Rheological behaviour of pullulanase-treated guar galactomannan on co-gelation with xanthan

The present study involves the use of non-specific enzyme pullulanase (from Bacillus acidopullulyticus) to remove galactose residues from guar galactomannan to obtain modified guar galactomannan mimicking the functional properties of locust bean gum. The modified guar galactomannan blended with xanthan exhibited the rheological behaviour of elastic modulus (G′) greater than viscous modulus (G″) with a decrease in tan δ value similar to locust bean gum/xanthan blend. Also a twofold increase in the magnitude of elasticity compared to xanthan alone suggested the synergistic interaction with formation of three dimensional networks. The modified guar galactomannan with galactose content of 21% and M:G ratio 1:3.8, almost akin to locust bean gum, showed a better interaction with xanthan. Dynamic stress sweep study of modified guar galactomannan/xanthan blend with increased yield stress of 800 dynes/cm² also indicated the synergistic behaviour. Modified guar galactomannan also revealed the maximum synergistic interaction with xanthan at a mixing temperature of 60 °C than at 20 °C, 30 °C, 40 °C and 50 °C, respectively. Modification of guar galactomannan by pullulanase is an alternative route to produce galactose-depleted guar galactomannan with enhanced rheological functionalities on co-gelation with xanthan, as a cost effective replacement to locust bean gum.     

Synergistic interaction of xanthan gum with glucomannans and galactomannans

Xanthan gum forms thermoreversible gels when mixed with konjac mannan or locust bean gum. The stronger gels are formed with konjac mannan and the maximum gel strength for the mixed systems in the absence of electrolyte occurs at a xanthan-konjac mannan or xanthan-locust bean gum mixing ratio of about 1:1. In the presence of 0.04 mol/dm³ NaCl the optimum mixing ratio is unchanged for xanthan-locust bean gum blends but changes to about 2:1 for xanthan-konjac mannan blends. These observations support differential scanning calorimetric data which are able to monitor both gelation and the conformational transition of the xanthan molecules and indicates that (i) in the absence of electrolyte konjac mannan interacts with disordered xanthan chains whilst in the presence of 0.04 mol/dm³ NaCl it interacts with ordered xanthan chains, and (ii) locust bean gum interacts with ordered xanthan chains both in the presence and absence of electrolyte.     

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。     

Viscosity of solutions of xanthan/locust bean gum mixtures

Xanthan and locust bean gums are polysaccharides able to produce aqueous solutions with high viscosity and non‐Newtonian behaviour. When these solutions are mixed a dramatic increase on viscosity is observed, much greater than the combined viscosity of the separated polysaccharide solutions. In this work the influences of different variables on the viscosity of solutions of mixtures of xanthan/locust bean gum have been studied. Total polysaccharide concentration, xanthan and locust bean ratio on mixture and temperature at which the gum was dissolved (dissolution temperature) for both xanthan and locust bean gums have been considered. Under these different operational mixture conditions shear rate and time have also been considered to describe the rheological behaviour of the solutions studied. The high viscosity increase observed in these mixtures is due to the interaction between xanthan gum and locust bean gum molecules. This interaction takes place between the side chains of xanthan and the backbone of the locust bean gum. Both xanthan molecule conformation in solution – tertiary structure – and locust bean gum structure show great influence on the final viscosity of the solution mixtures. Xanthan conformation changes with temperature, going from ordered structures to disordered or chaotic ones. Locust bean gum composition changes with dissolution temperature, showing a dissolved galactose/mannose ratio reduction when temperature increases, ie the smooth regions – zones without galactose radicals – are predominantly dissolved. The highest viscosity was obtained for the solution mixture with a total polysaccharide concentration of 1.5 kg m⁻³ and a xanthan/locust ratio of 2:4 (w/w) and when xanthan gum and locust bean gum were dissolved at 40°C and 80°C, respectively. © 1999 Society of Chemical Industry     

Small and large deformation viscoelastic behaviour of selected fibre blends with gelling properties

Dietary fibres can be used as valuable functional ingredients in baked goods, as thickeners and gelling agents as a result of their ability to modify the structural properties of the matrix in which they are embedded. Viscoelastic behaviour of 12 selected gel–fibre blends (carboxymethylcellulose, hydroxypropylmethylcellulose, locust bean gum, high ester pectin, fructo-oligosaccharide and gluco-oligosaccharide) prepared at 10% concentration (w/v) was investigated at 25 °C and 95 °C by applying both fundamental and empirical rheological techniques to explore their usefulness/suitability as structural ingredients in diluted and weakened baking systems such as gluten free matrices. Mechanical and thermo-mechanical properties were recorded by using a controlled stress rheometer, measuring the storage modulus (G′), the loss modulus (G″) and the complex viscosity (η*). Textural characteristics were assessed by using a TAXTplus Texture Analyser with different attachments. Penetration and back extrusion tests were used for solid and liquid-like samples, respectively. The overall results indicated that (i) carboxymethylcellulose and pectin formed the strongest and the weakest gels, respectively, and that (ii) temperature had a significant effect on gel strength improvement especially for locust bean gum. A 30% substitution of hydrated fibres (cellulose derivates, galactomanans and high ester pectin) by prebiotics (fructo-oligosaccharides and gluco-oligosaccharides) led to a significant decrease of gel structure rigidity when compared to an identical system without prebiotic addition. Only locust bean gum exhibited an opposite behaviour inducing an increase in values of both dynamic moduli (G′ and G″) and static hardness. Significant relationships between dynamic (rheometry) and static (texture analysis) methods were found. Strengthening and structuring ability of some fibre blend gels endorsed them to be used as promising functional ingredients to make gluten-free bread by using low cost thickeners' agents.     

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.     

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.     

Flow properties of fruit fillings

The flow properties of the fluid portion of fruit fillings were assessed to investigate the effects of gums. Results indicated that the shear rate–shear stress relations of the fluid portion of commercial fruit fillings and the model fillings made of waxy corn starch, fructose, citrate buffer, and a gum which could be guar gum, locust bean gum, CMC, xanthan gum or κ-carrageenan, fit well into the Herschel–Bulkley equation for pseudoplastic fluids. The fluid portion of the commercial fruit fillings was characterized with a yield stress between 39–51 Pa, a consistency index between 52–104 Pa·sⁿ, and a flow index (n) around 0.4. In addition, the shear rate–shear stress relations could be fitted into a modified Herschel–Bulkley equation with a flow index fixed at 0.4. Addition of guar gum, locust bean gum and CMC increased while xanthan gum and κ-carrageenan decreased the consistency and flow indices in the modified Herschel–Bulkley equation. The effect of gum addition on the apparent viscosity of model fillings varies with the type of gum, amount of addition, and shear rate.     

Effect of locust bean/xanthan gum addition and replacement of pork fat with olive oil on the quality characteristics of low-fat frankfurters

The effects of reducing fat level from 20% to 12% and 9%, substituting pork fat with olive oil and adding locust bean/xanthan gum (0.5% and 0.6%) on emulsion stability, jelly and fat separation, processing yield, cook loss, texture and sensory characteristics of frankfurters were investigated and compared with control samples. Addition of locust bean/xanthan gum produced a significant increase in hydration/binding properties, characterised by lower cook losses, increasing yield, better emulsion stability and lower jelly and fat separation. The substitution of pork fat by olive oil did not affect these parameters. Indeed, results showed that reducing fat levels together with increasing moisture and locust bean/xanthan gum addition do not affect the sensory or textural properties, but olive oil addition produces a decrease in hardness and an increase in adhesiveness, however the overall acceptability was not affected.     

Effect of Anionic Gums on the Texture of Pickled Frankfurters

The addition of the anionic gums, xanthan and carrageenan, stabilized the texture of frankfurter emulsions against acid deterioration at 37°C in vinegar pickle. The proteins collagen, casein, and gluten, and the gums guar, arabic, and locust bean had no effect. The cationic gum, chitosan, formed an acid-stable gel but the gel would not hold the emulsion. The process of acid deterioration had an initial period of firming of the gel texture. Shear (rupture) and elasticity did not show a corresponding initial increase. Subsequent deteriorative changes were less in the emulsions with xanthan gum than in any of the other emulsions. The gum gel is formed at the expense of the protein-fat structure, probably through a gum-protein interaction.     

Swallowing profiles of food polysaccharide solutions with different flow behaviors

The relationship between physiological response and sensory perceived scores in swallowing was investigated using food polysaccharide solutions. Solutions from xanthan gum (0.3–0.9%) and locust bean gum (0.5–0.8%) were used as specimen with different flow behaviors identified by static and dynamic rheological methods. Acoustic analysis and sensory evaluation were carried out to investigate the swallowing profiles using the same human subjects. From acoustic analysis, time required for bolus to transfer through the pharyngeal phase t₂ decreased with increasing concentration of xanthan gum despite the viscosity increase. Also, the acoustic balance for the swallowing sound shifted to a higher frequency range with increasing concentration. The t₂ for locust bean gum was much less concentration-dependent and consistently larger than that for xanthan gum when compared at equivalent shear viscosity at 10 s⁻¹. Also, the acoustic balance for the swallowing sound was less concentration-dependent than that for xanthan gum. From sensory evaluation, 0.6% xanthan gum was scored the highest in perceived swallowing ease, while 0.75% locust bean gum was scored the lowest. Both t₂ and the acoustic balance correlated well with perceived swallowing ease. Results indicate that xanthan gum solutions flow as one coherent bolus through the pharyngeal phase with smaller variation of flow velocity than locust bean gum solutions, leading to a greater sensation of swallowing ease. “Structured fluid”, defined as fluid with yield stress such as xanthan gum solutions, is a rheological nature that allows bolus to be swallowed in one go, relating to perceived swallowing ease of liquid foods.     

Study of emulsions stabilized with Phaseolus vulgaris or Phaseolus coccineus with the addition of Arabic gum, locust bean gum and xanthan gum

The properties of o/w emulsions stabilized with 1%w/v common bean (Phaseolus vulgaris L.), V or scarlet runner bean (P. coccineus L.), Coc extracted by isoelectric precipitation or ultrafiltration, at pH 7.0 and 5.5, with the addition of Arabic gum, locust bean gum, xanthan gum and a mixture of xanthan gum–locust bean gum (0.1 %w/v and 0.25 %w/v) are studied. The stability of emulsions was evaluated on the basis of oil droplet size, creaming, viscosity and protein adsorption measurements. The addition of Arabic gum, caused an increase in D[4,3] values and a decrease in the amount of protein adsorbed at the interface. The addition of locust bean gum in some emulsions reduced the amount of protein adsorbed. The addition of xanthan and to a less extend of the polysaccharide mixture, promoted a decrease in D[4,3]. So, emulsion stability was affected by the polysaccharide nature. Differences were also observed with respect to the protein nature, the method of its preparation and emulsion's pH. All polysaccharides enhanced the emulsions viscosity with xanthan and xanthan–locust bean gum exhibiting the higher values. V isolates and isoelectricaly precipitated isolates of both V, Coc showed higher viscosity values. The stability was enhanced by the increase of the viscosity of the continuous phase and the creation of a network, which prevents the oil droplets from coalescence.     

Textural properties of legume protein isolate and polysaccharide gels

The influence of legume proteins from lupin, pea and fababean on the formation of gels prepared by heat treatment in the absence or presence of xanthan gum, locust bean gum and NaCl was investigated. The resulting fracture and texture properties of gels not only are associated with the heating process used to form the gel but also depend on the conformational aspects of xanthan–locust bean gum in admixture with legume proteins, which after 10 days of aging reinforce the system. The fracture and textural properties are explained in terms of the effect of the protein–polysaccharide molecular structure and physicochemical conditions applied in the gel system during the gel preparation and measurements. Copyright © 2006 Society of Chemical Industry     

Functionality of medium molecular weight xanthan gum produced by Xanthomonas Campestris ATCC 1395 in batch culture

Xanthan gum of medium molecular weight was produced by Xanthomonas Campestris ATCC 1395 in a laboratory fermenter without pH control by applying a stirrer speed of 600 rpm and its stabilization properties in salad dressing emulsions were evaluated. The gum performed satisfactorily as an emulsion stabilizer and thickener although it had to be used in higher concentrations in order to be as effective as the commercially available xanthan gum. Furthermore, resilient gel structures resulted when the gum was used in an admixture with locust bean gum. The gel texture profile was different compared to that of the commercial sample/locust bean gum mixture, suggesting that the gum could present an alternative for the preparation of gels of acceptable textural properties.     

Surface tension of Phaseolus vulgaris and coccineus proteins and effect of polysaccharides on their foaming properties

The surface tension of protein isolates from common bean (Phaseolus vulgaris L.) and scarlet runner bean (Phaseolus coccineus L.), prepared by isoelectric precipitation and ultrafiltration was evaluated, with respect to protein concentration (0.001–0.1% w/v) and pH (pH 4.5, 5.5, 7.0 and 8.0). Surface tension was most reduced, and with a higher rate of reduction at higher protein concentration and at pH 8.0. Foams (1, 2% w/v protein), at the same pH values, with and without the addition of polysaccharides, were studied. The proteins’ foaming behaviour was related to their adsorption behaviour. Arabic gum, locust bean gum (0.1% and 0.25% w/v), xanthan gum and a xanthan/locust bean gum mixture (0.1% w/v) had a positive effect on foam creation. All polysaccharides increased foam stability, probably due to the viscosity increase and to the creation of a network, which prevents the air droplets from coalescence. Isolates from P. coccineus and isolates obtained by ultrafiltration seemed to exhibit better foaming properties.     

Rheological interactions between Lallemantia royleana seed extract and selected food hydrocolloids

BACKGROUND: Lallemantia royleana (Balangu) is a mucilaginous endemic plant which is grown in different regions of world. The flow behaviour of Balangu seed extract (BSE) and its mixture with xanthan, guar and locust bean gums at 1:3, 1:1 and 3:1 ratios, in addition to control samples (0% BSE), were evaluated. To describe the rheological properties of samples, the power law model was fitted on apparent viscosity–shear rate data. To evaluate the interaction between BSE and selected hydrocolloids in dilute solutions, the relative viscosity was also investigated. RESULTS: There was no significant difference between the consistency coefficient of guar and locust bean solutions and their blends substituted with 250 g kg^?1 BSE. The BSE–xanthan mixture at 1:3 and 1:1 ratios had consistency index equal to xanthan solution. BSE–locust bean gum at all ratios, BSE–xanthan at 1:3 ratio and BSE–guar gum at 1:1 and 3:1 ratios indicated relative viscosity lower than values calculated assuming no interaction. The intrinsic viscosity value of BSE was determined 3.50 dL g^?1. CONCLUSION: The apparent viscosities of BSE, selected hydrocolloids and their blends were the same at a shear rate of 293 s^?1 and the commercial gums can be substituted by 250 g kg^?1 and 500 g kg^?1 BSE. Copyright © 2011 Society of Chemical Industry     

增稠剂和乳化剂对豆浆稳定性的影响

为增加豆浆的稳定性,采用测定豆浆稳定系数、表面张力及进行感官评分的方法筛选适合用于豆浆样品的增稠剂和乳化剂,确定了最适宜的豆浆增稠剂和乳化剂的种类及其用量。经过黄原胶、刺槐豆胶、卡拉胶、结冷胶和海藻酸钠的单因素实验,黄原胶和刺槐豆胶的复配实验及黄原胶、刺槐豆胶和乳化剂(单硬脂酸甘油酯和蔗糖脂肪酸酯)的正交实验得出以下结果:黄原胶和刺槐豆胶对增加豆浆稳定性有着较好的效果,当它们的质量浓度分别为0.2g/L时,其稳定系数分别为0.737、0.742。单硬脂酸甘油酯和蔗糖脂肪酸酯复配后HLB=8、质量浓度为2g/L时,豆浆样品的稳定性最好,表面张力为41.7mN/m。当黄原胶、刺槐豆胶、乳化剂质量浓度(单硬脂酸甘油酯质量∶蔗糖脂肪酸酯质量=7∶4)分别为0.14、0.14、2g/L时豆浆的稳定性最好,此时豆浆样品的稳定系数为0.879,表面张力为41.6mN/m,感官评分为96。     

Effect of κ-carrageenan on milk protein polysaccharide mixtures

The effect of κ-carrageenan (0, 0.025, 0.05%) on phase separation between polysaccharides (0.36% of locust bean gum (LBG), guar gum, or xanthan gum) and milk proteins (from 10.5% skim milk powder) in solution was studied. Xanthan gum was seen to be the most incompatible with milk proteins, followed by guar gum and LBG. Casein micelles were more incompatible with all polysaccharides than whey proteins. Whereas at either concentration κ-carrageenan inhibited visual phase separation, it was seen by transmission electron microscopy that samples with κ-carrageenan showed microscopic phase separation. Samples with 0.05% κ-carrageenan and either LBG or guar gum and all samples with xanthan gum could be described rheologically as weak gels, while those with no or 0.025% κ-carrageenan and either LBG or guar gum could be described as concentrated solutions. Thus, no correlation was seen between the inhibition of macroscopic phase separation by κ-carrageenan and the formation of a weak gel in solution.     

Optimization of Gum Combination in Prebiotic Instant Hot Chocolate Beverage Model System in Terms of Rheological Aspect: Mixture Design Approach

Mixture design was used to investigate the effects of four different gums (xanthan gum, guar gum, alginate and locust bean gum) and their combinations on the rheological properties of a prebiotic model instant hot chocolate beverage (including 3.5% inulin) and to determine their interactions in the model beverage. Simplex centroid mixture design was applied to predict the physicochemical (soluble solids, pH, colour properties) and rheological parameters (consistency index (K), flow behaviour index (n) and apparent viscosity (η ₅₀)) of the samples. In the model, the optimum gum combination was found by simplex centroid mixture design as 59% xanthan gum and 41% locust bean gum, and the highest K value was 33.56 Pa s ⁿ . The increase of guar gum and alginate in the gum mixture caused a decrease in the K value of the sample.     

Effects of gelatinisation level, gum and transglutaminase on the quality characteristics of rice noodle

The aim of the present study was to investigate the effects of gelatinisation level, gum (locust bean gum, xanthan gum, 3%) and/or transglutaminase (TG, 0.5%) on quality characteristics of rice noodle. In order to improve the dough forming ability, rice flour was gelatinised at levels of 15%, 20%, 25% and 30%. Noodle samples were evaluated in terms of cooking loss, total organic matter (TOM), water absorption, swelling volume, maximum force, colour, sensory properties, pasting properties. Noodle sample with a gelatinisation level of 25% had better cooking and sensory properties. Gum and/or TG were added to this noodle formula. The noodle samples including xanthan gum had better cooking and sensory properties. TG caused a significant decrease in TOM. The samples including locust bean gum had significantly higher maximum force values. Xanthan gum caused decreases in some Rapid ViscoAnalyzer viscosity values of the noodle samples, while locust bean gum caused increases.