The stabilizing behaviour of soybean soluble polysaccharide and pectin in acidified milk beverages

The mechanisms of stabilization of soybean soluble polysaccharide (SSPS) and high methoxyl pectin (HMP) in acidified milk drinks were studied focusing on the differences in behaviour between the two polysaccharides. The changes in casein micelles size during acidification with glucono-δ-lactone or by direct acidification were measured using light scattering. When HMP was added to skim milk before acidification, pectin adsorbed on the surface of the casein micelles via electrostatic interactions and prevented casein aggregation. Results suggested that adsorption of pectin occurred from the beginning of acidification and somewhat affected the rearrangement of casein micelles in the pH range between 5.8 and 5.0. On the other hand, SSPS, at concentrations up to 2% (w/w), did not interact with caseins at pH >4.6. At pH <4.2 SSPS showed better stabilizing properties than HMP. In addition, between pH 4.2 and 3.2, SSPS-stabilized acid dispersions were not affected by pH, while dispersions homogenized with pectin showed a size distribution that depended on pH. The differences in structure between SSPS and HMP account for the unique functionalities of the two polysaccharides in acid milk systems.     

水溶性豌豆多糖的提取及性能研究

为了提升豌豆加工副产物——豌豆粉渣的高值利用化,以豌豆粉渣为原料,系统研究了不同的提取条件对水溶性豌豆多糖(Pea soluble polysaccharide,PSPS)得率及功能特性的影响,同时对PSPS的分子量,不同p H条件下的Zeta电位和酸性条件下的粒度分布进行测定,以及对其微观结构进行观察分析。研究结果表明,豌豆多糖的最佳提取工艺为:固液比1∶20,中性淀粉酶添加量为0.24%,酶解时间为30 min;复合植物水解酶Viscozyme L添加量0.15%,酶解时间为30 min,除蛋白时间为30 min,p H 5.0,120℃高压1.5 h。在此条件下的PSPS得率可达10.43%且分散稳定性最优,其分子质量主要分布在252 k Da左右;在p H 3.5~11.0条件下,PSPS的电位绝对值高于水溶性大豆多糖(Soybean soluble polysaccharide,SSPS),接近于高酯果胶(High methoxyl pectin,HMP);在p H 3.6~4.6的环境中,PSPS粒度分布与SSPS相近。试验表明PSPS是一种类似于SSPS且具有分散稳定性的多糖。     

可溶性大豆多糖对酸性乳饮料稳定性影响的研究

该文主要研究可溶性大豆多糖（SSPS）对配制型酸乳及发酵型酸乳饮料稳定性的影响。通过测定酸性乳饮料的离心沉淀率,分别研究单一使用SSPS及SSPS、CMC和HMP复配后对配制型酸乳饮料稳定性的影响。同时,还研究了单一使用SSPS及SSPS和CMC复配后对发酵型酸乳稳定性的影响。结果表明,配制型酸乳最终pH值为3．9时,添加0．4％的SSPS或添加0．3％的SSPS和0．1％的CMC,具有良好的稳定性;正交试验结果表明,复合添加0．3％的SSPS、0．05％的CMC、0．4％的HMP配制型酸乳的稳定性较好;发酵型酸乳的最终pH值为4．0时,添加0.4％的SSPS或添加0．1％的SSPS和0．3％的CMC,具有良好的稳定性。     

粒径分析法研究稳定剂对含乳饮料稳定性的影响

研究水溶性大豆多糖(SSPS)、羧甲基纤维素钠(CMC)和高酯果胶(HMP)在含乳饮料中的粒径分布和离心沉淀率。结果表明：在SSPS、CMC和HMP的质量分数大于0.3%时,酸性含乳饮料的体系开始趋于稳定,当HMP添加量为0.3%、SSPS和CMC的添加量分别为0.5%时,含乳饮料体系稳定性最好,而且粒径分析与离心沉淀率结果相一致。通过分析含乳饮料的粒径分布和离心沉淀率可以快速、准确的判断所添加稳定剂的含量在含乳饮料体系中应用的可行性。     

Oxalic extraction of high methoxyl pectin and its application as a stabiliser

The objective of this work was to extract high methoxyl (HM) pectin with oxalic acid, characterise its physicochemical properties and evaluate its dispersion stability in acidified milk drink (AMD). HPSEC–MALLS analysis revealed that the obtained HM pectin was high in molecular weight (522.4 kDa). The ζ-potential of the obtained HM pectin in aqueous solution at pH 4.0 was −31.5 mV. The AFM images proved that the obtained HM pectin contained several long linear molecules. The apparent diameter of AMD stabilised by the obtained HM pectin was 636 nm at the concentration of 3.0‰. The stability analysis of AMD and the microscopic observation with confocal laser scanning microscopy (CLSM) proved that the obtained HM pectin was a prominent stabiliser in AMD.     

水溶性大豆多糖与大豆果胶的提取及功能特性研究进展

大豆作为我国传统作物,有很长的耕作历史,但由于国内对大豆的深加工起步较晚,对于深加工的副产物豆皮、豆渣的研究利用较不充分。而豆皮、豆渣中富含膳食纤维,是水溶性大豆多糖(soluble soybean polysaccharides,SSPS)和大豆果胶(soybean pectin,SP)的良好来源。SSPS和SP结构和性能相似,在食品工业中具有很高的应用价值。在国外,对SSPS和SP的研究较早,对SSPS和SP的提取工艺、分子结构组成、流变学性质、乳化性质以及稳定酸性乳饮料的机制等方面已经做了不少的研究。国内起步晚,SSPS和SP的工业化生产始终未成健全体系,SSPS及SP的提取工艺存在不成熟、提取纯度不高及功能性质不稳定等问题。本文对SSPS和SP的结构、生物活性、以及在食品工业中应用的研究进展进行了综述。     

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.     

Influence of environmental stresses on the physicochemical stability of orange oil bilayer emulsions coated by lactoferrin–soybean soluble polysaccharides and lactoferrin–beet pectin

Based on layer-by-layer electrostatic deposition, orange oil bilayer emulsions stabilized with lactoferrin (LF)–soybean soluble polysaccharides (SSPS) and lactoferrin (LF)–beet pectin (BP) were prepared. The effect of environmental stresses (ionic strength, pH, freeze–thaw and light) on the physicochemical stability of primary and secondary emulsions was investigated. In the absence of anionic polysaccharides, orange oil emulsion was highly unstable and aggregated at pH 7–9 and NaCl of 0.1–0.5 M. The droplets in LF–SSPS coated emulsion were stable against aggregation at pH range of 3–10 and NaCl concentration less than 0.3 M, while the droplets in LF–BP coated emulsion were stable against aggregation at pH 4–9 and NaCl concentrations of 0–0.5 M. All the primary and secondary emulsions showed the instability after the freeze–thaw treatment and the stability could be improved in the presence of maltodextrin. During the light exposure (0.35 W/m², 45 °C) for 8 h, the bilayer emulsions could protect key volatile compounds (decanal, octanal and geranial) from the oxidation compared with the primary emulsions. These results suggested that the layer-by-layer electrostatic deposition could improve the stability of LF-coated emulsion to environmental stresses.     

Thermal analysis of β-lactoglobulin complexes with pectins or carrageenan for production of stable biopolymer particles

Biopolymer nanoparticles can be formed by thermal treatment of electrostatic complexes of globular proteins and anionic polysaccharides. The purpose of this study was to provide insights into the physicochemical origin of biopolymer particle formation using differential scanning calorimetry (DSC) and temperature-scanning turbidity measurements. DSC measurements indicated that high methoxyl pectin (HMP), low methoxyl pectin (LMP) and carrageenan (C) had little impact on the thermal denaturation temperature of β-lactoglobulin (T_m ～ 78 °C) at pH 4.75, where electrostatic complexes are formed. Temperature scanning turbidity measurements indicated that extensive biopolymer aggregation occurred above T_m for β-lactoglobulin-pectin systems, but not for β-lactoglobulin-carrageenan systems. This difference was attributed to the greater strength of the attractive electrostatic interactions between the protein and carrageenan molecules, compared to the protein and pectin molecules. The biopolymer particles formed by heating β-lactoglobulin-pectin complexes were relatively stable to association/dissociation from pH 3 to 7 for HMP and from pH 4 to 7 for LMP, whereas the β-lactoglobulin-C complexes were highly unstable to pH changes. The β-lactoglobulin-pectin nanoparticles (d = 200–300 nm) may therefore be useful as natural delivery systems or fat replacers in the food, pharmaceutical, cosmetic and other industries.     

Micro- and nano-emulsions based on soluble soy polysaccharide and octenyl succinic anhydride modified soluble soy polysaccharide

In this study, emulsion stabilised by soybean soluble polysaccharide (SSPS) and octenyl succinic anhydride modified SSPS (OSA-SSPS) with high molecular weight (HM_W) at concentrations (2%, 3%, 4%, 5%, 6%) was prepared. The droplet size of emulsion stabilised by OSA-SSPS (HM_W) was between 150 and 300 nm with a single distribution peak and increased by 0.1 μm after 4 weeks; that of emulsion stabilised by SSPS was between 1 and 5 μm with two distribution peaks and increased by more than 2 μm after 4 weeks. The viscosity of emulsion with OSA-SSPS (HM_W) was larger than that with SSPS, and the absolute value of zeta potential of microemulsion with SSPS was lower than 43 mV while that of nanoemulsion with OSA-SSPS (HM_W) was higher than 46 mV. The stability of nanoemulsion with OSA-SSPS (HM_W) slightly varied with the increase of storage time and concentration, which provided theoretical guidance for the application of OSA-SSPS in nanoemulsion.     

Analysis of protein denaturation,and chemical visualisation,of frozen grass carp surimi containing soluble soybean polysaccharides

The mechanism of protein denaturation of frozen surimi enriched with soluble soybean polysaccharides (SSPS) was investigated. Near-infrared (NIR) and hyperspectral imaging (HSI) technology were used to predict protein denaturation. The fresh grass carp surimi was divided into four groups with SSPS additions of 0%, 1%, 3% and 5%, respectively, which were frozen and stored at −18 °C. Samples were examined after 0, 1, 2, 4 and 8 weeks, for salt-soluble protein content, total SH, NIR hyperspectral image and Raman spectrum features. The results showed that addition of SSPS decelerated protein degradation. After 8 weeks of storage, the 5% SSPS addition maintained the highest salt-soluble protein content, while for total SH, 3% and 5% SSPS addition had similar effect. Raman spectra illustrated that SSPS had the ability of maintaining an α-helix content, as well as decreasing the exposure of polar groups, and reducing the oxidation of SH group into disulphide bonds. NIR spectra showed that the overall reflectance of frozen surimi increased with the increase in SSPS. Two partial least squares regression (PLSR) models were established after pretreatment of HSI spectral statistics and selection of characteristic wavelengths. The distribution maps were finally generated based on the simplified PLSR models.     

高甲氧基果胶对酸性大豆蛋白体系的稳定机理

为揭示高甲氧基果胶对酸性豆乳体系稳定的作用机理,通过添加不同质量浓度果胶,研究在pH值由7.0～3.0降低过程中大豆蛋白的粒径、ζ-电位以及微观结构变化。结果表明：当体系pH＜6.0时,果胶通过静电作用吸附在大豆蛋白胶粒上,阻止了大豆蛋白颗粒在酸性状态的聚集。果胶质量浓度≤0.2 g/100 mL,质量浓度1.5 g/100 mL的大豆蛋白聚集,体系失稳;果胶质量浓度≥0.4 g/100 mL,质量浓度1.5 g/100 mL的大豆蛋白体系在一定pH值内稳定,果胶质量浓度越大,稳定性越好。酸性大豆蛋白体系的稳定性与大豆蛋白和果胶之间的静电吸附作用以及果胶质量浓度有关。     

从豆渣中提取水溶性大豆多糖的工艺优化研究

以豆渣为原料采用水热法提取大豆多糖,对固液比、温度、pH值、提取时间进行单因素试验,分析了各因素对粗多糖产率、还原糖含量、透明度、水溶性大豆多糖纯度的影响。采用4因素3水平正交试验对工艺进行优化,得到了优化的工艺条件。根据综合评分,选出最佳参数是：固液比1∶20（g∶mL）,温度110 ℃,pH 4.5,提取时间3 h,所得粗多糖产率52.4%,还原糖含量3.86%,透明度86.14%,多糖纯度69.88%。     

水溶性大豆多糖的微波浸提工艺优化

采用响应面分析法(response surface analysis,RSA)优化了微波浸提低温豆粕水溶性多糖的工艺条件。在单因素实验结果基础上,选取pH值、时间、料水比及微波功率4个因素进行中心组合旋转实验设计(central composite rotatable design,CCRD),并通过RSA对微波浸提水溶性大豆多糖工艺参数进行了优化组合。结果表明:在pH 8.0,料水比(g∶mL)1∶6,提取时间2.6 min,功率380W条件下,水溶性大豆多糖的得率可达5.86%,与验证实验相对误差为0.44%,证明响应面法优化结果是真实有效的。     

复合酶水酶法提取大豆蛋白的工艺优化

采用复合酶水酶法提取大豆蛋白。水解酶选用碱性蛋白酶,复合酶采用纤维酶、半纤维酶、果胶酶。得出最优复合酶水酶法提取大豆蛋白工艺条件为料水比1:6(g/mL)、纤维素酶添加量0.64%、半纤维素酶添加量0.56%、酶解pH5、酶解温度37℃条件下水解0.75h后,再利用Alcalase碱性内切蛋白酶,加酶量1.85%、酶解温度50℃、酶解pH9.26、水解3.6h。经过验证实验可知,在最优酶解工艺条件下总蛋白提取率可达到极大值即85.78%。经过复合酶酶解预处理比传统的湿热预处理的总蛋白提取率提高了近10%,其原因经分析是经过复合酶酶解处理的豆粉其细胞结构充分破坏,使得酶的作用位点暴露更有利于蛋白酶的作用,具体的机理分析有待进一步研究。     

Stabilization of acidic soy protein-based dispersions and emulsions by soy soluble polysaccharides

Soy soluble polysaccharides (SSPS) are shown to prevent destabilization of soy protein isolate (SPI) dispersions and SPI-based oil-in-water (O/W) emulsions under acidic conditions. Addition of SSPS above a critical concentration (0.25 wt%) increased the stability of 0.50 wt% SPI dispersions against aggregation and phase separation under conditions where SPI would normally precipitate (near its isoelectric point). Though SSPS neutralized SPI surface charge via electrostatic interaction, there was increased stability against aggregation due to steric repulsion. At acidic pH, addition of 1 wt% NaCl electrostatically screened protein–polysaccharide complexation which led to SPI precipitation and sedimentation. However, the order of salt addition had a significant impact on charge screening, with salt added before pH adjustment reducing SPI–SSPS complexation whereas it had less effect when added afterwards. Salt penetration efficacy diminished with decreasing pH. O/W emulsions (5 wt% oil) prepared with 0.50 wt% SPI destabilized at pH 4–5 due to protein aggregation, but addition of ≥0.25 wt% SSPS improved emulsion stability by inhibiting protein–protein interactions thus limiting increases in oil droplet diameter over time. Overall, both dispersion and emulsion stability greatly depended on pH, ionic strength and SSPS concentration. These results demonstrated that SSPS could effectively stabilize acidic SPI dispersions and that SPI–SSPS interactions may be used as a tool to improve the kinetic stability of SPI-based O/W emulsions.     

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.     

水溶性大豆多糖理化及黏度性质研究

目的以低温豆粕为原料,采用微波-超声波协同技术提取了水溶性大豆多糖(water-soluble soybean polysaccharide,SSPS),并对大豆多糖的部分理化性质,包括单糖组成、相对分子质量以及粘度性质等进行深入研究。方法分别采用气相色谱与高效凝胶色谱方法对SSPS的单糖组成、相对分子质量进行了测定,采用旋转式粘度计分析了大豆多糖质量浓度、离子强度、温度、pH对SSPS溶液粘度的影响。结果 SSPS的单糖组成主要为半乳糖,其次为葡萄糖、甘露糖、氨基半乳糖、阿拉伯糖等;SSPS的重均相对分子质量约274.752 k;SSPS的粘度随其质量浓度增加而显著增大,随温度、pH值的增加而减小,金属离子(Na+、Ca2+、K+)浓度的变化对其粘度的影响很小。结论本研究将为SSPS的潜在应用提供理论指导。     

Effects of chloride,thiocyanate and sulphate salts on β‐lactoglobulin–pectin associative complexes

Protein–polysaccharide complexes are used to improve protein stability and encapsulate high‐value ingredients, yet the influence of different salts on their formation has not been investigated. Using light scattering and turbidimetry, effects of chloride, sulphate and thiocyanate salts on β‐lactoglobulin and pectin complexes (protein/pectin ratio = 2:1 and 4:1) were determined in relation to effects of pH and ionic strength. Effects of anions on complex formation were significant at 25 mmol kg^?1 added ionic strength. Cation effects were not significant. At 100 mmol kg^?1 ionic strength, pH of complex formation increased with sulphate salts (pH 5.1) relative to chloride and thiocyanate salts (pH 4.9), while pH of coacervation increased with sulphate salts (pH 4.7) and decreased with thiocyanate salts (pH 4.4) relative to chloride salts (pH 4.6). Pure β‐lactoglobulin stability was otherwise reduced with thiocyanate salts below pH 5, implying a significant effect of pectin interactions.     

大豆蛋白酶解产物的微胶囊化及理化性质表征

令人难以接受的苦味和较强的吸湿性是限制大豆蛋白肽成为高品质食源肽的重要因素。本研究以大豆蛋白酶解产物(SPH)为芯材,以大豆蛋白(SPI)-大豆多糖(SPSS)复合物为壁材,通过喷雾干燥技术制备大豆蛋白酶解产物微胶囊,优化其工艺,并对微胶囊产品理化性质进行表征。结果表明,微胶囊的芯材/壁材比例为1/4,壁材比例(SPI/SPSS)为2/1,微胶囊具有最佳的大豆蛋白酶解产物包埋效果,包埋率达50.92%、苦味降低2.68倍、吸湿性降低1.61倍。透射电镜结果显示,微胶囊呈球型,表面光滑、连续,无孔洞或裂缝。红外分析结果证实SPI与SSPS之间发生了静电相互作用。大豆多糖与大豆蛋白因其大分子结构,组合使用能提升包埋的结构稳定性,也为SPH微胶囊产品作为功能性配料提供一定理论基础。