魔芋胶-黄原胶复配体系流变学特性及其凝胶形成动力学分析

为探究魔芋胶与黄原胶2 种食品胶复配使用后的协同作用,以魔芋胶和黄原胶为原料,控制总凝胶质量分 数为1%,以魔芋胶与黄原胶质量比分别为2∶8、4∶6、5∶5、6∶4、8∶2进行复配后,考察复配体系的流变学特性并对 其凝胶形成进行动力学分析。结果表明：魔芋胶-黄原胶复配体系具有假塑性,当魔芋胶的添加比例逐渐增大时, 复配体系黏度系数K增大,流体系数n减小,且复配体系的动态黏弹性质也随着魔芋胶与黄原胶的质量比不同而改 变,当魔芋胶与黄原胶质量比为6∶4时,复配体系的K值达到最大、n值最小,具有最强的假塑性及黏弹性。同时, 魔芋胶与黄原胶的不同质量比对凝胶形成速率有较大影响,当质量比小于6∶4时,凝胶形成显示出较慢的速率,且 形成的凝胶强度较弱;当质量比为6∶4时凝胶形成速率加快,SDRa曲线和G’曲线上升明显,形成的凝胶强度增大, 当质量比继续增加时,凝胶形成速率反而降低。采用阿伦尼乌斯方程对凝胶形成过程中的动力学参数进行拟合,决 定系数均在0.98以上,表现出较高的拟合精度;凝胶形成过程中的活化能在魔芋胶与黄原胶质量比为6∶4时有显著 增加（P＜0.05）,高温段与低温段间的活化能也表现出明显差异。     

刺槐豆胶与黄原胶复配体系的流变性

研究刺槐豆胶/黄原胶复配体系的流变性,并采用流变学的Cross模型进行拟合分析。结果表明:刺槐豆胶与黄原胶复配可以产生协同作用,当刺槐豆胶与黄原胶的复配体积比为4∶6时,复配体系的黏度最大,触变测试中形成的滞后环面积最大,并且在黏弹性测试中储能模量G’表现出最大值。因此,刺槐豆胶与黄原胶的最佳复配比例为体积比4∶6。对最佳比例复配体系进行不同温度处理后测试可知,最佳复配体系的最适处理温度为80℃,得到的复配体系黏度最大;复配体系的p H值在6.0~10.0之间时,其黏度变化较小,保持相对稳定。     

猪屎豆胶与黄原胶复配胶的流变性研究

本实验主要通过测定体系黏度研究了猪屎豆胶与黄原胶复配胶的流变学性质。实验结果表明,猪屎豆种子胶与黄原胶有较强烈的协效性,二者的最佳复配比为6：4;复配胶的黏度随浓度的升高而升高,浓度达到0．4％时开始形成凝胶,浓度达到0．8％时形成坚实的凝胶,浓度为0．7％时的溶液黏度为5367mPa·s;混合胶液为“非牛顿流体”,溶液具有“假塑性”;胶液的最佳加热温度为80℃,最佳加热时间为1h;pH5～9、冻融变化、苯甲酸钠、超声波和微波处理对对其黏度影响较小;复配胶具有良好的耐盐稳定性。     

黄原胶对莲藕淀粉糊化性质及流变与质构特性的影响

为探究亲水性胶体对淀粉性质的影响,将不同比例的黄原胶添加到莲藕淀粉中,研究两者复配后莲藕淀粉的糊化、流变、质构特性及微观结构的变化。结果表明：黄原胶提高了淀粉糊终值黏度、糊化峰值时间并降低淀粉的崩解值和回生值,复配体系有更好的热稳定性和抗老化性。添加不同比例的黄原胶使莲藕淀粉糊的剪切应力不同程度降低,稠度系数K增大,流体指数n降低,加入黄原胶后的淀粉糊仍为假塑性流体,但是具有更好的增稠作用;加入黄原胶提高了淀粉的贮能模量、损耗模量,降低了损耗角正切值tanδ,体系的黏弹性和稳定性增强,其中莲藕淀粉与黄原胶配比为8.0∶2.0（g/g）的复配体系增稠效果、黏弹性、稳定性最好。复配体系的硬度、内聚性、黏着性、咀嚼性降低,弹性略有增大,添加黄原胶形成的凝胶质地更柔软。扫描电子显微镜观察到添加黄原胶后淀粉内部形成更加均匀稳定的结构。     

玉米淀粉与黄原胶复配体系糊化及回生特性的研究

本文研究了玉米淀粉与黄原胶复配体系的糊化和回生特性。RVA糊化实验表明黄原胶降低了玉米淀粉的成糊温度,并随着黄原胶在复配体系中的比例逐渐增加,其复配体系的峰值黏度和终值黏度均显著增加(p<0.05),崩解值和回生值降低(p<0.05)。热稳定性实验表明加入黄原胶后的复配体系在95℃之后的高温下可以较长时间维持体系的黏度,具有良好的热稳定性。凝沉性实验表明黄原胶可以降低玉米淀粉的凝沉作用,当m(玉米淀粉)∶m(黄原胶)为9∶1时复配体系凝沉作用最小,在120h后仍无明显上清液析出。冻融稳定性实验表明黄原胶能抑制复配体系的回生,提高其冻融稳定性。     

菊粉对刺云实胶-黄原胶复配体系质构和流变特性的影响

将以刺云实胶(Tara Gum)-黄原胶(Xanthan Gum)复配体系为研究对象,探究了添加菊粉(0%、5%、10%、15%、20%,w/w)对复配体系质构及流变特性的影响,并利用电镜扫描技术观察复配体系的凝胶结构。结果表明,添加15%菊粉后复配体系凝胶强度、硬度、咀嚼度、弹性、凝胶形成平均速率(SDRa)、储能模量(G')明显增大,菊粉浓度高于15%后,此六特征值被降低。采用阿伦尼乌斯方程对凝胶形成过程中的动力学参数进行拟合,决定系数均在0.90以上,具有较高的拟合度。与对照相比,添加菊粉后,活化能(Ea)明显降低,高温区与低温区表现出明显的差异。电镜扫描结果显示,添加15%的菊粉通过水合作用促进刺云实胶与黄原胶之间形成更细密、平整的网络凝胶结构,改善了复配体系的质构和流变特性。     

槐豆胶与黄原胶复配胶的流变性研究

对槐豆胶、黄原胶及其复配胶的流变性进行了研究。结果表明,槐豆胶和黄原胶有强烈的协效增稠性,槐豆胶与黄原胶复配胶的粘度随着浓度的升高而升高;复配胶为“非牛顿流体”;复配胶溶液的最佳加热温度和加热时间为60℃,加热60min;pH对复配胶的粘度有一定的影响;冻融变化使槐豆胶和黄原胶复配胶的粘度有较大幅度的增加。     

刺云实胶与黄原胶复配体系质构及流变性研究

将总浓度为1%的刺云实胶(TG)与黄原胶(XTG)按照不同的质量比复配,采用质构仪和流变仪对复配体系的凝胶特性和流变学特性进行测定,通过Carreau模型对流动曲线进行拟合分析,并利用电子扫描显微镜分析复配体系网络形成机理。结果表明:在质构分析中TG与XTG质量比为64时有最大的凝胶强度;在流变分析中TG与XTG质量比为64时呈现最大表观黏度并且在频率扫描和温度扫描中表现出最大的储能模量(G′)。因此,TG与XTG的最佳复配比例为质量比64。在pH为5～10时,最佳复配比例体系的黏度保持相对稳定;当添加盐离子(Na+、Ca2+)后,体系黏度降低,Ca2+降低的趋势更为显著。通过电子扫描显微镜(SEM)分析,表明在TG与XTG之间存在明显的协同增效作用,可形成良好的凝胶网络结构。     

降解瓜胶与降解黄原胶的协同凝胶化及其流变性研究

首次用降解瓜胶与降解黄原胶在一定条件下共混,形成凝胶体系。考察了总胶浓度、氯化钾浓度、制备温度、放置时间、苯甲酸钠及降解食品多糖的分子量等因素对共混凝胶体系黏度的影响,并对其流变特性进行研究。结果表明,降解瓜胶与降解黄原胶可以形成凝胶体系,该体系具有显著的黏弹性和触变性。     

魔芋胶、卡拉胶与黄原胶复配胶的特性及在肉丸中的应用

主要研究了魔芋胶、κ-卡拉胶与黄原胶复配胶的凝胶特性及在肉丸中的应用效果。通过实验证明,影响复配胶凝胶强度的因素和最佳条件是:魔芋胶、κ-卡拉胶与黄原胶的最佳配比为1.3∶1∶0.3;复配胶的总胶浓度为0.6%,且总胶浓度越高,凝胶强度越高;钾离子在较大程度上能影响复配胶的凝胶强度,氯化钾的浓度控制在0.12%,浓度过高会影响口感,浓度过低则会影响凝胶强度;磷酸盐的浓度与凝胶强度成反比;氯化钠的浓度在0.9%最效果最佳;热处理是复配胶形成凝胶的必需条件,复配胶液保持在恒温90℃,恒温加热时间为20min。并最终通过工艺优化得出最适肉丸的加工条件,总胶浓度为0.6%、淀粉添加量为10%,肉糜擂溃时间为15min,水浴加热成型温度为50℃,时间为15min,杀菌煮制温度90℃,时间为20min。     

黄原胶和魔芋胶抑制碱诱导鸭蛋清凝胶的高温液化

本研究分别将黄原胶和魔芋胶添加至鸭蛋清中制备碱诱导凝胶,以探究亲水胶体对凝胶高温液化的抑制作用,结果表明:与对照组相比,添加亲水胶后的蛋清凝胶黏度、储能模量和损耗模量增大明显(p<0.05),褐变强度增加了7.99%和33.21%;当黄原胶和魔芋胶的浓度由0.50%增加至1.50%,凝胶硬度值提高49.60%和119.56%,穿刺强度提高20.59%和78.42%,持水性提高1.02%和9.47%,且添加黄原胶的蛋清凝胶硬度、穿刺强度和持水性均显著大于魔芋胶(p<0.05)。两种胶的浓度均为1.00%时,蛋清凝胶的感官评分最高。两种亲水胶的加入会改变蛋白质的二级结构及凝胶内部的分子间作用力:黄原胶量的增加显著降低了离子相互作用(p<0.05),无规则卷曲减少了41.23%,α-螺旋增加了81.29%;魔芋胶量的增加显著降低了疏水相互作用(p<0.05),β-折叠减少了34.97%,无规则卷曲和α-螺旋分别增加了68.97%和70.37%;氢键和二硫键均随两种胶浓度的增加而增强。综上所述,添加黄原胶和魔芋胶均能抑制碱诱导蛋清凝胶在高温处理过程中的液化现象,且加入黄原胶所形成的凝胶质构特性和持水性优于魔芋胶,而魔芋胶对于凝胶褐变强度的影响大于黄原胶。     

EFFECTS OF ADDED WEIGHTING AGENT AND XANTHAN GUM ON STABILITY AND RHEOLOGICAL PROPERTIES OF BEVERAGE CLOUD EMULSIONS FORMULATED USING MODIFIED STARCH

Stability of beverage emulsion is measured by the rate at which the emulsion creams, flocculates or coalesces, and is generally dependent on rheology of water phase, difference in specific gravities of the two phases and droplet size/distribution of the emulsion. The effects of weighting agents (sucrose acetate isobutyrate and brominated vegetable oil) and xanthan gum on modified starch‐based emulsions were evaluated in this study. Emulsion was formed by addition of 9% coconut oil, in the presence or absence of weighting agents, into the water phase containing modified starch at 10, 12 or 14% without or with the addition of 0.3% xanthan gum. Stabilities of emulsions were evaluated both in the concentrated form used for storage and dilute form used in beverages. The addition of xanthan gum into the water phase decreased the flow behavior index (n) from 0.88 down to 0.31 and increased elastic modulus (G′) over 20 times at elevated frequency (ω = 50 rad/s) and elevated the stability of the emulsion. The xanthan gum‐added emulsion had smaller particle size and demonstrated 14 and 5 times slower phase separation compared to the emulsions without or with the addition of weighting agents, respectively. When the elastic modulus was larger than the viscous modulus (G′ > G″), the emulsions demonstrated greater stability. In dilute beverage solutions, creaming was observed in the absence of xanthan gum.     

Gelling property of soy protein–gum mixtures

Gelling properties of soy protein–gum mixtures were determined by small deformation oscillation measurement and the experimental data were analyzed with blending laws of polymers. Gel strength of soy protein–carrageenan mixture was found to follow either upper or lower bounds depending on the concentration of the constituents, suggesting the occurring of phase shift. G′ of soy protein–xanthan mixed gel always followed the upper bound, indicating that soy protein was the continuous phase regardless variations of the gum concentration. Combination of soy protein with propylene glycol alginate (PGA) produced a mixed gel with high gel strength and stayed above the upper bound at all gum concentrations examined. Covalent bonds between PGA and soy protein was suggested to contribute to the rigidity. Storage modulus of the mixture of soy protein–locust bean gum (LBG) was below the lower bound at low gum concentrations due to the limited demixing process of LBG. G′ values of the mixture of soy protein and LBG–xanthan followed the lower bound but approached upper bound on reducing protein concentration, suggesting that the presence of soy protein might inhibit LBG–xanthan mixture from forming continuous networks.     

Rheological Behavior of Soya Oil-Water Emulsions: Dependence upon Oil Concentration

Stress-strain measurements have been performed in the linear region for soya oil-water emulsions stabilized with xanthan gum for various oil concentrations and for xanthan gum solutions for various xanthan gum concentrations. The big increase observed in the shear modulus for the emulsions (as compared to the solutions) is primarily due to the interaction between xanthan gum molecules and emulsion droplets. The results obtained are in broad agreement with the existing theories for concentrated dispersions and tend to show that the interdroplet interaction is similar to that expected for ‘soft’ deformabe spheres. The results for xanthan gum solutions can be explained if the xanthan gum solutions are not true solutions, but some form of dispersions.     

Effect of gums on the multi-scale characteristics and 3D printing performance of potato starch gel

This research investigated the multi-scale characteristics of potato starch gel (PSG) with different addition ratios of xanthan gum (XG) and locust bean gum (LBG). These characteristics are closely related and had significant impacts on 3D printing performance. Both xanthan gum and locust bean gum were able to increase the apparent viscosity, storage modulus (G′) and loss modulus (G″) of the blended gel system to varying degrees. Large amplitude oscillation shear (LAOS) was used to detect slight rheological differences led by microstructure changes. The critical strain values of the blended gel system rose as the addition ratio of locust bean gum increased. At the same time, the elastic and viscous Lissajous curves could characterize the viscoelastic changes under large strains. Fourier transforms infrared spectroscopy (FT-IR) illustrated that locust bean gum could strengthen the hydrogen bonds so that the gel had stronger mechanical properties compared with the addition of xanthan gum. Scanning electron microscopy (SEM) could observe the changes in the microstructure of the blended gel systems with addition of different addition ratios of gums. From the perspectives of 3D printing results and data analysis, the appropriate amount of xanthan gum improved the fineness and fluidity of the gels by virtue of its lubricating and coating characteristics, while the locust bean gum enabled them to have stronger shape retention abilities and better performances of resisting compressed deformation.     

Rheological behavior of binary and ternary mixtures of polysaccharides in aqueous medium

The rheological behavior of mixtures of xanthan with different galactomannans is examined to evaluate the influence of the structure of galactomannan and that of the mixture composition on the physical properties; the larger synergy is observed for locust bean gum in the presence of xanthan. It is also shown that pH has only a slight influence on the rheology down to pH = 3.59; at lower pH, the G′ modulus decreases significantly.Then, the behavior of xanthan–methylcellulose mixtures is studied, paying particular attention to the storage modulus (G′) of the system, often equated to “gel strength”. The modulus values for direct dissolution of the two polysaccharides in 0.1 M NaCl show that xanthan and methylcellulose are incompatible. The rheological behavior observed is in agreement with DSC results which indicate that no specific interaction between the two polymers exists. However, upon increasing temperature, the modulus of methylcellulose increases substantially between 65 and 70 °C because of physical gelation and dominates the rheology of the mixtures. When temperature is decreased to 37 °C, the clear methylcellulose gel formed remains stable, still giving the main contribution to the overall rheology of the system. Finally, ternary systems are studied when xanthan is mixed with galactomannan and methylcellulose. In this case H-bonds involved in galactomannan–xanthan interaction break when temperature increases causing a decrease in rheological moduli which is then compensated by the gelation of methylcellulose giving an original large increase in moduli for the ternary systems. This can be interpreted as the presence of two independent but interpenetrating networks. The role of pH for these ternary systems is interesting: it is still dominated by methylcellulose and nearly independent of acidic pH (down to pH = 1.8).     

添加成分对外裹糊流变性能及外裹糊鱼块油炸过程油脂渗透的影响

将分别添加黄原胶（0.4%）、大豆纤维（2%）、乳清蛋白（4%）的外裹糊制作油炸外裹糊鱼块,通过测定外裹糊的黏性模量（G”）和弹性模量（G’）以及油炸外裹糊鱼块的水分和油脂含量、微观结构、苏丹红染色水平和油脂分布,探讨添加成分对外裹糊流变性能及外裹糊鱼块深度油炸过程油脂渗透的影响。结果显示：4 种外裹糊（包括对照组,即外裹糊中未添加黄原胶、大豆纤维或乳清蛋白）的G”值和G’值随温度升高先减小后增大,最后趋于稳定,黄原胶组外裹糊的G”值和G’值最大。油炸后黄原胶组的外壳结构紧密,鱼块孔隙小且数量少,具有较高的水分含量和较低的油脂含量。苏丹红染色幅度最大的是对照组,油脂已通过外壳渗入鱼块;黄原胶组染色幅度最小,只出现在外壳中。油脂主要分布在外壳孔隙周围,黄原胶组的荧光强度最低,其次是乳清蛋白组和大豆纤维组,对照组的荧光强度最高。研究结果表明外裹糊中分别添加黄原胶、大豆纤维、乳清蛋白明显影响了外裹糊的流变性能,抑制了外裹糊鱼块深度油炸过程的油脂渗透。     

Enzyme-modified guar gum/xanthan gelation: An analysis based on cascade model

The gel properties of a mixture of enzymatically-modified guar gum (EMG) and xanthan (XG) were investigated. The guar gum sample treated with α-galactosidase to remove galactose residues had a mannose/galactose ratio of 3.02, and was capable of forming a synergistic gel with xanthan. The concentration-dependent and temperature-dependent modulus data for the EMG/XG gel were analyzed by the two-component cascade model which assumed a heterotypic association between segments of EMG and XG. The optimal functionalities (number of cross-linking sites per chain), f_EMG and f_XG, were found to be 300 and 30, respectively. The former is equal to the number of segment size with more than six unsubstituted mannose residues in a galactomannan backbone, while the latter corresponds to a cross-link density of one per 37 repeating units in a xanthan molecule. The cascade analysis of the composition dependence of critical gelling concentration was performed by introducing the effect of the homotypic association of XG or EMG, which became significant in the gel point measurement. The enthalpy change per cross-link for the heterotypic association was found to be two times higher than that for the homotypic association.     

SIMULATING VISCOELASTIC PROPERTIES OF SELECTED FOOD GUMS AND GUM MIXTURES USING A FRACTIONAL DERIVATIVE MODEL

A four parameter semi-empirical model has been developed using the fractional derivative (FD) theory, which consists of applying a mathematical operator to a constitutive equation. The Fourier transform approach is used to obtain the analytical function of the derived model. Since a single four parameter model can predict both storage modulus (G') and dynamic viscosity (η'), the developed FD model was appropriate in describing the viscoelastic properties of selected food gum dispersions, food gum mixtures and gellan gel. This fractional derivative model shows good simulation capability for selected food gum dispersions (0.5% xanthan gum, 0.5 and 0.75% locust bean gum, and 0.5, 0.75, and 1.0% guar gum), 0.6% gellan gel, and binary mixtures of carrageenan and guar gum, car-rageenan and xanthan, as well as guar and xanthan gum.