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The oil and water holding capacities, surface activity, and gelling ability of sodium carbonate-soluble pectin (NSP) extracted from the cell wall of bulb and foliage leaves of yellow and red onion (Allium cepa L.) were investigated and compared with those of commercial citrus pectin. Pectin chemical composition and properties its aqueous dispersions (e.g. the viscosity, pH) were studied. Homogalacturonan was the main component of the low-methoxylated pectin, with a small amount of rhamnogalacturonan I (more branched in the bulb pectin). Both the oil (35–41 g/gd.m.) and water (20 g/gd.m) holding capacities of NSP were higher than citrus pectin (1 and 17 g/gd.m, respectively). The surface activity of NSP was comparable (foliage leaves; surface tension (γ) decrease to 62 mN/m) or higher (bulb; γ decrease to 56 mN/m) than commercial pectin. The ability of NSP, especially extracted from the bulb, to form larger structures with increasing viscosity and neutralizing the negative surface charge, was significantly higher than that of citrus pectin. Therefore, NSP of bulb and foliage leaves may be useful as a carrier of oil- or water-soluble substances, a surface active agent, texturizer and gelling agent in the food, pharmaceutical, cosmetic and agricultural branches of industry. [ABSTRACT FROM AUTHOR]

Abstract The oil and water holding capacities, surface activity, and gelling ability of sodium carbonate-soluble pectin (NSP) extracted from the cell wall of bulb and foliage leaves of yellow and red onion (Allium cepa L.) were investigated and compared with those of commercial citrus pectin. Pectin chemical composition and properties its aqueous dispersions (e.g. the viscosity, pH) were studied. Homogalacturonan was the main component of the low-methoxylated pectin, with a small amount of rhamnogalacturonan I (more branched in the bulb pectin). Both the oil (35–41 g/gd.m.) and water (20 g/gd.m) holding capacities of NSP were higher than citrus pectin (1 and 17 g/gd.m, respectively). The surface activity of NSP was comparable (foliage leaves; surface tension (γ) decrease to 62 mN/m) or higher (bulb; γ decrease to 56 mN/m) than commercial pectin. The ability of NSP, especially extracted from the bulb, to form larger structures with increasing viscosity and neutralizing the negative surface charge, was significantly higher than that of citrus pectin. Therefore, NSP of bulb and foliage leaves may be useful as a carrier of oil- or water-soluble substances, a surface active agent, texturizer and gelling agent in the food, pharmaceutical, cosmetic and agricultural branches of industry.

Improving soil physical properties and increasing water retention in the soil are management strategies in soil and water conservation and enhancing crop yield in rainfed lands. This study was conducted to investigate the role of tillage direction and wheat stubble mulch level in improving soil physical properties in rainfed land in Zanjan province. A field experiment was done at two tillage directions: up to the downslope and contour line, and five stubble mulch levels: zero, 25, 50, 75, and 100% of land cover equal to 6 tons per hectare. A total of 30 plots (2 m×5 m) were created. The results indicated that water infiltration and water content were considerably affected by tillage direction, whereas its effect on water holding capacity was not significant. This physical property of the soil was influenced by the inherent properties of the soil, including particle size distribution. The change of up to down tillage direction to the contour line increased soil infiltration to 11% and water content to 6%. The physical soil properties were wholly influenced by mulch consumption. Soil water content increased in mulch treatments along with water holding capacity and infiltration rate. The highest volumetric water content was at 100% mulch level (10.62%) which was 11% more than the control treatment. However, there was no significant difference between 100% and 75% mulch treatment. This revealed that the application of 75% stubble mulch in contouring tillage is a substantial strategy for improving soil physical properties and controlling water loss in rainfed lands of semi-arid regions.

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Improving soil physical properties and increasing water retention in the soil are management strategies in soil and water conservation and enhancing crop yield in rainfed lands. This study was conducted to investigate the role of tillage direction and wheat stubble mulch level in improving soil physical properties in rainfed land in Zanjan province. A field experiment was done at two tillage directions: up to the downslope and contour line, and five stubble mulch levels: zero, 25, 50, 75, and 100% of land cover equal to 6 tons per hectare. A total of 30 plots (2 m×5 m) were created. The results indicated that water infiltration and water content were considerably affected by tillage direction, whereas its effect on water holding capacity was not significant. This physical property of the soil was influenced by the inherent properties of the soil, including particle size distribution. The change of up to down tillage direction to the contour line increased soil infiltration to 11% and water content to 6%. The physical soil properties were wholly influenced by mulch consumption. Soil water content increased in mulch treatments along with water holding capacity and infiltration rate. The highest volumetric water content was at 100% mulch level (10.62%) which was 11% more than the control treatment. However, there was no significant difference between 100% and 75% mulch treatment. This revealed that the application of 75% stubble mulch in contouring tillage is a substantial strategy for improving soil physical properties and controlling water loss in rainfed lands of semi-arid regions. [ABSTRACT FROM AUTHOR]

ABSTRACT: The effects of using different breadcrumbs (3 wheat, 2 gluten-free: pea and rice) to improve yield and modify the texture of a lean poultry product were evaluated. All breadcrumbs significantly reduced cooking loss (P < 0.05), with one of the wheat crumbs showing the best results (35% reduction). Light microscopy revealed that breadcrumbs were well connected to the cooked meat matrix, and fully hydrated, that is, forming well-structured composite gels. The presence of breadcrumbs resulted in lower hardness, chewiness, and gumminess values of 3 of the treatments (compared to the control with no breadcrumbs), while the other 2 did not affect those parameters. Overall, selected breadcrumbs that are commonly used in ground beef products can be employed to improve yield/modify texture in poultry products but have to be selected to address certain needs.

Hyaluronic acid (HA) is now widely known for its ability to bind water and impart texture. The combined effects of HA and kappa-carrageenan (KC) have not yet been investigated, though. In this study, we looked at the synergistic effects of HA and KC (concentrations of 0.1 and 0.25%, and ratios of 85:15, 70:30, and 50:50 for each concentration) on the rheological properties, heat stability, protein phase separation, water-holding capacity, emulsification properties, and foaming properties of skim milk. When HA and KC were combined in various ratios with a skim milk sample, this resulted in lesser protein phase separation and a higher water-holding capacity than when HA and KC were utilized separately. Similarly, for the sample with a 0.1% concentration, the combination of HA + KC blends demonstrated a synergistic impact with greater emulsifying activity and stability. The samples with a concentration of 0.25% did not exhibit this synergistic effect, and the emulsifying activity and stability were mostly due to the HA's higher emulsifying activity and stability at 0.25% concentration. Similarly, for rheological (apparent viscosity, consistency coefficient K, and flow behavior index n) and foaming properties, the synergistic effect of the HA + KC blend was not readily apparent; rather, these values were mostly due to an increase in the amount of KC in the HA + KC blend ratios. When HC-control and KC-control samples were compared to various HA + KC mix ratios, there was no discernible difference in the heat stability. With the added benefits of protein stability (reduced phase separation), increased water-holding capacity, improved emulsification capabilities, and foaming abilities, the combination of HA + KC would be highly helpful in many texture-modifying applications. [ABSTRACT FROM AUTHOR]

Sandy soil has a low ability to absorb and store low water, low nutrient content, and a high water evaporation rate, so it is not suitable to be used as agricultural land. Superabsorbents can be used to overcome these weaknesses. The purpose of this study was to measure the abilities of the superabsorbents, including water holding, swelling, and water retention of sandy soil enriched with superabsorbent, and to analyze the chitosan-graft-poly(acrylic acid) superabsorbent characteristics. The superabsorbent was prepared by mixing a chitosan solution with ammonium persulfate as an initiator and acrylic acid, which had been neutralized with KOH. Then, the mixture was cross-linked with N,N′-methylenebisacrylamide (MBA). The resulting superabsorbent gel was dried in an oven and then crushed for analysis. The results showed that an increase in chitosan concentration increased the gel fraction, swelling, reusability, and water holding. Meanwhile, an increase in chitosan concentration decreased water retention in sandy soils. The swelling kinetics can be predicted using the pseudo-second-order model with high accuracy (R2 value of 0.99). [ABSTRACT FROM AUTHOR]

Extremophilic microorganisms often produce novel bioactive compounds to survive under harsh environmental conditions. Exopolysaccharides (EPSs), a constitutive part of bacterial biofilm, are functional biopolymers that act as a protecting sheath to the extremophilic bacteria and are of high industrial value. In this study, we elucidate a new EPS produced by thermophilic Bacillus haynesii CamB6 from a slightly acidic (pH 5.82) Campanario hot spring (56.4 °C) located in the Central Andean Mountains of Chile. Physicochemical properties of the EPS were characterized by different techniques: Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), 1D and 2D Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). The EPS demonstrated amorphous surface roughness composed of evenly distributed macromolecular lumps. GPC and HPLC analysis showed that the EPS is a low molecular weight heteropolymer composed of mannose (66%), glucose (20%), and galactose (14%). FTIR analysis demonstrated the polysaccharide nature (–OH groups, Acetyl groups, and pyranosic ring structure) and the presence of different glycosidic linkages among sugar residues, which was further confirmed by NMR spectroscopic analyses. Moreover, D-mannose α-(1→2) and α-(1→4) linkages prevail in the CamB6 EPS structure. TGA revealed the high thermal stability (240 °C) of the polysaccharide. The functional properties of the EPS were evaluated for food industry applications, specifically as an antioxidant and for its emulsification, water-holding (WHC), oil-holding (OHC), and flocculation capacities. The results suggest that the study EPS can be a useful additive for the food-processing industry. [ABSTRACT FROM AUTHOR]

Carboxymethyl cellulose-graft-poly(acrylic acidSodium acrylate-acrylamide) SAPs have been prepared by the free-radical grafting solution polymerization of acrylic acid (AA) and acrylamide monomers (AM) onto carboxymethyl cellulose (CMC) in the presence of N,N′-methylenebisacrylamide as a crosslinker (MBA) and ammonium persulfate (APS) as an initiator. Various factors influencing the water absorbency of the polymer were studied. These include the weight ratio of APS, MBA, and CMC compared to the monomers. The optimal conditions were found as follows: 1% APS, 0.25% MBA, and 10% CMC (weight ratio to monomers). The maximum absorbencies for distilled water and 0.9 wt.% NaCl solution were 406 g/g and 69 g/g, respectively. The structure of the synthesized polymer was confirmed by Fourier Transform Infrared spectroscopy (FTIR). Additionally, the water absorption and water retention behavior of the polymer in soil were investigated. The results showed that this polymer could be employed as a suitable moisture-holding additive in soil for cultivation purposes.

Hyaluronic acid (HA) is now widely known for its ability to bind water and impart texture. The combined effects of HA and kappa-carrageenan (KC) have not yet been investigated, though. In this study, we looked at the synergistic effects of HA and KC (concentrations of 0.1 and 0.25%, and ratios of 85:15, 70:30, and 50:50 for each concentration) on the rheological properties, heat stability, protein phase separation, water-holding capacity, emulsification properties, and foaming properties of skim milk. When HA and KC were combined in various ratios with a skim milk sample, this resulted in lesser protein phase separation and a higher water-holding capacity than when HA and KC were utilized separately. Similarly, for the sample with a 0.1% concentration, the combination of HA + KC blends demonstrated a synergistic impact with greater emulsifying activity and stability. The samples with a concentration of 0.25% did not exhibit this synergistic effect, and the emulsifying activity and stability were mostly due to the HA’s higher emulsifying activity and stability at 0.25% concentration. Similarly, for rheological (apparent viscosity, consistency coefficient K, and flow behavior index n) and foaming properties, the synergistic effect of the HA + KC blend was not readily apparent; rather, these values were mostly due to an increase in the amount of KC in the HA + KC blend ratios. When HC-control and KC-control samples were compared to various HA + KC mix ratios, there was no discernible difference in the heat stability. With the added benefits of protein stability (reduced phase separation), increased water-holding capacity, improved emulsification capabilities, and foaming abilities, the combination of HA + KC would be highly helpful in many texture-modifying applications.

Chicken breast meat is traditionally marinated to improve tenderness and juiciness. However, a significant amount of marinade is purged during cooking. It was envisioned that preheating of marinated chicken breast meat would minimize the purge due to presetting the myofibrillar proteins and will give higher cook yield. The preheating was done in a radiofrequency (RF) oven to provide uniform heating within the volume of the product, and to allow extra marinade retention. Two preheating regimens, 20–30°C and 55–60°C were selected. A 3–4% marinade gain was obtained while the meat was preheated in RF with 10% extra marinade but this gain was not significantly different in the four treatments and the control (p > .05). The cooked meat yields were determined as a function of programmed preheating of marinated meat in the RF oven, followed by final cooking of the product in the air impingement oven. The programmed preheated samples at 20–30°C showed higher cook yield (96.11–100.51%) as compared to the control (95.6%). However, all the samples heated at 55–60°C showed higher cook yield (100.57–109.39%). Warner-Bratzler shear tests were performed on cooked samples to determine the quality of RF preheated product, and the quality of the RF-treated product was not much different from that of the product cooked directly in a conventional air oven.

Binding agents have emerged as an important and required class of ingredients to manufacture a wide range of new food products, especially semi-solid or solid vegan meat and dairy analogues. In this review, we give a definition for this class of ingredients, look at what constitutes required functionalities for binders, and highlight what molecular mechanisms are involved to give rise to these functionalities. Furthermore, an overview on food binders, such as animal-derived/plant-based proteins (myofibrillar proteins, egg white protein, gluten etc.) and carbohydrate-based (methylcellulose, carrageenans etc.) is given and their functions are explained. Three functions have been identified as critically important: stickiness, hardening and water binding. Analytical methods to determine these characteristics are presented and it is recommended to study those simultaneously in model systems, where methylcellulose or gluten might serve as benchmark. [Display omitted] • Characteristics of binders in complex meat and dairy analogues have been defined. • Mechanisms of binder functionalities are explained. • Analytical methods to determine binder characteristics are outlined. [ABSTRACT FROM AUTHOR]

Background: The wetting and hydration stage is the key step in manufacture process of several cereal‐based products. Knowledge of hydration properties of gluten‐free ingredients can contribute to improve the quality of gluten‐free products. The objective of the present work was to investigate hydration properties for a large variety of gluten‐free ingredients. Powders of tow gluten‐free cereals (rice and maize) and powders of tow legumes (chickpea and faba bean) in comparison with durum wheat semolina. The hydration properties were evaluated at 25°C by vapor and liquid water addition. Results: Legume powders had the highest sorption capacity and stronger interaction with vapor water. Rice showed the highest vapor water diffusion at all RH intervals. Water holding capacity, swelling kinetics, and immersion enthalpy in liquid water were higher for legume and maize powders. Conclusion: Gluten‐free cereal powders show hydration properties different from those of legumes. Different combinations of these gluten‐free materials can be made to approach the properties of wheat powders. [ABSTRACT FROM AUTHOR]

Introduction. The used of high pressure and soy protein isolate combinations to emulsion meat products could improve the quality, water holding capacity, texture and increase product yield. Materials and methods. Raw pork batters were prepared as follows: 400g pork meat, 80g pork back-fat, 70g ice water,10g NaCl; sample C2 had 10g soy protein isolate (2%); sample C3 -20g soy protein isolate (4%). The vacuum packed batters were put into a high pressure vessel and were done with 200 MPa for 10 min at 10±2° C. The texture profile analysis of cooked pork batters were carried out using a texture analyzer. Low field NMR relaxation measurements were carried out according in the NMR probe of a Niumag Pulsed NMR analyzer. Results and discussion. Compared with the C1, all the cooking yield of pork batters with various amount of soy protein isolate were increased significantly. The emulsifying activity of 11S globulins was much significantly improved at 200 MPa, that enhanced the water holding capacity of soy protein isolate. High pressure processing induced texture modifications have been used to affect myofibrillar proteins and their gel-forming properties, raising the possibility of the development of processed comminuted meat products. Over 200 MPa treatment, the protein extractability was decreased significantly in meat batters, and caused protein denaturation and/or aggregation, which limited their functionalities. The effects of relaxation time and peak ration of cooked pork batters by high pressure processing with different soy protein isolate were determined. There was three characteristic peaks in the cooked pork batters, which was named as T2b, T21 and T22, respectively. T2b is assigned to water tightly associated to protein and macro-molecular constituents, the relaxation population centered at approximately 0-10 ms in the cooked pork batters. The relaxation population of T21 is centered at approximately 10–100 ms, which is a major component and considered to intra-myofibrillar water and water within the protein structure. Conclusion. The result of low field NMR exhibited that the batters with soy protein isolate had less water out the cooked pork batter and free water. Overall, the 2% soy protein isolate addition could improve the water holding capacity and texture of pork batters treated by high pressure. [ABSTRACT FROM AUTHOR]

Abstract Whey proteins (WP) were replaced with rapeseed proteins (RP) at various protein mixing ratios at neutral pH and ionic strength of 150 mM. Protein gels were formed at 95 °C and another temperature of 80 °C, below the denaturation temperature of RP, to understand the importance of whether RP gelled or not for changes in rheological properties in mixed gels. Gels were analyzed for their microstructure, rheological responses (e.g. G') and water holding (maximum amount of exuded water (A max) and ease with which water can be exuded (k)). The rheological responses obtained for mixed gels was compared to the ones of the single systems at the corresponding concentrations to understand the importance of the rheological moduli of the single systems to the modulus of the mixed gel and to enable the quantification of synergistic stiffening (S = G΄ mixture /(G΄ WP + G΄ RP)). For gels formed at 95 °C a broader window for synergistic stiffening was formed compared to gels formed at 80 °C. Synergistic stiffening occurred when gel coarseness decreased and/or when the differences between the moduli of the individual protein gels were minimized. Water holding properties of mixed gels were tailored due to changes in the gel microstructure or due to synergistic stiffening. The behavior of k as a function of protein mixing ratio in mixed gels was similar to the behavior of gel stiffness. The decrease of k correlated well with an increase in gel stiffness. Gel coarseness and gel stiffness were inextricably linked in regards to their importance for changes in A max. Graphical abstract Image Highlights • Mixing selectively WP with RP results to tailored textural properties. • When gel coarseness decreases, synergistic stiffening is pronounced. • Synergy occurs when the rheological moduli of the individual gels are minimized. • Synergistic stiffening modifies water holding properties of mixed gels. [ABSTRACT FROM AUTHOR]

Chicken breast meat is traditionally marinated to improve tenderness and juiciness. However, a significant amount of marinade is purged during cooking. It was envisioned that preheating of marinated chicken breast meat would minimize the purge due to presetting the myofibrillar proteins and will give higher cook yield. The preheating was done in a radiofrequency (RF) oven to provide uniform heating within the volume of the product, and to allow extra marinade retention. Two preheating regimens, 20–30°C and 55–60°C were selected. A 3–4% marinade gain was obtained while the meat was preheated in RF with 10% extra marinade but this gain was not significantly different in the four treatments and the control (p >.05). The cooked meat yields were determined as a function of programmed preheating of marinated meat in the RF oven, followed by final cooking of the product in the air impingement oven. The programmed preheated samples at 20–30°C showed higher cook yield (96.11–100.51%) as compared to the control (95.6%). However, all the samples heated at 55–60°C showed higher cook yield (100.57–109.39%). Warner-Bratzler shear tests were performed on cooked samples to determine the quality of RF preheated product, and the quality of the RF-treated product was not much different from that of the product cooked directly in a conventional air oven. [ABSTRACT FROM AUTHOR]

The effects of using different breadcrumbs (3 wheat, 2 gluten-free: pea and rice) to improve yield and modify the texture of a lean poultry product were evaluated. All breadcrumbs significantly reduced cooking loss (P < 0.05), with one of the wheat crumbs showing the best results (35% reduction). Light microscopy revealed that breadcrumbs were well connected to the cooked meat matrix, and fully hydrated, that is, forming well-structured composite gels. The presence of breadcrumbs resulted in lower hardness, chewiness, and gumminess values of 3 of the treatments (compared to the control with no breadcrumbs), while the other 2 did not affect those parameters. Overall, selected breadcrumbs that are commonly used in ground beef products can be employed to improve yield/modify texture in poultry products but have to be selected to address certain needs., (Crown Copyright © 2023. Published by Elsevier Inc. All rights reserved.)

This study shows that apart from acting as nutritional value improver, yeast β-glucan can be successfully used to reformulate meat products. When added to meat batters, yeast derived ingredients containing β-glucans (GOLDCELL IY B and GOLDCELL BETA GLUCAN) improved the emulsifying capacity (up to 5 increments), the water holding capacity (up to 8 increments) as well as the emulsion stability. A decrease in total fluid release up to 4.30% and 3.99%, respectively with GOLDCELL IY B and GOLDCELL BETA GLUCAN respectively, at 1.5% addition level was observed. A significant decrease in hardness and fracturability values was also observed, while maintaining the structural cohesiveness of the samples, in part due to the increase in humidity content. A maximum level of 3% ingredient mixture can be added to meat batter formulations without significant impact on sensory characteristics. Adding yeast β-glucan to meat batters can allow food to decrease the NaCl and polyphosphate content in meat products. [ABSTRACT FROM AUTHOR]

The objective of this study was to separate the chitosan (deacetylated products) in the peel and the flesh of loofah ( Luffa aegyptiaca) and cucumber ( Cucumis sativus) to evaluate its water holding capacity, antibacterial and antimutagenicity activities. The levels of glucosamine (degree of deacetylation; DD) in ultrapure deacetylated (UD) chitosan product of loofah and cucumber were much higher than other deacetylated chitosan products. Also, UD chitosan products of loofah and cucumber showed better water absorption and moisture holding capacity. All the deacetylated chitosan products effectively suppress the survival of Staphylococcus aureus and Propionibacterium acnes in a dose-depended manner. Furthermore, UD chitosan products of loofah and cucumber effectively reduced the mutagenicity on various strains of Salmonella typhimurium namely TA100 and TA102. Hence, UD chitosan products of loofah and cucumber might be used to improve skin tone as well as prescribed with a standard chemotherapeutic agent as an adjuvant therapy. Practical applications Luffa aegyptiaca Mill (loofah) and Cucumis sativus L. (cucumber) are common summer vegetables in Asia, especially in Taiwan, India, and China. Recently, the chitosan (deacetylated chitin) present in the fresh loofah ( Luffa) and cucumber attracted more researchers owing to its high biodegradability, nontoxicity, and several other biological properties like antiobesity, antioxidant, and antimicrobial activities. Also, this study shows that loofah and cucumber (UD fraction) are the richest sources for chitosan a vegan source with dermal protective, antibacterial, and antimutagenicity activities. Hence, UD chitosan products of loofah and cucumber may be recommended with other skin protective agents and cancer condition with the standard drug, since it acts as an antimutagenic agent. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of tapioca and potato starch added at 3, 6 or 9%w/w on the physical properties of Spanish mackerel (Scomberomoru guttatus) fish balls. Water holding capacity, gel strength and four attributes of texture profile analysis, namely hardness, springiness, cohesiveness and chewiness increased with increasing starch concentration for both fish balls added with tapioca or potato starch after 6th freeze-thaw cycles. Both tapioca or potato starch-added samples showed decrease in drip loss and colour with increasing starch concentration up to 9% (w/w) after 6th freeze-thaw cycles. Drip loss and colour of fish balls made from the two types of starch decreased with increasing starch concentration. Overall, gel strength, drip loss, and color of fish balls added with starch showed no significant changes (p≥0.05) after 6th freeze-thaw cycle. The results suggested that starch plays an important role in improving freeze-thaw stability of fish balls. [ABSTRACT FROM AUTHOR]

To design food products based on mixtures of proteins from animal and plant sources, understanding of how the structural and mechanical properties of mixed protein systems can benefit from selectively mixing is essential. Heat-induced gels were prepared from mixtures of whey proteins (WP) and soy proteins (SP) at different ratios and constant total protein concentration (10 w/w %). The effect of mixing on the aggregation phenomena (light scattering), mechanical response, and microstructure (CLSM, SEM) was investigated at ionic strengths of 0.1 and 0.3 M. Having similar gelation mechanisms, whey and soy proteins formed one network with both proteins contributing to the gel properties. With an increasing fraction of SP in the mixed protein gel, gel strength and stiffness decreased and water holding increased. In addition, a decrease in gel coarseness was observed, which was most significant for 0–3 w/w % SP fraction. A similar transition was also observed in the aggregation kinetics and aggregate size in dilute solutions. [ABSTRACT FROM AUTHOR]

The sensory perception of foods is directly related to gel morphology. The aim of this research was to investigate the relationship between gel water holding and stiffness for gels with a different morphology. Whey protein gels were prepared by varying ionic strength to create fine and coarse-stranded gels. These gels were characterized for their coarseness, stiffness and their water holding capacity. Fine gels were referred to typical coarseness length scale smaller than 0.1 μm and coarse gels were referred to coarseness length scale larger than 0.1 μm. Water holding was measured both as a function of time and of applied pressure. Increased gel coarseness length scale in both fine and coarse gels resulted in a larger extent of network deformation at a certain applied force. For fine gels, the coarseness length scale of the gel was shown to determine water removal. In the case of coarse gels, coarseness length scale and stiffness had a counteracting effect, but coarseness length scale was still dominant. These results show that the tuning of coarseness length scale of protein networks independent of stiffness or, the other way round, provides a tool to set the water holding capacity in food gels. [ABSTRACT FROM AUTHOR]

To understand the origin of water holding of mixed protein gels, a study was performed on water exudation from mixed whey protein (WP)-gelatin gels upon applied pressure. Mixed gels were prepared with varying WP and gelatin concentration and gelatin type to obtain gels with a wide range of gel properties. Gels were characterized for their water holding (maximum of exuded water, A max , and ease with which water can be exuded, k ), gel coarseness (from CLSM image analysis) and gel stiffness (Young's modulus) at 20 and 40 °C, below and above the melting temperature of gelatin. Gelatin caused an increase in gel coarseness of the WP network, as induced by phase separation between WP and gelatin. The effect of gel coarseness and gel stiffness on A max was found to be intertwined but above all, dictated by the gelatin concentration and gelatin network. At 20 °C, a transition point in gelatin concentration was observed above which stiffness surpassed coarseness in importance for A max . Above this concentration, gelatin dominates the mechanical response of the mixed system. At 40 °C, when gelatin is melted, coarser and less stiff networks, as set by the WP network, lead to higher A max . Tailoring of the coarseness and stiffness and therefore A max and k , can be achieved by selective mixing in terms of protein concentrations, and type of gelatin. By varying gelatin type from A to B, altered phase behavior leads to gels with higher coarseness and lower stiffness but similar A max . [ABSTRACT FROM AUTHOR]

To evaluate the importance of the water holding capacity for the elastically stored energy of protein gels, a range of gels were created from proteins from different origin (plant: pea and soy proteins, and animal: whey, blood plasma, egg white proteins, and ovalbumin) varying in network morphology set by the protein concentration, pH, ionic strength, or the presence of specific ions. The results showed that the observed positive and linear relation between water holding (WH) and elastically stored energy (RE) is generic for globular protein gels studied. The slopes of this relation are comparable for all globular protein gels (except for soy protein gels) whereas the intercept is close to 0 for most of the systems except for ovalbumin and egg white gels. The slope and intercept obtained allows one to predict the impact of tuning WH, by gel morphology or network stiffness, on the mechanical deformation of the protein-based gel. Addition of charged polysaccharides to a protein system leads to a deviation from the linear relation between WH and RE and this deviation coincides with a change in phase behavior. [ABSTRACT FROM AUTHOR]

To increase understanding of water holding in heat-set ovalbumin gels, the relation between aggregate structure (both in solution and in gels) and gel coarseness or gel stiffness is studied. The aggregate morphology obtained by preparation of ovalbumin gels between pH 5.8 and 6.8 differs, as shown by a combination of light scattering, confocal microscopy, electron microscopy and neutron scattering techniques. It is shown that with decreasing pH larger aggregates are formed that are more compact, indicated by the fractal dimension that increased from 1.9 to 2.6. Furthermore, larger, more compact aggregates at pH 5.8 as compared to pH 6.8 resulted in more coarse gels with a less merged microstructures. In addition, a lower gel stiffness is observed at lower pH. The combination of a higher coarseness and lower gel stiffness explains both the lower total water holding and the easier exudation of water from the gel upon applied forces. [ABSTRACT FROM AUTHOR]