法,探讨提取时间、pH值和温度对阿拉伯木聚糖提取得率及其产品相对分子质量分布的影响。结果表明,随着提取时间的延长、pH值和温度的升高,阿拉伯木聚糖的得率显著提高。延长提取时间（5 h）,可以提高产品中低相对分子质量阿拉伯木聚糖的含量;提高反应的pH值（13.0）和温度（90 ℃）则可以获得富含多种高相对分子质量阿拉伯木聚糖的产品。     

一步法制备大豆不溶性肽-壳聚糖复合颗粒稳定的Pickering双重乳液及其表征

该研究探讨了大豆分离蛋白（SPI）酶解产生的水不溶性肽聚集体（SWIP）经过超声处理后与壳聚糖（CS）进行复合,所制备的复合胶体颗粒（SWIP-CS）作为乳化剂通过简单的一步均质法制备得到W/O/W型Pickering双重乳液,进一步研究了不同壳聚糖浓度与pH值对乳液外观、粒径、微观结构及流变特性的影响。结果表明,大豆水不溶性肽聚集体与壳聚糖之间通过氢键相互作用。在pH为3.0、3.8、4.0和5.0时,壳聚糖浓度为0.125%、0.25%和0.5%及油相分数50%时均能够制备稳定的Pickering双重乳液。壳聚糖浓度的增加使得乳液的粒径有着显著性的降低（30.6~23.9 μm）,且较高浓度（0.5%）时能够改善双重乳液的稳定性与凝胶特性。而随着pH从3.0增加到5.0,双重乳液液滴内部的小液滴数量逐渐减少,其稳定性与凝胶特性也在相应的降低。本研究为制备双重乳液提供了一种简便有效的策略,对于食品工业、化妆品与医药领域上的应用具有重要意义。     

小麦阿拉伯木聚糖分子特性及单糖组成研究

试验研究并讨论了3种小麦阿拉伯木聚糖(W9023,W58和W27)分子量及单糖组分的差异。通过高效体积排阻色谱及反向高相液相色谱分别对小麦阿拉伯木聚糖的分子量及单糖组分进行分析。碱提小麦阿拉伯木聚糖重均相对分子量可分为高分子量和低分子量2部分,且分子量大小分别为1.25×10~6~1.49×10~6 g/mol和3.6×10~3~3.8×10~3g/mol。单糖组分分析表明,小麦阿拉伯木聚糖主要有Ara,Xyl,Glu和Gal组成,即表现出典型的AX结构。W9023及W27的Ara/Xyl比值相对较高,分别为0.54和0.51。结果表明:不同来源的小麦阿拉伯木聚糖分子特性有差异。W9023及W27具有相对较高的取代度,更利于后续对阿拉伯木聚糖的研究。     

优良乳化特性麦麸阿拉伯木聚糖制备工艺优化

乳状液粒径大小和分布与乳状液乳化特性有着密切的关系,为得到优良乳化特性麦麸阿拉伯木聚糖,以乳液平均粒径及分布为考察指标,研究了碱提温度、碱提时间、NaOH浓度和pH单因素对麦麸阿拉伯木聚糖乳状液粒径的影响,并采用正交实验方法对麦麸阿拉伯木聚糖的碱提工艺条件进行优化。结果表明,在碱提温度85 ℃、碱提时间180 min、NaOH浓度0.15 mol/L、pH4.3条件下,所提取麦麸阿拉伯木聚糖平均粒径为(0.4859±0.009) μm低于阿拉伯胶的(0.5494±0.013) μm,并具有相近的分布指数(0.147±0.015,0.113±0.016,p>0.05)。因此,通过优化提取条件,制备具有优于或接近阿拉伯胶的乳化性质的麦麸阿拉伯木聚糖是可行的,为阿拉伯木聚糖的工业生产提供理论参考。     

阿拉伯木聚糖强化对面团特性和面包烘焙品质的影响

研究阿拉伯木聚糖的添加量对复合面包粉（小麦淀粉-谷朊粉）的加工特性和面包烘焙特性的影响。结果表明：添加阿拉伯木聚糖后,面团体系黏弹性增加,蠕变-恢复性能增加,当阿拉伯木聚糖添加量大于10%时,面团流变性能变差;扫描电子显微镜显示,阿拉伯木聚糖添加量小于15%时,可以促使面团体系内淀粉颗粒聚集,当阿拉伯木聚糖大于15%时,淀粉聚集状态更加紧密,面筋的连续性遭到破坏;质构结果表明：随着阿拉伯木聚糖添加量的增加,面团黏性显著增加（p<0.05）,但当阿拉伯木聚糖添加量大于10%时,面团硬度、咀嚼性和弹性降低;此外,当阿拉伯木聚糖添加量为10%时,面包整体可接受度显著提高（p<0.05）。综上,在复合面包粉中添加10%的阿拉伯木聚糖,可以最大限度地增加面包中阿拉伯木聚糖的含量,同时又可以制得品质良好的面包。     

麦麸阿拉伯木聚糖-牛血清蛋白质酶促共聚物制备及表征

研究麦麸阿拉伯木聚糖与牛血清白蛋白在漆酶的催化下形成酶促共聚物。通过用紫外分光光度法(UVvis)、十二烷基硫酸钠聚丙烯胺凝胶电泳法(SDS-PAGE)及红外光谱法(FT-IR)对酶促共聚物进行定性表征,并测定酶促共聚物与麦麸阿拉伯木聚糖及牛血清白蛋白乳化特性。结果表明,麦麸阿拉伯木聚糖在漆酶的作用下与牛血清白蛋白发生接枝反应,制得的麦麸阿拉伯木聚糖-牛血清白蛋白酶促共聚物(155.8 m~2/g, 23.7 min)运用在乳状液体系中时,乳化活性及乳化稳定性优于麦麸阿拉伯木聚糖/牛血清白蛋白混合物(144.8 m~2/g, 18.5 min)及麦麸阿拉伯木聚糖(75.3 m~2/g, 17.5 min)及牛血清白蛋白单体(128.0 m~2/g, 15.7 min)。     

β聚苹果酸/壳聚糖硝苯地平微胶囊的制备研究

目的:将聚苹果酸(poly malic acid,PMLA)与壳聚糖(CS)发生复凝聚形成微胶囊并对药物硝苯地平进行包埋,制得粒度均一的微胶囊颗粒。方法:根据预实验确定添加顺序和范围,进行Plackette-Burman实验选择影响较强的几个因素,根据(Box-Behnken设计)正交设计得到最优的制备条件。结果:根据实验得出,当条件为β-聚苹果酸浓度1.0g/L、壳聚糖浓度0.5g/L、β-聚苹果酸与壳聚糖溶液体积比2∶1、壳聚糖pH4.0、硝苯地平溶液浓度1.0g/L、硝苯地平添加量3.0mL、β-聚苹果酸溶液滴加速度10.0mL/h、搅拌速度600r/min、体系反应时间45min,所得微胶囊平均粒径525.6nm,平均分散系数0.186.     

Complex coacervation of soybean protein isolate and chitosan

The formation of coacervates between soybean protein isolate (SPI) and chitosan was investigated by turbidimetric analysis and coacervate yield determination as a function of pH, temperature, time, ionic strength, total biopolymer concentration (TB(conc)) and protein to polysaccharide ratio (R(SPI/Chitosan)). The interaction between SPI and chitosan yielded a sponge-like coacervate phase and the optimum conditions for their coacervation were pH 6.0-6.5, a temperature of 25 °C, and a R(SPI/Chitosan) ratio of four independently of TB(conc). NaCl inhibited the complexation between the two biopolymers. Fourier transform infrared spectroscopy (FTIR) revealed that the coacervates were formed through the electrostatic interaction between the carboxyl groups of SPI (-COO(-)) and the amine groups of chitosan (-NH(3)(+)), however hydrogen bonding was also involved in the coacervation. Differential scanning calorimetry (DSC) thermograms indicated raised denaturation temperature and network thermal stability of SPI in the coacervates due to SPI-chitosan interactions. Scanning electron microscopy (SEM) micrographs revealed that the coacervates had a porous network structure interspaced by heterogeneously sized vacuoles.     

Rheological and Microstructural Characteristics of Canola Protein Isolate−Chitosan Complex Coacervates

Wastage of byproducts such as canola meal is a pressing environmental concern, and canola protein isolate (CPI)?chitosan (Ch) coacervates have a good potential to utilize and convert the wastes into a high value added product. Yet so far, there is very limited rheological and microstructural information to assist in proper utilization of CPI ‐Ch complex coacervates. The rheological and microstructural properties of the complex coacervates formed from CPI and chitosan Ch at various CPI‐to‐Ch mixing ratios (1:1, 16:1, 20:1, and 30:1) and pH values (5.0, 6.0, and 7.0) were therefore investigated. These CPI?Ch complex coacervate phases were found to exhibit elastic behavior as evidenced by significantly higher elastic modulus (G?) compared to viscous modulus (G″) in all the tested ratios and pH ranges. They also exhibited shear‐thinning behavior during viscous flow. The complex coacervates formed at the optimum CPI‐to‐Ch ratio of 16:1 and pH of 6.0 demonstrated the highest G?, G″, and shear viscosity, which correlated well with the high strength of electrostatic interaction and thick‐walled, sponge‐like, less‐porous microstructure at this condition. The higher shear viscosity of the coacervate at pH 6.0 was most likely induced by stronger attractive electrostatic interactions between CPI and Ch molecules, due to the formation of a rather densely packed complex coacervate structure. Hence, it can be concluded that the microstructural observations of denser structure correlated well with the rheological findings of stronger intermolecular bonds at the optimum CPI‐to‐Ch ratio of 16:1 and pH of 6.0. The complex coacervate phase formed at a CPI‐to‐Ch ratio of 16:1 and pH of 6.0 also showed glassy consistency at low temperatures and rubbery consistency above its glass‐transition temperature. This study identified the potential for the newly developed CPI–Ch complex coacervate to be used as an encapsulating material due to its favorable strength. This would drastically reduce the wastage of byproducts, provide a solution to tackle the pressing global issue of wastage of byproducts, and bring about a more environmentally friendly paradigm.     

Complex coacervation of pea protein isolate and tragacanth gum: Comparative study with commercial polysaccharides

The ability of pea protein isolates (PPI) to form complex coacervates with tragacanth gum was investigated. The coacervate formation was structurally compared to three other PPI-polysaccharide interaction models: arabic gum and sodium alginate (known to form coacervates with PPI) and tara gum, a galactomannan. The effects of the pH and protein/polysaccharide ratio were mainly investigated using turbidity and zeta potential measurements. Regarding the pH of soluble complex formation, the pH of complex coacervates increased with the increase in protein-anionic polysaccharide mixture ratio. SEM images revealed the ability of the spray-drying process to form spherical particles of pea protein-polysaccharide complexes. The specificity of the microparticle surface was protein-dependent. FTIR analyses of coacervates showed the electrostatic interaction between the PPI and the polysaccharides. The results showed that tragacanth gum could be used as an alternative to gum arabic to form complex coacervates with PPI based on zeta potential measurements and coacervation yield studies.     

Associative interactions between chitosan and soy protein fractions: Effects of pH,mixing ratio,heat treatment and ionic strength

The objective of this paper is to explore the complexation between the soy protein fractions (glycinin and β-conglycinin) and chitosan (CS) and to investigate the influence of pH, mixing ratio, heat treatment and ionic strength. Phase behavior and microstructure showed that soluble complex and coacervate were obtained in glycinin/CS and β-conglycinin/CS mixtures at specific pHs, following a nucleation and growth mechanism. Moreover, the coacervates showed higher thermal stability than protein alone. Specially, the glycinin/CS mixture displayed a gel-like network structure at pH 5.5 and 6.0, and this structure kept the mixture soluble at a long pH region. The turbidity versus ζ-potential pattern showed that, independent of protein, the self aggregation of soy protein fractions and the coacervation of glycinin/CS and β-conglycinin/CS mixtures were all obtained at charge neutralization pH, indicating that the ζ-potential is the most critical parameter to understand the stability of soy protein/chitosan mixture. This predictive parameter was less affected by mixing ratio and heating but was significantly affected by ionic strength because mixing ratio and heating only changed the equilibrium between repulsive and attractive forces in colloid system while sodium chloride destroyed the predictability of colloidal stability via shielding charged reactive sites on both biopolymers to disrupt electrostatic interactions.     

Coacervate formation of α-lactalbumin–chitosan and β-lactoglobulin–chitosan complexes

α-Lactalbumin (α-La) and β-lactoglobulin (β-Lg) are important whey proteins with isoelectric points of pH 4.80 and 5.34, respectively, and evidence negative charge over a range of pHs. Chitosan exhibits a cationic property under pH 6.5. In an effort to determine the physicochemical properties of mixtures of 0.5% α-La and 0.1% chitosan, and 0.5% β-Lg and 0.1% chitosan, optical structure, turbidity, electrophoresis, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were assessed in a pH range of 2.0–8.0. The results demonstrated that α-La, β-Lg, and chitosan precipitated at pH values of approximately 5.0, 5.0, and 7.0, respectively. The mixtures of α-La and chitosan as well as β-Lg and chitosan coacervated at a pH range of 6.0–6.5. The turbidity of α-La and α-La–chitosan achieved a maximum at pH 5.0, whereas those of β-Lg and β-Lg–chitosan achieved maximum values at a pH of 6.5. The electrophoregram showed a large band with high molecular weight in increasing pH values from 5.0 to 6.0, which suggested that α-La and β-Lg form polymers with chitosan. The denaturation temperature and enthalpy of α-La were shown to increase, whereas those of β-Lg were reduced. The SEM images demonstrated that the α-La was characterized by uneven and associated cluster morphology, whereas that of β-Lg was even, globular, and harbored dense particles, whereas the chitosan evidenced a flat morphology. Our assessment of the complex demonstrated that α-La and β-Lg attached to the surface of the chitosan. The α-La–chitosan and β-Lg–chitosan complexes evidenced opposite charges at a pH range of 5.0–6.0, and formed coacervates. It appears, therefore, that the α-La–chitosan and β-Lg–chitosan coacervates might be applied as a delivery system for foods, nutraceuticals, cosmetics, and drugs.     

Soy protein-polysaccharide complex coacervate under physical treatment: Effects of pH,ionic strength and polysaccharide type

The objective of this paper is to explore the effects of pH, ionic strength and polysaccharide type on the aqueous phase behaviors and rheological properties of soy protein isolate-chitosan (SPI-CS) and soy protein isolate-carboxymethyl cellulose (SPI-CMC) coacervates treated by vortex fluidic device (VFD) and shear homogenization. Characterization in terms of phase behavior and microstructures depicted that the VFD and shear homogenization treatments affected only the SPI-CS complex. According to the ζ-potential values at tested pHs (3.0–8.0), both physical processing had insignificant effect on charge stabilization of protein-polysaccharide complex. Both the SPI-CS coacervates (at pH 7.0) and SPI-CMC coacervates (at pH 3.0) showed gel-type rheological behaviors (G′ > 1000 Pa), suggesting that the SPI and polysaccharides did not form complex coacervate (liquid in nature) but interpolymeric complex (solid in nature). In the absence of salt ions, independent on the type of coacervate, VFD slightly decreased the modulus (G′ < 1000 Pa) while homogenization significantly decreased the modulus (G′ < 20 Pa). Alternatively, the addition of salt ions produced an electrostatic shielding and weakened the protein-polysaccharide electrostatic interaction, resulting in a decrease of coacervate modulus. Interestingly, under certain condition, VFD treatment probably promoted the interaction between protein molecules in protein-polysaccharide coacervate, resulting in another increase in the elastic modulus of the complex coacervate.     

α-生育酚壳聚糖纳米粒的制备、表征及体外缓释抗氧化性能

α-生育酚作为天然抗氧化剂和营养强化剂被广泛应用于食品领域,但由于其对氧气、光照、金属离子等环境敏感,易快速失活,且不溶于水,极大地限制了其应用范围。本研究采用乳化-离子凝胶两步法制备α-生育酚壳聚糖纳米粒,将α-生育酚进行包埋。以颗粒平均粒径、多分散系数、表面电位为参考指标,通过单因素及正交试验考察壳聚糖(chitosan,CS)质量浓度、α-生育酚质量浓度、CS与三聚磷酸钠(sodium tripolyphosphate,TPP)质量比、p H值、搅拌速率等因素对纳米颗粒平均粒径和包封率的影响,确定最优制备工艺。采用动态光散射仪、扫描电镜、傅里叶红外光谱对纳米颗粒进一步表征,并考察其体外释放性能和抗氧化效果,以期为α-生育酚在腌腊肉制品后期贮藏过中的脂质抗氧化应用提供理论基础。结果表明,α-生育酚壳聚糖纳米粒最优制备工艺条件为CS质量浓度1 mg/mL、α-生育酚质量浓度1 mg/mL、CS与TPP质量比7∶1、CS初始p H值为4.5、搅拌速率900 r/min。所得纳米颗粒平均粒径214 nm,包封率51.65%。红外光谱表明CS与三聚磷酸钠静电吸附,生育酚被包封。扫描电镜下形态学结构大小均匀,呈规则球形。体外释放实验和抗氧化实验表明α-生育酚壳聚糖纳米粒具有缓释抗氧化作用。     

Complex coacervates obtained from interaction egg yolk lipoprotein and polysaccharides

Protein–polysaccharide coacervates formation was evaluated under influence of pH (3.0, 4.0, 6.5, 8.5 and 10.0), temperature (10, 20, 30, 40 and 50 °C) and polysaccharide mass (0.025, 0.033 and 0.050 g). It was possible to observe that solutions with lower turbidity values were found in pH band 3.0 to 4.0. Statistical analysis of turbidity data have shown that for all polymers pH was meaningful in coacervate formation, although for some, besides pH, temperature and polymer concentration could also influence significantly (p < 0,05) in coacervate formation. Encapsulates morphology made by coacervation was directly linked to the kind of polymer used and its interactional degree. Dehydrated coacervates have presented heterogeneous morphology, different from their original structures.     

壳聚糖/香兰素/聚乙烯醇共纺纳米纤维膜的性质及其在大菱鲆保鲜中的应用

本研究以壳聚糖（chitosan,CS）、香兰素（vanillin,V）和聚乙烯醇（polyethylene alcohol,PVA）为原料,采用单轴静电纺丝工艺制备CS/V/PVA共纺纳米纤维膜,通过场发射扫描电子显微镜、傅里叶变换红外光谱、X射线衍射、差示扫描量热分析和热重分析对CS/V/PVA共纺纳米纤维膜的形貌和结构进行表征,并以大菱鲆优势腐败菌——腐败希瓦氏菌（Shewanella putrefaciens）为靶标菌,对其抑菌活性进行测定,并考察CS/V/PVA共纺纳米纤维膜应用于大菱鲆的保鲜效果。结果表明：CS/V/PVA共纺纳米纤维膜的微观结构良好,纤维直径均匀分布在200～350 nm之间;纤维膜各组分之间存在相互作用,香兰素分子中的醛基能与CS分子中的氨基反应形成席夫碱键,且CS、香兰素、PVA分子间有氢键形成,降低了膜的初始熔融温度。此外,CS/V/PVA共纺纳米纤维膜对腐败希瓦氏菌具有较强的抑制作用,4 ℃大菱鲆保鲜实验结果表明CS/V/PVA共纺纳米纤维膜能有效延长大菱鲆鱼片的货架期。     

Formation of biopolymer-coated liposomes by electrostatic deposition of chitosan

ABSTRACT:  The purpose of this study was to prepare stable biopolymer-coated liposome suspensions using an electrostatic deposition method. Liposome suspensions were produced by homogenizing 1% soy lecithin in acetate buffer (0.1 M, pH 3). Cationic chitosan (Mw approximately 200 kDa) solutions were mixed with anionic liposome suspensions ( d approximately 100 and 200 nm), and the effect of phospholipid concentration, chitosan concentration, and liposome size on the properties of the particles formed was determined. The particle size and charge (ζ-potential) were measured using dynamic light scattering and particle electrophoresis. The particle charge changed from –38 mV in the absence of chitosan to +60 mV in the presence of chitosan, indicating complex formation between the anionic liposomes and cationic chitosan molecules. Below a minimum critical chitosan concentration ( c _min), large aggregates were formed that phase separated within minutes, whose origin was attributed to formation of coacervates. On the other hand, above a maximum critical chitosan concentration ( c _max), large flocs were formed that sedimented within hours, whose formation was attributed to depletion flocculation. Minimum and maximum critical chitosan concentrations depended on liposomal concentration and size. At c _min < c < c _max, chitosan-coated liposomes were formed that did not aggregate and were stable to sedimentation. Coated liposomes had better stability to aggregation than uncoated liposomes when stored at ambient temperatures for 45 d. This study indicates that chitosan can be used to form biopolymer-coated liposomes with enhanced stability over uncoated liposomes.