Emulsifying properties of pea protein/guar gum conjugates and mayonnaise application

Modified plant protein may be used as a healthy and more functional emulsifier in food products. The objective of this study was to evaluate the emulsifying properties of functionally enhanced pea protein (i.e. pea protein conjugated with guar gum, G-PPI) and its potential application to mayonnaise, compared with unmodified pea protein. Emulsions containing G-PPI were prepared at different pH, salt concentrations, protein concentrations and oil/water ratios. Mayonnaise samples were prepared using the pea proteins or egg yolk powder. Various characteristics of the emulsions, including droplet size, apparent viscosity, viscoelasticity and microstructure, were analysed. The emulsions with G-PPI had significantly increased stability of up to 89.4% and apparent viscosity of up to 48.62 mPa.s. The G-PPI emulsion had a smaller average droplet size of 934.4 nm at pH 7 compared with the PPI emulsion (stability 62.7%, apparent viscosity 22.8 mPa.s and droplet size 1664.8 nm). The pH, NaCl concentration, protein concentration and oil/water ratio greatly affected the emulsifying properties. The G-PPI mayonnaise at higher protein concentrations (6 or 8%) exhibited excellent emulsifying and rheological properties. The modified pea protein through the green modification process with natural polysaccharides could be used as a safe and functional emulsifier in different emulsified foods.     

Characterization of Phase Separation Behavior, Emulsion Stability, Rheology, and Microstructure of Egg White–Polysaccharide Mixtures

ABSTRACT:  Phase separation behavior of egg white-pectin/guar gum mixtures was investigated. These systems led to phase separation arisen by either depletion flocculation or thermodynamic incompatibility. The influence of polysaccharides on the emulsifying activity index (EAI), emulsifying stability index (ESI), creaming stability, microstructure, and rheological properties was also studied at different polysaccharide concentrations (0% to 0.5%, [w/v]). Increasing pectin and guar gum concentration from 0.01% to 0.5% significantly improved EAI by 51% and 25%, respectively. The highest ESI and EAI values were obtained in the presence of 0.5% (w/v) pectin/guar gum. Microscopic images showed that emulsions containing polysaccharides had small droplets as compared to that of emulsions without polysaccharides. The addition of polysaccharides improved emulsion stability against creaming. Egg white-stabilized emulsions with and without polysaccharides reflect the pseudoplastic behavior with  n  < 1.0. Polysaccharides, especially at high concentrations, affected the viscoelastic behavior of the emulsions; storage ( G ') and loss modulus ( G ") crossed-over at lower frequency values as compared to that of emulsions containing no polysaccharide.     

兔皮胶原蛋白的加工特性

以兔皮胶原蛋白为原料,对其加工特性进行系统研究。结果表明,兔皮胶原蛋白具有较强的吸水性,达到14.89 m L/g;其在酸性环境中有很高的溶解性,在p H值为3时,溶解度最高,在碱性环境中溶解度降至50%左右;离子质量浓度对胶原蛋白的溶解度有明显影响,其在Na Cl质量浓度为0~2 g/100 m L时保持相对稳定,在Na Cl质量浓度由2 g/100 m L增加至4 g/100 m L过程中急剧下降,而Na Cl质量浓度大于4 g/100 m L后,胶原蛋白溶解度变化不再明显;当胶原蛋白的质量浓度小于1 g/100 m L时,兔皮胶原蛋白的乳化性随着胶原蛋白质量浓度的增加逐渐增加,但质量浓度超过1 g/100 m L时,乳化性降低,乳化稳定性随胶原蛋白质量浓度的变化呈现与乳化性相反的趋势;低质量浓度的胶原蛋白溶液在p H 3~6过程中,乳化性和乳化稳定性均呈下降趋势,随后,p H 6~9时乳化性和乳化稳定性缓慢增加后保持稳定;离子质量浓度在0.00~7.02 g/100 m L范围内,随离子质量浓度的增加,乳化性呈现出先升高后降低的趋势,而乳化稳定性则呈现先增加随后保持稳定的趋势,在离子质量浓度为5.85 g/100 m L时,胶原蛋白的乳化性与乳化稳定性较好。     

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.     

不同NaCl浓度条件下亚麻籽胶对肌原纤维蛋白凝胶作用力及乳化特性的影响

为改善低盐肉制品凝胶乳化品质的降低,明确亚麻籽胶（flaxseed gum,FG）添加对肉制品品质的影响,以肌原纤维蛋白（myofibrillar protein,MP）为研究对象,通过测定乳析指数、电位值、粒径、显微观察研究不同NaCl浓度条件下FG对MP乳液乳化稳定性的影响,而化学键的测定显示FG对MP凝胶化学作用力的影响。结果表明,形成MP凝胶及FG-MP凝胶体系的关键是二硫键和非二硫共价键的贡献;不同NaCl浓度对FG-MP乳液的乳析指数、ζ-电位、粒径的影响均不显著（P＞0.05）,而MP乳液随着NaCl浓度的提高,乳化稳定性、ζ-电位、粒径均显著变化（P＜0.05）。特别是在低浓度NaCl条件下,FG的加入可以显著提高MP乳液的稳定性（P＜0.05）。显微观察发现加入FG可以改善MP乳液液滴聚集的现象。因此,说明在低浓度NaCl条件下加入FG可以显著提高肌原纤维蛋白乳液的乳化稳定性,提高其抗盐能力,促进亚麻籽在肉制品中的应用。     

Stabilization of multilayered emulsions by sodium caseinate and κ-carrageenan

The influence of the κ-carrageenan concentration and pH on the properties of oil-in-water multilayered emulsions was studied. Multilayered emulsions were prepared by the mixture of a primary emulsion stabilized by 0.5% (w/v) sodium caseinate (Na-CN) with κ-carrageenan solutions with different concentrations (0.05–1% w/v). The emulsions were evaluated at pH 7 and 3.5. At pH 7, there was little adsorption of κ-carrageenan onto the droplet surface and a depletion flocculation was observed when the polysaccharide concentration exceeded 0.5% (w/v). At pH 3.5, a mixed κ-carrageenan–Na-CN second layer was formed around the protein-covered droplets and the emulsions showed bridging flocculation at lower polysaccharide concentrations (0.05–0.25% w/v). Stable emulsions could be formed with the highest κ-carrageenan concentration (1% w/v) at both pH values (7.0 and 3.5). Thus, stable emulsions were successfully produced using protein–polysaccharide interfacial complexes, and the oil droplet diameter, zeta potential and rheological properties of these emulsions were not affected by changes in the pH.     

Emulsion properties of pork myofibrillar protein in combination with microbial transglutaminase and calcium alginate under various pH conditions

In this study, the effects of microbial transglutaminase (MTG) and calcium alginate (CA) systems in combination with soybean oil on the emulsion properties of porcine myofibrillar protein (MP) were evaluated under various pH conditions. MTG was shown to improve emulsifying capacity and creaming stability, which increased with increasing pH values up to 6.5. The CA did not influence emulsifying capacity, but it improved the creaming stability of the MP-stabilized emulsions. Both MTG and CA enhanced the rheological properties, but their effects on the physical characteristics of the protein evidenced an opposite trend in relation to pH, i.e., the MTG system improved both the emulsion and gelling properties with increasing pH, whereas the CA system was effective when the pH was lowered. By combining the two MP gelling systems, a stable and pH-insensible emulsion could be produced.     

水相pH和Na+对微晶纤维素与猪油的Pickering乳液稳定性的影响

考察水相pH和Na+浓度对微晶纤维素（MCC）和猪油形成的Pickering乳液稳定性的影响。分别将不同pH和含有1% MCC的不同Na+浓度的水相与等体积的油相混合、制备MCC-猪油Pickering乳液,分析不同水相pH（pH4~9）和不同Na+浓度（0~500 mmol/L）条件下,乳液的外观结构、乳析指数、微观结构、粒径、Zeta电位以及乳液流变特性的变化。结果表明,在pH5~8条件下,MCC-猪油Pickering乳液均未出现明显分层现象,且乳析指数未发生变化,乳滴粒径小于pH4和pH9条件,具有更好的黏度和抗剪切能力,其中,在pH6条件下表现出最好的稳定效果。当Na+浓度在300 mmol/L及以上时,随着静置时间的延长,乳液稳定性下降的越快;Na+浓度为400 mmol/L时,乳液静置3 d会出现分层现象。随着Na+浓度的升高,静电屏蔽作用使得乳液颗粒粒径不断增大,Zeta电位绝对值降低,黏度和抗剪切能力下降。中低pH（pH5~8）水相及低Na+浓度（≤300 mmol/L）水相条件下MCC-猪油Pickering乳液具良好的乳化稳定性,但pH4和pH9及高Na+浓度（>300 mmol/L）水相条件下乳液的稳定性欠佳。探讨不同pH和Na+浓度条件对MCC-猪油Pickering乳液乳化稳定性的影响及其原理,为其在功能性预乳化肉制品的加工与应用提供一定参考。     

不同黏度多糖阿拉伯胶和瓜尔胶对肌原纤维蛋白乳化性质的影响

选取两种分子质量相近、黏度相差较大的天然高分子多糖阿拉伯胶（arabic gum,AG）和瓜尔胶（guar gum,GG）分别与肌原纤维蛋白（myofibrillarprotein,MP）进行复合,研究不同多糖添加量（0.1%～0.5%）对MP-多糖复合物乳液性质的影响规律。结果表明,AG和GG均可以显著改善MP的乳化性质,其中AG对乳化活性的改善效果较好,而GG更有利于乳液的稳定性。随着多糖质量分数增加,乳化活性指数和稳定性指数均呈先升高后降低趋势,AG和GG添加量分别为0.3%和0.2%时,乳化活性指数和稳定性指数达到最大值。界面蛋白含量测定结果显示,AG和GG均会导致界面蛋白含量下降,尤其是GG的作用更明显。随着AG和GG添加量增加,乳液粒径逐渐减小,且尺寸分布更加均一,添加量超过0.3%后,GG组乳液出现少量絮凝现象。同一添加量下,GG组乳液粒径明显小于AG组。流变学分析证实,所有乳液均为假塑性流体,表现出弱凝胶性质。AG添加量较少（≤0.3%）时会降低乳液黏度,并明显提高乳液的储能模量,而GG的添加使乳液表观黏度和储能模量均显著提高,与AG相比,高黏度GG制备的乳液拥有更高的...     

基于三种多糖与酪蛋白复配制备W/O/W型乳液及其包封红景天苷效果的研究

为提高红景天苷稳定性及口服吸收效果,本研究以红景天苷为内水相,含聚甘油蓖麻醇酯的菜籽油为油相,分别采用葡聚糖、壳聚糖和大豆多糖混合酪蛋白作为外水相,制备W/O/W型多重乳液。研究了不同浓度的三种多糖对多重乳液的微观结构、粒径、电位、贮藏稳定性、乳化性、包埋率、载药量和体外消化过程的影响。结果显示,相比于酪蛋白对照组、壳聚糖-酪蛋白组和大豆多糖-酪蛋白组,葡聚糖-酪蛋白W/O/W型多重乳液稳定性最好。高浓度的葡聚糖能够明显提升葡聚糖-酪蛋白多重乳液的贮藏稳定性,当葡聚糖添加量为1.2%时,多重乳液平均粒径最小,可达623.03±5.21 nm（P<0.05）;电位绝对值最高（P<0.05）,平均电位为?37.3±0.46 mV;对酪蛋白乳化性质提升最大（P<0.05）;对红景天苷的包埋率最高（P<0.05）,可达92.8%,载药量为162.89±4.21 μg/g。模拟消化研究发现葡聚糖-酪蛋白多重乳液不仅能有效地保护红景天苷,还能够靶向地在模拟肠道内传递和释放,葡聚糖添加量为1.2%的葡聚糖-酪蛋白负载体系的稳定性和控释效果最佳。该研究结果可为红景天苷在食品和医药中的应用提供理论支撑。     

Manipulating interfacial behaviour and emulsifying properties of myofibrillar proteins by L-Arginine at low and high salt concentration

The present work examined the impact of L-Arginine (Arg) on the emulsifying properties, interfacial behaviour and conformational characteristics of myofibrillar proteins (MPs) at high (0.6 m ) and low (0.15 m ) salt concentration to maintain good emulsifying properties of MPs at low salt concentration. The data indicated that Arg increased the emulsifying activity index/emulsion stability index (EAI/ESI) and decreased the CI and droplet size of emulsions regardless of salt concentration. Raman spectra revealed that the α-helix content decreased from 60.30% to 51.26% at high salt concentration, and from 60.20% to 54.82% at low salt concentration in the presence of Arg. In addition, MPs treated with Arg exhibited a higher interfacial pressure and more rapidly diffusion to the oil surface. Meanwhile, Arg increased the interfacial protein loading. The results demonstrated that Arg caused the unfolding of MPs, promoting the adsorption of proteins and decreasing the interfacial tension, ultimately improving the stability of emulsions at low salt concentration.     

乳清分离蛋白聚集体乳化性能及其Pickering乳液稳定性

以乳清分离蛋白（whey protein isolate,WPI）为原料,分别在pH 2.0和pH 7.0条件下,85 ℃加热12 h制备2 种不同形态的蛋白质聚集体,研究2 种聚集体微观形貌的特征以及不同pH值和盐离子浓度下的乳化性能;采用透射电镜、动态光散射、光学显微镜等技术手段,探究WPI与2 种聚集体稳定的Pickering乳液微观结构、盐离子稳定性和热稳定性。结果表明：WPI分别在pH 2.0和pH 7.0且高温加热条件制得2 种微观形貌截然不同的蛋白聚集体（纤维状聚集体和球状聚集体）,并且2 种蛋白聚集体相较于WPI等电点均发生偏移,在不同pH值或盐离子浓度环境下,乳化性能均提高。2 种聚集体所稳定的Pickering乳液对不同pH值、盐离子浓度环境下有更好的稳定性,球状聚集体所稳定的Pickering乳液具有更好的热稳定性。这也为WPI聚集体稳定的Pickering乳液在乳饮料中的应用奠定基础。     

ENZYMATICALLY AND CHEMICALLY MODIFIED ZEIN FOR IMPROVEMENT OF FUNCTIONAL PROPERTIES

Limited specific hydrolysis of zein by trypsin was used to produce 1.42%, 1.70%, and 1.87% hydrolysates (percentage of peptide bonds cleaved), containing three to four polypeptides (by Fast Protein Liquid Chromatography (FPLC)) ranging in size from ～16,000 to 3,500 daltons. The mixtures of polypeptides had substantially increased solubilities at pH below 11, including at the isoelectric point of zein (pH 6–7). In general, the emulsifying activity index was less for the hydrolysates than for native zein; the emulsion stability was higher for the 1.70% hydrolysate than was the emulsion of native zein only at pH above 8. At lower pHs, the stability of the emulsions was similar for all samples. The foamability (% overrun) of the hydrolysates was higher than for native zein; the foam stability was higher for the 1.87% hydrolysate than for the other hydrolysates. Phosphorylation and deamidation of the hydrolysates markedly increased the water solubility in the pH range from 4 to 10. Chemical modification of the native zein improved the solubility at pH 2 to 9 after phosphorylation and pH 6 to 11 after deamidation as compared to the native protein. In general, the emulsifying activity index, as well as its stability, was less for the phosphorylated and deamidated hydrolysates than for native zein but the emulsifying activity index of deamidated native zein was higher at pH 7 to 11. Foaming activity and stability of chemically modified hydrolysates were similar to the 1.87% hydrolysate.     

Effect of medium molecular weight xanthan gum in rheology and stability of oil‐in‐water emulsion stabilized with legume proteins

Xanthan gum is a water‐soluble extracellular polysaccharide that has gained widespread commercial use because of its strong pseudoplasticity and tolerance to high ionic strength, which bring unique rheological properties to solutions. This study compares and evaluates the emulsifying properties of oil‐in‐water (30:70 v/v) emulsions stabilized with lupin and soya protein isolates and medium molecular weight xanthan gum. The protein was obtained by an isoelectric precipitation method and the polysaccharide was produced by Xanthomonas campestris ATCC 1395 in batch culture in a laboratory fermenter (LBG medium) without pH control. The addition of xanthan gum in the emulsion formulation enhances emulsion stability through the phenomenon of thermodynamic incompatibility with the legume protein, resulting in an increase of the adsorbed protein at the interface. The emulsion stability is also enhanced by a network structure built by the polysaccharide in the bulk phase. Copyright © 2005 Society of Chemical Industry     

Improvement of emulsifying properties of milk proteins with κ or λ carrageenan: effect of pH and ionic strength

The objective of this work was to determine the effect of λ‐carrageenan or κ‐carrageenan on the emulsion capacity, emulsion work and emulsion stability of milk proteins concentrate (MP) or sodium caseinate (SC) emulsions at different levels of pH and ionic strength. Incorporation of carrageenans to proteins emulsions resulted in an improvement of emulsifying properties at pH 6.0 and low ionic strength (0.2 m NaCl). Although emulsion capacity was high in MP than for SC, irrespectively of carrageenan employed, addition of λ‐carrageenan increased twofold emulsion work values (15 327 Ω s^?1 for MP and 11 455 Ω s^?1 for SC; around 6000 Ω s^?1 in the other treatments). Emulsion stability was high with λ‐carrageenan (9.8 s) than MP‐κ‐carrageenan or MP (7.45 and 7.40 s, respectively). Carrageenan improving of emulsion properties was because of the complex formation with MP, characteristic of this type of food system when pH was above of isoelectric point.     

大豆酸溶蛋白/大豆多糖纳米乳液的制备及表征

纳米乳液具有抗沉降和抗乳析动力学稳定性,是提高脂溶性物质的水溶性和生物利用度的有效手段。本论文探索了大豆酸溶蛋白(acid soluble soy protein,ASSP)/大豆多糖(soy soluble polysaccharides,SSP)纳米乳液的制备工艺,系统分析了p H条件、加油量、压力、质量比、热处理等因素对纳米乳液形成以及稳定性的影响。结果表明:在p H 3.0~4.0范围内,酸溶蛋白与大豆多糖质量比1:4,400 bar的压力下,可以很好地包埋5%~20%的油,此时制备的乳液粒径为269.33±2.26 nm,并且储存60天粒径无显著性变化(P0.05)。p H条件、高压以及热处理对乳液的稳定性具有显著影响(P0.05),ASSP/SSP纳米乳液适合食品工业中的酸性介质、高温以及高盐环境下的应用。通过果胶酶水解大豆多糖,对酸溶蛋白/大豆多糖纳米乳液的形态学进行了研究分析,结果表明酸溶蛋白/大豆多糖纳米乳液的微滴表面被多糖覆盖,大豆多糖能够很好地固定在微滴表面并使得纳米乳液微滴稳定和分散。     

The effect of chitosan on the properties of emulsions stabilized by whey proteins

The influence of the cationic amino polysaccharide chitosan content (0–0.5%) on particle size distribution, creaming stability, apparent viscosity, and microstructure of oil-in-water emulsions (40% of rapeseed oil) containing whey protein isolate (WPI) (4%) at pH 3 was investigated. The emulsifying properties, apparent viscosity and phase separation behaviour of aqueous WPI/chitosan mixture at pH 3 were also studied. The interface tension data showed that WPI/chitosan mixture had a slightly higher emulsifying activity than had whey protein alone. An increase in chitosan content resulted in a decreased average particle size, higher viscosity and increased creaming stability of emulsions. The microstructure analysis indicated that increasing concentration of chitosan resulted in the formation of a flocculated droplet network. This behaviour of acidic model emulsions containing WPI and chitosan was explained by a flocculation phenomenon.     

Interfacial and emulsifying properties of lentil protein isolate

The dynamic interfacial tension (DIFT) at oil–water interface, diffusion coefficients, surface hydrophobicity, zeta potential and emulsifying properties, including emulsion activity index (EAI), emulsion stability index (ESI) and droplet size of lentil protein isolate (LPI), were measured at different pH and LPI concentration, in order to elucidate its emulsifying behaviour. Sodium caseinate (NaCas), whey protein isolate (WPI), bovine serum albumin (BSA) and lysozyme (Lys) were used as benchmark proteins and their emulsifying property was compared with that of LPI. The speed of diffusion-controlled migration of these proteins to the oil/water interface, was in the following order: NaCas > LPI > WPI > BSA > Lys, while their surface hydrophobicity was in the following order: BSA > LPI > NaCas > WPI > Lys. The EAI of emulsions stabilised by the above proteins ranged from 90.3 to 123.3 m²/g and it was 93.3 ± 0.2 m²/g in LPI-stabilised emulsion. However, the stability of LPI-stabilised emulsions was slightly lower compared to that of WPI and NaCas-stabilised emulsions at the same protein concentration at pH 7.0. The ESI of LPI emulsions improved substantially with decrease in droplet size when protein concentration was increased (20–30 mg/ml). Reduction of disulphide bonds enhanced both the EAI and ESI compared to untreated samples. Heat treatment of LPI dispersions resulted in poor emulsion stability due to molecular aggregation. The stability of LPI-stabilised emulsions was found to decrease in the presence of NaCl. This study showed that LPI can be as effective emulsifiers of oil-in-water emulsions as are WPI and NaCas at ?20 mg/ml concentrations both at low and neutral pH. The emulsifying property of LPI can be improved by reducing the intra and inter-disulphide bond by using appropriate reducing agents.     

二十二碳六烯酸微藻油乳状液稳定性的影响因素

以二十二碳六烯酸(docosahexenoic acid,DHA)微藻油微胶囊化过程中形成的乳状液为研究对象,通过测定乳状液稳定性、界面膜强度、界面张力、粒径和Zeta-电位,探究乳化剂、pH值和金属离子对乳状液稳定性的影响.结果表明,司盘80与吐温60复配的乳状液亲水亲油平衡(hydrophile-lipophile...     

Heat stability of oil-in-water emulsions formed with intact or hydrolysed whey proteins: influence of polysaccharides

The heat stability of emulsions (4 wt% corn oil) formed with whey protein isolate (WPI) or extensively hydrolysed whey protein (WPH) products and containing xanthan gum or guar gum was examined after a retort treatment at 121 °C for 16 min. At neutral pH and low ionic strength, emulsions stabilized with both 0.5 and 4 wt% WPI (intact whey protein) were stable against retorting. The amount of β-lactoglobulin (β-lg) at the droplet surface increased during retorting, especially in the emulsion containing 4 wt% protein, whereas the amount of adsorbed α-lactalbumin (α-la) decreased markedly. Addition of xanthan gum or guar gum caused depletion flocculation of the emulsion droplets, but this flocculation did not lead to their aggregation during heating. In contrast, the droplet size of emulsions formed with WPH increased during heat treatment, indicating that coalescence had occurred. The coalescence during heating was enhanced considerably with increasing concentration of polysaccharide in the emulsions, up to 0.12% and 0.2% for xanthan gum and guar gum, respectively; whey peptides in the WPH emulsions formed weaker and looser, mobile interfacial structures than those formed with intact whey proteins. Consequently, the lack of electrostatic and steric repulsion resulted in the coalescence of flocculated droplets during retort treatment. At higher levels of xanthan gum or guar gum addition, the extent of coalescence decreased gradually, apparently because of the high viscosity of the aqueous phase.