Hydrocolloid Concentration Research Articles

Effect of the substrate's microstructure on the growth of Listeria monocytogenes

The effect of the microstructure of the medium on the growth of the food-borne pathogen Listeria monocytogenes was studied. The pathogen's growth kinetics was evaluated using liquid substrates and gels formed from different concentrations of sodium alginate (3.0% w/w) and gelatin (0–30.0% w/w). These results were further verified using a model dairy product with solid concentrations varying from 10.0 to 40.0% w/w. The pathogen's growth was faster in the liquid media than in the gels regardless of the gelling agent employed. The substrate's microstructure, apart from altering the growth pattern from planktonic to colonial, resulted in microbial growth suppression; however, each system affected the microorganism's growth in a different way. The suppressing effect of the substrate's microstructure on microbial growth was also dependent on temperature, while the presence of glucose in the solid medium accelerated microbial growth, thus reducing substantially the difference in growth kinetics between the gels and the liquid media. Any increase in the hydrocolloid concentration, which was also reflected in the rheological properties of the structured samples, resulted in a reduction of growth rate and in an increase of the lag phase of the pathogen. Overall, the gelation of the medium was found to exert a stress on the microorganism since the sol–gel transition, when the pathogen was already at the exponential growth phase, resulted in an additional lag phase or a decrease in the growth rate. The relationship between maximum specific growth rate and loss tangent of the gels (tanδ=G″/G′) was explored, pointing to the possible use of a single structural parameter to describe food matrix effects on microbial growth kinetics.

Feasibility study of Using Liquid Gel in Stabilizing Doogh by Hydrocolloids of Psyllium Husk and Guar Gum

Liquid gel technology is a method that applies in stabilizing of suspension and dispersion of solid particles in beverages. Doogh which is an Iranian traditional and functional drink has allocated a unique position among consumers. Precipitation of hydrocolloids in Doogh has been always one of the most important challenge in producing this drink. Base of this fact, this study deals with using liquid gel technology (Guar gum and Hydrocolloids of Psyllium Husk ) .Different hydrocolloids concentration (0.01, 0.03, 0.05 %w/w) in Doogh heated to be hydrated at 80 ˚C resulting in producing Gel. Their flow behavior, particle distribution and microstructure analyzed, phase separation also evaluated by measuring volume of separated phases .Guar remarkably effected on Doogh flow behavior and caused to a high appare nt viscosity in low shear rates , changing microstructure therefore changing particles size as well. It also subtracted the volume of separated phase .Xanthan and Psyllium increased stability of Doogh by increasing more repulsive force between particles, howeve r larger particles precipitated . Samples containing Guar Gum indicated more yield stress.

Oscillatory and steady shear rheology of gellan/dextran blends.

Oscillatory and steady shear rheology of gellan (G) and dextran (D) solution individually, and in blends (G/D ratio 1:1, 1:2, and 1:3w/v) with a total hydrocolloid concentration of 3% (w/v) were studied at 25°C. Individually, 1.5% dextran and 1.5% gellan in solution exhibited Newtonian and non-Newtonian behavior, respectively. A blend of equal proportion of dextran and gellan (G/D = 1:1) exhibits a distinct gel point (G' = G″), and further addition of dextran in the blend (G/D = 1:2 and 1:3) resulted predominating liquid-like (G″ > G') behavior. A plot of G' vs G″ distinctly showed the gradual transition of the blend. Shear stress (τ)-shear rate ([Formula: see text]) data fitted well the Herschel-Bulkley model. The G/D blend exhibited shear thinning behavior with flow behavior index less than unity. The Cox-Merz rule did not fit well for the complex shear viscosity (η*) and apparent viscosity (η) of the blend.

Development and Optimization of Novel Encapsulation Structures of Interest in Functional Foods Through Electrospraying

The aim of this work was to establish strategies for the development of electrosprayed encapsulation structures, of interest in food applications, based on aqueous hydrocolloid dispersions. Specifically, various polysaccharides and two different proteins were evaluated for capsule formation. To this aim, the hydrocolloid dispersion properties were analysed and compared with the solution properties of two polymers readily spinnable in water (polyvinyl alcohol (PVOH) and polyethylene oxide (PEO)). Increasing the hydrocolloid concentration to promote chain entanglements resulted in a valid strategy only for a few matrices (related to their greater Mw). As alternative strategies to improve the physical properties and, thus, the sprayability of the dispersions, addition of gums and surfactants to modify their viscosity and surface tension, respectively, was evaluated. Moreover, denaturation of proteins was also carried out in order to investigate the effect of this treatment on the electrospraying process and on capsule formation. Results showed that the incorporation of some of these molecules, as well as protein denaturation, significantly changed the physical properties, allowing the development of encapsulation structures from all the hydrocolloids assayed. The morphology of the structures obtained was characterized, and the molecular organization of some of the capsules was studied and related to the electrosprayability and capsules morphology.

Effect of Hydrocolloids and Egg Content on Sensory Quality of Coated Fried Yam Chips

This study investigated the effect of hydrocolloid (xanthan gum, gum tragacanth, and carboxymethyl cellulose) at 0.5–1.5% concentration and egg content (egg white or whole egg) as coating ingredients on the sensory quality of fried yam chips (FYC). The coated chips were evaluated for appearance, texture, taste, flavor, and overall acceptability using a nine-point hedonic scale. Descriptive sensory evaluation of the samples using generic method was also conducted. The studied independent variables had significant (p < 0.05) effects mainly on the appearance and texture of the FYC. Generally, the acceptability scores decreased significantly with increased hydrocolloid concentration (p < 0.05). Appearance had highest significant correlation (p < 0.01, r = 0.764) with overall acceptability. Eight of over fifty descriptors generated by the trained panelists were agreed upon as non-redundant, discriminatory attributes of the coated FYC. Similarity map of the descriptors were defined by two principal components accounting for 53.06% and 40.18% of total variance of rotation sums of squared loadings.

Large amplitudes oscillatory shear (LAOS) behavior of egg white foams with apple pectins and xanthan gum

The study presents the results of research on non-linear rheological properties of foams based on egg white protein, xanthan gum and apple pectin of various levels of methylation. The rheological studies were carried out by means of large amplitude oscillatory shear (LAOS) and Fourier transform rheology (FTR) methods. The obtained foams revealed elastoviscoplastic properties. The analysis of the results allowed determination of yield stress, shear exponents and the Fourier spectra, which enabled estimation of the quantity and intensity of individual harmonics. The Lissajous patterns as well as coefficients of energy dissipation were also demonstrated. The foam containing solely egg white revealed the largest number of harmonics in the Fourier spectrum (17th), whereas supplementation with hydrocolloids induced a decrease in the amount of harmonics (9th). The image of the Fourier spectra was reflected by the Lissajous curves, which gradually acquired an ellipsoidal shape as the hydrocolloid concentration increased. The coefficient of energy dissipation in the function of the deformation amplitude demonstrated a sigmoid dependence and tended towards the value of approximately 0.8 for higher amplitudes. This indicated that the investigated foams were in a flow area. The statistical analysis (two/three-way ANOVA) of the abovementioned values showed that neither the level of methylation nor the pectin concentration in foam influences the yield stress.

Hydrocolloids as a tool for modulating the expected satiety of milk-based snacks

The objective of this study was to discover which rheological profiles are related to greater expected satiety in semi-solid milk-based snacks. Chocolate flavoured snacks were prepared with four different hydrocolloids (alginate, carrageenan, hydroxypropyl methylcellulose -HPMC- and xanthan gum) at three different concentrations. Rheological measurements were carried out in a controlled stress rheometer using a parallel-plates sensor system. Flow curves were obtained at increasing shear rates (0–200 s−1) and viscoelastic properties were measured using small amplitude oscillatory shear tests. The results showed that, in general, increasing the hydrocolloid concentration resulted in greater yield stress, viscosity, thixotropy and viscoelastic moduli, with differences depending on the type of hydrocolloid. For HPMC and alginate, increasing the concentration mainly increased the viscosity, thixotropy and yield stress, while for xanthan gum and carrageenan the most important changes were rises in elastic modulus values and decreased tan δ. The expected satiety delivered by the different samples was evaluated by 50 participants. The snacks were presented physically, sampled and assessed in relation to picture scales of four “comparison foods”: apple, chocolate bar, sandwich (ham and cheese) and doughnut. The results indicated that the effect on expected satiety of increasing the thickness of the snack differed according to the type of thickener used. Expected satiety increased with higher concentration in the alginate and HPMC samples but not in those prepared with carrageenan or xanthan gum. PLS regression showed that viscosity, not solidity (elasticity), determined the expected satiety of semi-solid milk-based snacks.

Mechanism behind the Inhibition of Sweetness Intensity of Aspartame by Guar Gum and Locust Bean Gum

s: Current research on the effects of macromolecular hydrocolloids on sweetness is mainly focused on the properties of hydrocolloids and their texture-taste interactions. In this paper, the influence of two kinds of nonionic food hydrocolloids, Guar gum (GG) and Locust bean gum (LBG) on the taste of aspartame (APM) was studied. Sensory evaluation revealed high concentrations of GG and LBG significantly inhibited the sweetness intensity of APM, especially when their concentrations were higher than C (coil overlap concentration). The mechanism of this phenomenon was investigated using an artificial taste receptor model and isothermal titration calorimetry. The association constant for APM, determined by the artificial taste receptor model, decreased in the presence of GG and LBG. More bound water was found in GG and LBG with an increase in the hydrocolloid concentration, especially at higher than C. Additionally, water diffusion was hampered and this contributed to the lower sweetness intensity. We thus determined the influence of the hydrocolloid on the binding of sweeteners with the receptor, its water mobility as well as its diffusion behavior in the hydrocolloidal texture. The information obtained enables an understanding of the mechanism behind the effects of macromolecular hydrocolloids on taste.

A New Study on the Steady Shear Flow, Thermal and Functional Properties of Beet Pulp Carboxymethyl Cellulose

The current work presents a study of rheological, thermal and functional properties of carboxymethyl cellulose (CMC) produced from beet pulp compared with commercial CMC primarily at low-solid concentrations. Differential scanning calorimetry (DSC) results demonstrated two endothermic peaks around 104, 173C and two exothermic peaks at 307 and 361C. The flow properties of produced CMC were performed under steady shear at different pH and salt (NaCl) contents using Power law equation. Changes in the viscosity were observed depending on the type and concentration of hydrocolloid. Apparent viscosity of CMC samples decreased at acidic and alkaline pH solutions and at the presence of salt, because of the reduction in carboxylate repulsion of the CMC backbone. Furthermore, the effect of produced CMC on rheological and serum loss of ketchup was investigated. The data showed promising outcomes for the addition of beet pulp CMC in ketchup formulation with a decrease in serum separation during storage time. Practical Applications The direct use of food industry wastes in food formulations can help reduce the production costs by decreasing raw material and disposal expenses. The present article demonstrated that the use of beet pulp carboxymethyl cellulose would improve the functional and rheological quality of ketchup products. The outcome of the present study will have greater potential for ketchup industries to develop tomato products.

Effects of endemic hydrocolloids and xanthan gum on foaming properties of white button mushroom puree studied by cluster analysis: A comparative study

White mushrooms are among the most popular edible fungi, and consumption has increased substantially because of their nutritional properties. Fresh mushrooms have a high moisture content and respiration rate and therefore have short shelf life; preservation is therefore necessary. One approach to increasing consumption is to convert mushroom puree into dried powder for use as an ingredient of foods. For instance, mushroom powder could be a functional or nutritional addition to instant soup, noodles, sausage powder, sauces, snacks, extruded baby foods and cereal products. For this purpose, foam mat drying has been introduced.The foaming properties of white button mushroom puree after the addition of the xanthan gum and the endemic seed gums qodume shahri, basil, balangu and cress were investigated. The K-means algorithm was used as a clustering method to select the most suitable hydrocolloid. Foam stability and density increased with increasing concentrations of either xanthan gum or endemic hydrocolloids. In K-means clustering with five clusters, the first cluster of a group of samples with minimum foam density and relatively low drainage volume was selected. Xanthan gum at a concentration of 0.1% (w/w) and cress seed gum at concentrations of 0.3% and 0.5% were selected for preparation of white button mushroom puree foam.

Improving Adhesion of Seasonings to Crackers with Hydrocolloid Solutions

Food powders were applied on crackers that had been coated using water, oil, emulsion, sucrose, or hydrocolloid solutions. The hydrocolloids that were used include gellan gum, kappa-carrageenan, methylcellulose, gum karaya, gum tragacanth, gum arabic, guar gum, modified starch, and maltodextrin. Solutions of similar hydrophobicity to the powder gave the greatest adhesion. NaCl, barbecue (BBQ), ranch, and sour cream & onion (SC&O) seasoning showed greatest adhesion with water, cheese powder with an emulsion of 12.5% to 25% oil, and cocoa powder with oil. For NaCl, BBQ, ranch, and SC&O seasoning, hydrocolloids improved the adhesion over using water alone, with gellan gum providing the greatest adhesion. Hydrocolloid structural differences, including the presence or absence of branching, substitution of sugar units, and molecular weight affect water binding and thickening of the hydrocolloid spray that seemed to be significant factors affecting adhesion of powders to the target surface. For cheese powder, hydrocolloids were capable of replacing the oil within an emulsion while improving or maintaining the same level of adhesion, with gum arabic providing the greatest adhesion. For cocoa powder, hydrocolloid solutions were ineffective adhesives due to differences in hydrophilicity that result in insolubility. The effect of hydrocolloid concentration on adhesion was dependent both on the hydrocolloid type and the concentration that is sprayable, with 0.5% being the optimum concentration for most gums. Adhesion using sucrose solutions was determined by particle size and relative hydrophobicity. Increasing sucrose concentration decreased adhesion of smaller particles, but increased adhesion of larger particles. Adhesion of NaCl significantly increased with decreasing NaCl size using oil, water, and sucrose solutions.

Sinéresis, características reológicas y consistencia sensorial de salsa de alcachofa (Cynara scolymus L.)

The effect of the concentration of three hydrocolloids: CMC, guar gum and xanthan gum on the syneresis, rheological features and sensory consistency of the artichoke sauce (Cynara scolymus L.) Imperial Star variety was studied. The syneresis was determined by the water loss by centrifugation, the rheological features of the artichoke sauce was determined using a Brookfield RVDV – III model rheometer and finally, the sensory consistency was determined by measuring the degree of satisfaction with hedonic scale of nine points. A simplex lattice design blends with centroid expanded under the response surface methodology was applied to establish the effect of the concentration of hydrocolloid on syneresis, rheological features and sensory consistency. In all treatments, the apparent viscosity decreased with shear rate demonstrating a “non Newtonian” behavior of “general plastic” type with an “n” value less than 1 and an initial shear stress. The flow behavior index “n” was in the range of 0.0856 and 0.3131 (n &lt; 1) and the consistency index “k” in the range of 84.55 y 167.80 Pa.sn , the initial shear stress was in the range of 9,10 y 13,51 Pa and consistency sensory presented score of “like” to “like slightly”. Finally, the hydrocolloid mixture was optimized over the area of feasible formulation. With the optimal mixture, corresponding to 0.28% CMC, 0.13% guar gum and 0.59% xanthan gum is expected to obtain a 0.089% of syneresis and a rating of 6 in terms of sensory consistency.

Self-structuring foods based on acid-sensitive low and high acyl mixed gellan systems to impact on satiety

This study investigated the in vitro acid-induced gelation of mixed systems of two biopolymers; low acyl and high acyl gellan gum. Rheological and texture analysis showed that these mixed gels displayed textures that lay between the material properties exhibited for the low and high acyl variants. DSC analysis showed that mixtures of the low acyl and high acyl forms exhibit two separate conformational transitions at temperatures coincident with each of the individual biopolymers.Various metabolically relevant pH environments and hydrocolloid concentrations were investigated. These resulted in very different acid gelled structures, which were characterised by texture analysis. The structures of the acid gels were shown to depend upon the pH, hydrocolloid concentration and proportion of each biopolymer used during their production.A selection of these mixed gellan structures were assessed post-production in terms of their response to prolonged exposure to an acidic (pH 1), stomach-like, environment. This resulted in a significant increase in the gel strength, regardless of the biopolymer proportions. The high acyl gellan was less acid-sensitive, and subsequently no evidence of acid gelation was observed with high acyl gellan at a proportion greater than 60% of the total biopolymer.The findings presented here demonstrate that structuring as well as de-structuring of mixed gellan acid gels can be controlled in acidic environments similar to those that are present in the stomach after food consumption.

Effect of Hydrocolloid Pre-Treatment on Instrumental and Sensory Texture Attributes of Frozen Carrot (Daucus carota)

The effect of different hydrocolloids (pectin, carboxy methylcellulose, xanthan gum, and sodium alginate) pre-treatment used at different concentrations (0.2–0.4%) on instrumental texture parameters as well as on the sensory attributes of frozen-thawed pre-cut carrots was evaluated. Instrumental texture profile analysis of frozen-thawed carrot showed a significant (P < 0.05) increase in cohesiveness with an increase in the concentration of all the hydrocolloids. Nevertheless, the increase in springiness was not significant (P > 0.05) over the untreated control samples, whereas chewiness did not show consistent results with an increase of any of the hydrocolloids. As the concentration of hydrocolloids increased, the firmness values obtained by cutting the frozen-thawed carrot samples with a Warner Bratzler Blade were also found to increase. Higher texture retention after freezing and thawing was observed in xanthan gum (0.4%) pre-treated samples than other hydrocolloids used as well as than the control samples. It increased the firmness up to 196.2% than the control samples. However, 0.3% xanthan pre-treatment gave the best sensory results. Sensory acceptability increased on increasing the pectin and carboxy methylcellulose concentrations, while lower concentration levels of alginate pre-treatment showed higher sensory preference than the higher concentration levels. Based on the results, untreated frozen samples suffered from a detrimental texture and sensory deterioration during 15 months of frozen storage. The carrot tissue integrity was well retained during frozen storage in the hydrocolloid pre-treated samples.

Evaluation of Lepidium sativum seed and guar gum to improve dough rheology and quality parameters in composite rice–wheat bread

The effects of hydrocolloids in rice–wheat flour were studied. Hydrocolloids at 0%, 0.3%, 0.6% and 1% w/w (flour basis) and guar (G), Lepidium sativum seed (L) and guar-L. sativum seed (GL) gum were tested as additives to the rice/flour in various combinations. The quality parameters for the experiment were assessed with farinography, extensography, amylography and texture profile analysis. The evaluation of dough rheology showed that water absorption, dough development time, dough stability and viscosity all increased with the addition of hydrocolloids alone or in a combination. It was demonstrated that G1L1 promoted the highest effect. The mixing tolerance index and gelatinization temperature decreased with an increased hydrocolloid concentration. Extensibility value for the dough that incorporated guar and L. sativum seed gum increased with increasing hydrocolloid concentration from 0.3% to 0.6% and then decreased at 1%. The water activity of all bread didn't have significant differences with increasing hydrocolloids concentration but this parameter 24 decreased during storage. Firmness decreased with increasing hydrocolloid concentration and increased with increasing storage time. The sensory evaluation by a consumer panel gave the higher score for overall acceptability to G0.3L0.3 and G0.3L0.6 samples. The results also showed that G1L1, G1L0.6 and G0.6L1 samples had high specific volume and porosity.

Rheological analysis of emulsion-filled gels based on high acyl gellan gum

Emulsion-filled gels are widely used in cosmetic, food, and pharmaceutical industry. As rheological properties of these systems are strongly dependent on the properties of the gelled polymer network, rheological characteristics of gels containing high and low acyl gellan gum were analyzed. Under the processing conditions low acyl emulsions were unstable, thus in the present work the influence of oil and hydrocolloid concentrations on the viscoelastic behavior of emulsion-filled gels containing high acyl gellan gum was studied. Increasing gellan concentration (from 0.1 g/100 g to 0.5 g/100 g) produced stronger gels, while oil fraction (10 g/100 g–30 g/100 g) slightly affected the elastic behavior of the emulsions reinforcing the structure and the elastic characteristics of the gellan matrix. Sauter diameter (d32) was measured for all emulsions and an average value of 12 μm was obtained. Rheological data (oscillatory and creep–recovery tests) were successfully modeled to interpret the structural characteristics of the gelled emulsions. The broadened Baumgaertel–Schausberger–Winter spectrum was used to represent the linear viscoelastic behavior of the continuous phase and the emulsified system, showing that the rheological behavior of the systems was controlled by the highly structured continuous phase rather than the contribution of filler lipid droplet in the emulsion. Relaxation spectra were validated using creep–recovery experiments. Regardless of hydrocolloid concentration, creep compliance of the gel emulsions decreased compared with their respective gels, showing that the inclusion of oil droplets produced a reinforcement of the structure and the gel strength of the matrix.

Characteristics of gelling agent substituted fruit jam: studies on the textural, optical, physicochemical and sensory properties

SummaryA series of mango jams were prepared using different hydrocolloid solutions (high methoxyl pectin (HMP), carboxymethyl cellulose (CMC), and sago starch) as gelling agents to investigate the effect of hydrocolloid type, hydrocolloid concentration, and freeze‐thaw treatment on the physicochemical, optical, textural, and sensory characteristics. The optical properties results revealed that the total colour change (ΔE) of the sago starch‐based mango jam samples displayed higher values in comparison with samples prepared with HMP and CMC. The textural parameters (hardness, work of shear, stickiness, and work of adhesion) increased with hydrocolloid concentration but decreased with the freeze‐thaw treatment except for sago starch‐based mango jams. The overall acceptability of mango jams containing 6% sago starch was rated similarly to the samples prepared with 0.7% HMP and 0.5% CMC. Principle component analysis revealed that it could be used as an effective tool to segregate characteristics related to fruit jam manufacture.

Physicochemical characterisation of the hydrocolloid from Brea tree (Cercidium praecox)

SummaryThe Brea gum (BG) is a hydrocolloid obtained as phloematic exudate from Cercidium praecox. The exudate was purified by solution and subsequent drying. BG showed high solubility in water 28.3% at 25 °C that increased as temperature was raised. Viscosity of BG solutions increased with BG concentration increase and temperature decrease. Addition of acid or alkali produced changes in solution viscosity as the electrostatic charges on the macromolecule were altered. Solution density at 25 °C increased linearly with hydrocolloid concentration up to saturation. BG lowered the surface tension of water to 51.3 mN m−1 when BG concentration was 5%, remaining constant for higher concentrations. The diameter of oil droplets emulsified decreased and foamability increased with BG concentration increase up to 5% of BG. BG presents adequate functional characteristics for use as stabiliser in preparations with high content of insoluble solids and as stabiliser and emulsifier in emulsions and foams.

A study of diffusion of dyes in model foods using a visual method

Many food processing operations involve mass transfer. The application of electric fields can influence the mass transfer properties of foods. A major limitation of infusion studies is the lack of successful measurement techniques to quantify the depth of penetration and localisation of infused material. Diffusion of two dyes (rhodamine 6G and methylene blue) in agar and alginate gels was visualised insitu for 10min. The experiments were performed at three temperatures (30, 50, and 70°C) and four voltage gradients (167, 333, 500, 667Vm−1) plus a control (0Vm−1). The effect of hydrocolloid concentration and electrical conductivity on diffusion and response to the electric field were tested. The limitations of Fickian analysis led to a new method of data analysis, the penetration model. The effect of the type of gel and the diffusing molecule charge and mass on the combined diffusion and electric field process is discussed.

Influence of Hydrocolloid Concentration, Salinity and Citric Acid Addition on Heat Transfer in the Ohmic Heating Process

In this article, the effects of Ohmic heating process conditions on electrical conductivity and heat transfer were investigated. In order to study the Ohmic heating process, various hydrocolloid solutions containing starch in water with concentrations of 4–8% in the static cells were used. Temperature increments increased electrical conductivity of the solution, linearly. The concentration of dispersed solid particles in the solution caused a progressive trend in time-temperature curve for hydrocolloid solutions (with concentrations of 4, 5.5 and 8%) without electrolytes. The electrical conductivity was raised by increasing temperatures. In order to consider the salinity impact on electrical conductivity and the heating rate, sodium chloride (with concentrations of 1–0.25%) was added to the solution. It was observed that the salt addition to the system had a major effect on electrical conductivity and time-temperature curves. The pH level was modified with Citric acid addition, and the influence of pH level on the time-temperature curves and heating rates were investigated. The Citric acid addition had no on significant effect on the time-temperature curves.