大豆多糖固体碱催化剂脱酯效果影响因素

为了研究固体碱催化剂对大豆多糖(SSPS)脱酯效果的影响,以商业高甲氧基大豆多糖(SSPS)为原料,利用固体碱MgO为催化剂,制备低酯化度的SSPS。研究反应温度、时间和催化剂投料质量比对SSPS脱酯效果的影响。脱酯效果通过产物相对分子质量、酯化度(DE)以及产物单糖组成等指标检验。结果显示,随着反应温度升高,产物SSPS的相对分子质量不断降低,酯化度不断降低,多分散性(PDI)逐渐增加;催化剂投料质量比从1∶100增加到1∶5,酯化度显著下降,但产物SSPS的相对分子质量和多分散性变化相对比较小,而进一步增加催化剂的投料质量比,所有指标均变化很小;反应时间的延长,产物SSPS的甲酯化度不断下降,多分散性也不断增加,且越到反应后期,酯化度下降越慢。单糖组成结果表明,固体碱MgO催化SSPS脱甲酯过程,侧链上中性糖被脱除最快,主链断裂和脱酯几乎是同步的,但聚阿拉伯糖和聚半乳糖侧链本身降解要比主链降解缓慢。与碱法脱酯工艺相比,在达到相似的酯化度前提下,MgO固体碱催化脱酯工艺产物具有更高的相对分子质量、更低的多分散性以及更好的产物颜色。上述结果说明MgO脱酯工艺在未来SSPS脱酯实际生产中可能有着良好应用前景。     

小米粉RVA糊化特性的研究

采用快速粘度分析仪（Rapid Viscosity Analyser,RVA）测定了在不同浓度、pH及添加蔗糖、食盐、明矾、硬脂酸等条件下小米糊RVA粘度曲线的变化情况,研究了小米淀粉粘度性质及其影响因素。结果显示,浓度对小米糊粘度性质影响显著,随浓度的增高,糊化温度降低,粘度曲线中峰值粘度及最终粘度升高;pH值对小米糊粘度性质影响较大,过高或过低的pH都会导致峰值粘度降低;随蔗糖添加量的增加,糊化温度略有增高;随着氯化钠浓度的增加糊化温度升高,氯化钠可提高小米糊粘度;明矾对小米糊的峰值粘度影响较大,而对糊化温度影响不大;添加硬脂酸的小米糊的最终粘度显著提高,而峰值粘度变化较小。通过研究为进一步了解小米淀粉的粘度特性及产品开发提供理论依据。     

动态高压微射流技术对可溶性大豆多糖结构的影响

研究动态高压微射流技术(DHPM)处理对可溶性大豆多糖(SSPS)组分、相对分子质量、外观形态及单糖组成的影响。结果表明：经DEAE-Cellulose 离子交换从大豆粗糖中纯化得到SSPS-1 和SSPS-2 两个组分,高效凝胶渗透色谱(HPGPC)分析表明SSPS-1为含少量蛋白的杂多糖,SSPS-2为高结合蛋白含量的单一多糖;SSPS-1经DHPM处理后,相对分子质量由7.33 × 105 减少至5.11 × 105;电镜扫描观察其形貌由针状排列结构变成末端膨大呈球形的“火柴棒”状有序排列结构;气相色谱分析单糖组成表明：SSPS-1 主链中单糖L- 鼠李糖和D- 半乳糖醛酸的含量分别降低9.4%、17.1%,侧链部分的单糖L- 阿拉伯糖、D- 半乳糖、D- 岩藻糖、 甘露糖分别降低14.3%、26.3%、41.7%、60%,而D- 木糖、D- 葡萄糖、葡萄糖醛酸未检出。     

大豆多糖对乳清分离蛋白—乳状液稳定性与流变特性的影响

本文研究了大豆多糖(SSPS)与乳清分离蛋白(WPI)乳状液静电组装,形成乳状液聚集体,考察了不同浓度的SSPS对WPI-乳状液稳定性与流变特性的影响,以期提高体系的粘弹性,形成高流变特性的食品体系。将不同浓度的大豆多糖与2%乳清分离蛋白乳状液(油相为20%)静电组装,分析乳状液的粒径,Zeta-电位,稳定性指数,流变性质和微观结构。结合剪切流变与微流变技术,深入研究了SSPS对乳清分离蛋白(WPI)乳状液流体特性与结构的影响。结果表明:随着SSPS浓度的增加,WPI乳状液的粒径在添加0.25%SSPS时达到峰值(3350±0.35)nm,而后随着SSPS浓度的增加而降低;Zeta-电位绝对值呈递减的趋势,表明SSPS与WPI间产生静电吸附作用;SSPS静电吸附提高WPI乳状液的稳定性;剪切流变结果表明,SSPS浓度为0.5%时,其粘度最大,并在剪切速率为95.8 s-1处其粘度是WPI乳状液粘度的10倍以上;微流变结果表明,0.5%SSPS-WPI乳状液的MSD曲线出现平台区,表明其弹性指数(EI)与宏观粘度指数(MVI)均显著提高达到最大值。微观结构结果表明,0.5%SSPS-WPI乳状液形成均一的乳状液聚集体。本研究将有助于理解大豆多糖与蛋白质乳状液的相互作用,同时为低脂高流变特性的食品(如蛋黄酱、调味汁、巧克力和植脂奶油等)生产提供理论指导。     

库拉索芦荟多糖的分离、纯化及其理化性质

以库拉索芦荟鲜叶为原料,从其去皮后的凝胶中提取得到芦荟多糖(AGP),采用硫酸铵沉淀法进行分级纯化,得到一个主要级分AGP40。分别采用高效凝胶渗透色谱法、比色法和离子色谱法对AGP40的纯度及分子质量、化学成分和单糖组成进行分析。利用红外光谱技术表征AGP40的光学特性,用旋转流变仪测定其表观黏度。结果表明:AGP40为均一性高的中性多糖,相对分子质量为338 ku,几乎不含糖醛酸和蛋白质,主要由甘露糖组成,含少量的葡萄糖。红外光谱图显示:AGP40含有乙酰基团,其乙酰基含量达29.9%,推测该多糖为乙酰化的葡甘露聚糖。此外,流变学实验显示:该多糖溶液表观黏度随浓度增加而增加。当质量浓度达到4%以上时,呈假塑性流体性质。     

亚临界水提取的水溶性大豆多糖的流变特性

采用亚临界水提取大豆多糖,并研究大豆多糖质量浓度、金属离子浓度、pH值、蔗糖添加量对水溶性大豆多糖水溶液流变性及其黏度的影响。结果表明：水溶性大豆多糖水溶液为假塑性流体,其流体类型不随大豆多糖质量浓度、pH值的变化和金属离子、蔗糖的添加而改变;金属离子对水溶性大豆多糖的黏度影响很小,而水溶性大豆多糖的黏度随其质量浓度、蔗糖添加量及pH值的增大而上升,但与果胶相比黏度仍较低。采用亚临界水提取的大豆多糖具有稳定的流变特性,可作为添加剂应用于低黏度乳酸饮料和含糖饮料等食品中。     

藻酸丙二醇酯的流变学特性研究

利用MCR101流变仪研究了质量分数、pH、蔗糖、NaCl、温度对藻酸丙二醇酯(PGA)流变学特性的影响。结果表明:藻酸丙二醇酯溶液是假塑性流体,其流动特性符合Power-law模型,其粘度随PGA质量分数和蔗糖浓度的增加而升高;随剪切速率、pH、温度的增加而降低;在较低NaCl浓度下(0.01和0.1mol/L),PGA溶液粘度降低,NaCl浓度在1mol/L时,溶液粘度增加。PGA溶液具有一定的触变性和粘弹性,在低频率区域体系以粘性为主,高频率区域体系以弹性为主,G′和G″的交点受PGA浓度、pH和温度的影响。     

大豆分离蛋白-水溶性大豆多糖可食性复合膜的制备与性质

以大豆分离蛋白(soy protein isolates,SPI)和水溶性大豆多糖(soluble soybean polysaccharides,SSPS)为主要原料进行了可食性复合膜的制备与性质研究。综合考虑SPI与SSPS的比例、甘油、海藻酸钠添加量及钙离子浓度等影响因素,通过单因素与正交实验对成膜配方进行研究,得到了复合膜的最佳配比,并从水溶性、水蒸气透过性、抗拉伸强度、断裂延伸率等方面对膜的性质进行了综合评价。结果显示:在SPI∶SSPS质量比为1∶7,甘油添加量2%,海藻酸钠添加量4%,Ca2+浓度为1.0mol/L的条件下,复合膜的综合性能评分最高,为67.8。     

不同分子量葡聚糖与大豆7S蛋白混合凝胶的流变学性质

采用哈克流变仪对不同分子量葡聚糖与大豆7S蛋白混合体系的凝胶流变学性质进行研究。结果表明:葡聚糖与大豆7S蛋白混合体系形成的蛋白多糖凝胶相对单一浓度的大豆7S蛋白凝胶具有较高的弹性模量;同分子量的葡聚糖与大豆7S蛋白混合体系形成的蛋白多糖凝胶黏弹性质随葡聚糖浓度增加而增加;同浓度葡聚糖与大豆7S蛋白混合体系形成的蛋白多糖凝胶黏弹性质随加入葡聚糖分子量的增加而增加;同浓度同类型葡聚糖体系凝胶形成的起始温度Tp0.25相似文献   

三种不同来源大豆分离蛋白流变性质的比较

为了了解加工工艺、pH值等因素对大豆分离蛋白的功能性质的影响,本试验研究了温度和pH值等外界条件分别对氧化大豆分离蛋白(ESR)、低脂质含量大豆分离蛋白(LRSP)和市售大豆分离蛋白(CSPI)三种蛋白的流变性质的影响。温度或pH值升高时,三种蛋白的粘度随剪切速率的增大而降低的速度加快,ESR变化显著,LRSP、CSPI发生变化,但CSPI整体粘度低于前两者。初步的试验结果表明,实验室生产的ESR和LRSP质量明显优于市场上购买的CSPI。     

制造过程对可溶性大豆多糖结构和产物起泡性的影响

通过控制酸水解、碱脱酯和蛋白酶解条件探讨可溶性大豆多糖制造过程对于产物结构和起泡性的影响。可溶性大豆多糖(SSPS)的结构采用单糖组成、重均分子量、酯化度、蛋白含量进行表征,起泡性用泡沫膨胀率(FE)和泡沫稳定性(FS)表征。结果表明,酸水解过程会破坏SSPS主链结构进而使分子量逐渐降低,但不影响酯化度和蛋白质含量;随着分子量的降低,SSPS的FE逐渐增大,但FS逐渐降低。碱脱酯过程不影响产物分子量,但可以使酯化度和蛋白含量同步降低,产物的FE和FS也同步下降。将低分子量高甲酯含量SSPS采用蛋白酶水解,获得具有相同分子量和酯化度、不同蛋白质含量的SSPS。起泡性结果显示随着蛋白含量的下降,SSPS的FE和FS均同步下降。上述结果说明,相比于酯化度,蛋白质含量和分子量对大豆多糖的起泡性具有更为重要的作用。     

抗坏血酸对猴头菇β-葡聚糖表观黏度及结构特征的影响

采用碱提醇沉法制备猴头菇β-葡聚糖(Hericium erinaceus alkali-extracted polysaccharide,HEAEP),系统研究了不同条件(抗坏血酸浓度、金属离子、温度、pH值等)下抗坏血酸对HEAEP表观黏度的影响,并深入分析了抗坏血酸对HEAEP结构特征的影响。研究结果表明:猴头菇β-葡聚糖表观黏度与抗坏血酸浓度存在依赖性,当抗坏血酸质量分数超过0.10000%时,抗坏血酸浓度越高,降解效果越差;金属离子(Cu²⁺、Fe²⁺)的加入会进一步促进抗坏血酸对HEAEP表观黏度的降解作用;而温度的影响相对较小;pH值和作用时间也有一定影响,当pH值为4,作用时间为12 h时,抗坏血酸对HEAEP降解效果最好。此外,抗坏血酸能降低HEAEP分子质量,但对HEAEP糖苷键类型及比例、单糖组成和特征官能团等结构特征影响较小。抗坏血酸降低猴头菇β-葡聚糖表观黏度的效果受到多重因素的影响,其中抗坏血酸浓度、Cu²⁺、Fe²⁺等影响较大,但作用前后的多糖主要结构特征变化相对较小。研究结果旨在为抗坏血酸与β-葡聚糖共存食品的生产提供理论参考。     

Extraction and characterisation of pectin polysaccharide from soybean dreg and its dispersion stability in acidified milk drink

In this study, pectin polysaccharide (SDPP) was obtained from soybean dreg (26.2% yield), and characteristics of SDPP were compared with those of soybean soluble polysaccharides (SSPS) and citrus pectin (HMP). The galacturonic acid and molecular weight of SSPS, SDPP or HMP were 11.8%, 40.6% or 70.2% and 112, 446, or 440 kDa. SDPP had similar viscosity and protein content to SSPS, and functional groups and linear structure to HMP. SSPS, SDPP or HMP differed in particle size of 260, 467 or 1195 nm and ζ–potential of −5.8, −14.6 or −23.5 mV at pH 4.0. The precipitation of acidified milk drink (AMD) was 6.31% without stabiliser or below 1.75% with 0.4% SDPP at pH 3.6–4.6. These results suggested that SDPP combines the structure and characteristic of HMP and SSPS, and AMD with SDPP had great stabilising behaviour at wider pH range (pH 3.6–4.6).     

葛仙米多糖理化性质和流变学特性的研究

为研究葛仙米多糖的流变学特性,以室内培养的葛仙米为原料,通过水提醇沉法得到葛仙米多糖;采用MCR-302型旋转流变仪考察质量浓度、酸碱性、温度、V_C和H₂O₂对多糖溶液表观黏度的影响,探究多糖溶液在扫描频率范围内的动态黏弹性,来反映其流变学特性。结果表明:其多糖含量为96.95%、重均分子量为1.324×105 Da、由阿拉伯糖、半乳糖、葡萄糖、木糖、甘露糖及葡萄糖醛酸组成;葛仙米多糖溶液是假塑性非牛顿流体,具有剪切稀释的特性;溶液黏度随质量浓度的增大而增加;在20~80℃内,溶液黏度随着温度的升高而降低;溶液pH=3.0和pH=11.0时的黏度小于pH=7.0;V_C和H₂O₂可以降低多糖溶液的黏度;在扫描频率0.1~10 Hz内,储能模量(G')和损耗模量(G″)随葛仙米多糖溶液质量浓度的增加而增大。此外,葛仙米多糖与透明质酸具有协效增稠性。     

超声波协同过氧化氢氧化法制备低分子质量大豆多糖

以大分子质量的大豆多糖为原料,探讨制备低分子质量可溶性大豆多糖的降解方法及工艺。通过初步对比超声波法、过氧化氢法和超声波协同过氧化氢氧化降解法,发现超声波协同过氧化氢氧化法降解效果最好。继而对这一降解方法进行了单因素和正交试验研究,研究结果表明:在超声波功率100 W的条件下,大豆多糖超声波协同过氧化氢氧化降解法的最佳工艺为过氧化氢浓度8%,70℃降解1.5 h,大豆多糖的分子质量可以由1.6×105降解到1.09×104。     

Characterisation of soy extract processed under different drying methods and extraction conditions

Soybean extract (SE), enriched in soy soluble polysaccharide (SSPS), was evaluated in three different conditions varying in extraction temperature and drying process: SE‐A ?80 °C, freeze‐dried, SE‐B ?80 °C, spray‐dried, SE‐C ?95 °C, spray‐dried. Spray‐dried SE presented lower moisture content, smaller and more uniform particles. In addition, zeta potential showed the same negative surface charge for all extracts showing the prevailing behaviour of SSPS. Moreover, all biopolymers were composed of three main molecular weight (Mw) fractions, but the Mw distribution was different between the three ingredients, reflecting their rheological behaviour in aqueous solution. Higher mean Mw led to enhanced apparent viscosity observed in neutral and acid pH for SE‐A, followed by ‐B and ‐C, respectively. The inverse behaviour was observed for intrinsic viscosity at neutral pH. However, SE‐C showed lower intrinsic viscosity at acid pH, which was attributed to protein–polysaccharide interaction presents in the solution.     

Characterization and functional properties of soybean high-molecular-mass polysaccharide complex

Soybean soluble polysaccharide (SSPS), extracted from the by-product obtained during isolation of soybean protein, is an anionic polysaccharide that stabilizes milk proteins under acidic conditions. We developed a high-molecular-mass complex of SSPS cross-linked via phosphate (SSPS-HC; absolute molecular weight = 2850 kg/mol, radius of gyration = 106 nm), and found that it has different protein stabilization properties when compared with the original SSPS (absolute molecular weight = 550 kg/mol, radius of gyration = 36 nm). The objective of this work was not only to study the rheological properties of SSPS-HC, but also clarify its protein-stabilizing properties in comparison with SSPS; if molecular mass or negative charge affected protein dispersion. Irrespective of high-molecular-mass, SSPS-HC possessed similar rheological properties to SSPS such as low viscosity in aqueous solution. The absolute negative charges of SSPS-HC measured by a zeta potential analyzer at pH range of 2.0–7.0 were higher than those of SSPS. Acidified milk drinks prepared with 8.4% non-fat milk solids and 0.4% SSPS-HC or SSPS showed low viscosity and small protein particle size, and did not aggregate for 14 days. The thickness of the hydrated layer, which was formed on the surface of protein particles by SSPS molecules measured after hemicellulase treatment with DLS (dynamic light scattering), was estimated to be about 89 nm for SSPS-HC and 33 nm for SSPS. These numerical values were in good relation to the molecular diameter of SSPS-HC and SSPS in aqueous solution measured by DLS and AFM image, and suggested that protein particles were dispersed and the hydrated monolayer made on the surface of protein particles by SSPS-HC or SSPS molecules prevented aggregation. However, stabilizing pH ranges were different with stability of SSPS-HC at pH range of 4.0–4.8 and stability for SSPS at pH range of 3.6–4.2. In addition to the difference in the molecular mass and absolute negative charge, the phosphate groups of SSPS-HC were possibly influenced on the protein-dispersing property approximately at isoelectric point of milk protein; SSPS-HC prevent aggregation of casein by accelerating solubility of calcium phosphate under acidic conditions as is already reported in the starches phosphorylated.     

水溶性大豆多糖的分子表征和溶液流变学性质

采用核磁共振方法和凝胶渗透色谱（gel permeation chromatography,GPC）技术测定了水溶性大豆多糖（soluble soybean polysaccharides,SSPS）的酯化度和分子质量,并研究了SSPS在水溶液中的分子构象和流变学性质。结果表明,核磁共振方法可以快速准确地测定SSPS的酯化度,水溶液中SSPS呈紧密的无规线团构象,具有很低的本征黏度,SSPS水溶液表现出很强的剪切变稀行为,并具有明显的触变性。     

Soy soluble polysaccharide stabilization at oil–water interfaces

Soybean soluble polysaccharide (SSPS) is obtained from the by-product of the production of soy protein. SSPS has been employed as a functional ingredient in numerous food applications. When used to prepare oil-in-water emulsions, SSPS forms thick, stable interfaces in a wide pH range, in both acidic and neutral conditions. SSPS forms stable interfacial layers at relatively low biopolymer concentrations (about 4% (w/w) in 20% (w/w) oil-in-water emulsions), and although rich in galacturonic acid, its functionality does not seem to be affected by varying concentration of cations. This work describes the emulsifying properties of SSPS and its stability under various environmental conditions and the principles that regulate the stabilization behavior of this polysaccharide. SSPS contains a high molecular weight polysaccharide fraction with interfacial properties and a small molecular weight fraction. A polypeptide fraction, with an estimated molecular mass of 50 kDa, is covalently linked to the SSPS backbone chains and acts as an anchor to the oil–water interface. The carbohydrate moieties of the SSPS stabilize the emulsion droplets via steric interactions, forming a thick (ranging between 15 and 30 nm, depending on the SSPS type), hydrated layer on the surface of the oil droplet.