Water Imbibing Capacity Research Articles

Aloe vera Loaded (Polyvinyl Alcohol) Cryogel: Potential Wound Healer

The present work describes the preparation methodology of polyvinyl alcohol and Aloe vera hydrogels and their potential role in wound healing. Aloe vera is frequently used in treating many diseases due to its spectacular properties (anti-inflammatory, antiviral, antitumor and antibacterial) which assist in wound healing and help in treating many diseases a range of ailments. The designing of Aloe vera loaded polyvinyl alcohol (PVA) blend hydrogels (coined as cryogels) was done following repeated freeze-thaw cycles method. Characterization of the cryogels was done using some analytical techniques to study its properties and possible applications. The FTIR spectra shows that Aloe vera loaded PVA cryogels are interconnected by hydrogen bonding. Scanning electron microscope analysis established the porous nature of crogels. These hydrogels show water imbibing capacity, which depends on the experimental conditions and the chemical composition of the gel. The factors affecting the swelling ratio of crogels are amount of PVA, Aloe vera, number of Freez-Thaw cycles, pH and medium. The pore size of the cryogels also decreases with increasing number of freeze-thaw cycles. The Aloe vera-PVA cryogel is healing compatible with blood as there is less than 2% hemolysis.

The Effect of Carboxyl Group Content on Water Uptake Capacity and Tensile Properties of Functionalized Soy Protein-Based Superabsorbent Plastics

This manuscript studies the relation between macroscopic properties of the soy protein isolate (SPI)-based superabsorbent polymers (SAP) (e.g., water uptake capacity and tensile properties) and the extent of chemical modification conducted on the protein. The increase in the carboxyl group content, obtained from electrometric titrations, for acylated systems compared to native SPI brings with it an improvement in the protein hydrophilic character, as revealed by the determination of the water imbibing capacity. SEM images show that larger porous regions were developed in the acylated plastics. As for their mechanical properties, static tensile measurements indicated that acylated plastics with greater water uptake values display higher extensibility, compared to the reference sample. These natural-based SAP materials could be appropriate for applications in which maintaining the dimensional stability during service is not crucial (e.g. in agriculture and horticulture).

Natural superabsorbent plastic materials based on a functionalized soy protein

A natural superabsorbent polymer (SAP) material based on an acylated soy protein was studied as a green alternative to non-biodegradable SAP. In order to obtain the natural SAPs, different amounts of succinic anhydride were used as acylating agent. Once the functionalized protein was obtained, it was mixed thoroughly with glycerol and then molded through a lab-scale injection molding device. Water uptake of samples obtained reached values much higher than those based on unacylated protein. Moreover, a greater extent of the acylation reaction led to higher water uptake values for the corresponding SAPs, probably related to their higher hydrophilic character. Water imbibing capacity measurements and thermogravimetrical analysis (TGA) seemed to confirm this. The presence of larger porous regions in acylated samples observed in SEM images could also play a role in their higher water uptake values.Furthermore, an increase in the extent of acylation reaction led to plastics with lower Young's modulus and higher extensibility.

A natural-based polymeric hydrogel based on functionalized soy protein

Even if most superabsorbent polymers (SAP) used nowadays are synthetic, natural-based SAP hydrogels have been gaining recently special attention due to their biocompatibility and degradability. The present manuscript studies the feasibility of obtaining hydrogels via soy protein functionalization using ethylenediaminetetraacetic dianhydride (EDTAD) as COO− donor. The acylation of the protein was further confirmed by FTIR. Then, TGA tests and mainly the determination of the water imbibing capacity (WIC) of the modified protein samples related a higher extent of acylation reaction to a significant higher increase in the hydrophilic character of the soy protein. Using this functionalized protein as basis and glycerol as plasticizer (50wt.%), bioplastics were obtained through small-scale injection molding. These samples displayed a water uptake capacity up to 2163wt.% higher than that of the corresponding bioplastic based on the unmodified protein used as a reference. This increase in water uptake was observed to be greater as the degree of functionalization was higher. Correspondingly, scanning electron microscopy (SEM) images corroborated that larger porous regions were developed in the acylated bioplastics. On regards to their mechanical properties, an increase in the functionalization degree led to SAP materials with lower Young’s Modulus and higher extensibility than those of the reference sample.These results prove the potential of natural ingredients as proteins in the formulation of hydrogel that might overcome environmental issues related to the non-biodegradability of those based on acrylic derivatives.

Starch–Apple Pomace Mixtures: Pasting Properties and Microstructure

Fil: Rocha Parra, Andres Felipe. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico la Plata. Centro de Investigaciones en Criotecnologia de Alimentos (i); Argentina

Chemical conversion of paper industry effluents into carboxymethylcellulose

The synthesis of carboxymethylcellulose was investigated using effluents containing short cellulose fibers. Carboxymethylcellulose was synthesized according to the slurry process using different amount of sodium hydroxide and different incubation times at 30°C after the etherification reaction as variables. Characterization of the product was conducted by Fourier transformed infrared spectroscopy, X-ray diffraction, degree of substitution, average degree of polymerization, water imbibing capacity, color, rheological properties, apparent viscosity and trace elements content. Incubation time slightly increased the yield of the reaction and the degree of substitution during the first 12h. The reaction yield and degree of substitution both decreased when the initially concentration of NaOH was increased from 7.0g/mL to 10.5g/mL. The carboxymethylcellulose obtained was darker and had lower hydration properties than commercial samples. Trace elements content suggests that the product could be only used in paint factories or building materials industries.

Functional Food Ingredients Based on Sunflower Protein Concentrates Naturally Enriched with Antioxidant Phenolic Compounds

AbstractThe functional properties of three sunflower protein concentrates having different content of phenolic compounds (mainly chlorogenic and caffeic acids) obtained from sunflower oil cake, a by‐product of the oil industry, were evaluated. Sunflower protein concentrates exhibited high water solubility and moderate water‐imbibing and water‐holding capacities. It was possible to obtain foams and emulsions of different stability at different pH and ionic strength from these protein concentrates, as well as self‐supporting gels produced by thermal induction. The presence of phenolic compounds not only conferred antioxidant activity and changed the color of protein products, but also reduced the water imbibing capacity of sunflower protein concentrates, the stability of the emulsions obtained, and the hardness of protein gels. In contrast, phenolic compounds did not modify the water holding capacity, their water solubility or their foaming properties. These results suggest that these protein products may be used as functional ingredients in the food industry.

Effect of polymer solution concentration on the swelling and mechanical properties of glycol chitosan superporous hydrogels

AbstractThis study examined the effect of the polymer solution concentration on the swelling and mechanical properties of glycol chitosan (GCS) superporous hydrogels (SPHs). GCS SPHs were synthesized using a gas blowing method using glyoxal as the crosslinking agent at different polymer solution concentrations. A small change in the GCS solution concentration resulted in a remarkable change in compression strength and swelling kinetics without any significant loss in equilibrium water imbibing capacity. The increase in mechanical strength accompanied by the decrease in swelling kinetics was caused by the generation of smaller pores during the gelation process of the reactant systems associated with a higher polymer solution viscosity. The apparent diffusion coefficients for a variety of GCS/simulated gastric fluid solution systems were determined from the theoretical fitting of experimental dynamic swelling data, explaining the effects of the solution concentration and crosslinking density on the swelling kinetics. The diffusion coefficients determined in this study are expected to be used as the basic information in estimating the swelling kinetics of samples in different dimension. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of Hydrocolloids on Water Absorption of Wheat Flour and Farinograph and Textural Characteristics of Dough

ABSTRACTThe effect of hydrocolloids addition (0, 25, or 1.5 g/100 g of flour) on water absorption of flour and their influence on dough rheology were analyzed. The influence of guar gum (GG), xanthan gum (XG), high‐methoxyl pectin (P), locust bean gum (LBG), and a 1:1 mixture of locust bean gum and xanthan gum (LBG+XG) on water absorption was tested by different techniques including farinograph water absorption, water imbibing capacity, SDS sedimentation test, and sucrose solvent retention capacity. The rheological behavior was analyzed through the farinograph parameters and texture profile analysis (TPA). Principal component analysis (PCA) was applied to evaluate the behavior of the different mixtures. Absorption values obtained by different methods were increased by XG and LBG+XG addition, particularly at the highest levels (1–1.5%). Flour‐P mixtures showed the lowest absorption. GG‐added mixtures led to the more stable doughs and P to the less stable ones. Addition of NaCl increased stability in all cases. According to TPA, softer and less cohesive doughs than control were obtained when hydrocolloids were added, both in conditions of water availability and water restriction (except for XG and GG at the highest levels). However, when enough water was added, more variation in textural attributes among doughs could be observed by PCA. No remarkable differences compared with the control were observed in the gluten network, as evaluated by scanning electron microscopy. Hydrocolloid incorporation led to rheological changes in dough; the trend and degree of this effect was affected by the amount of water added and the structure and concentration of the hydrocolloid.

Study of Some Physicochemical and Functional Properties of Quinoa (Chenopodium Quinoa Willd) Protein Isolates

The amino acid composition and the physicochemical and functional properties of quinoa protein isolates were evaluated. Protein isolates were prepared from quinoa seed by alkaline solubilization (at pH 9, called Q9, and at pH 11, called Q11) followed by isoelectric precipitation and spray drying. Q9 and Q11 had high levels of essential amino acids, with high levels of lysine. Both isolates showed similar patterns in native/SDS-PAGE and SEM. The pH effect on fluorescence measurements showed decreasing fluorescence intensity and a shift in the maximum of emission of both isolates. Q9 showed an endotherm with a denaturation temperature of 98.1 degrees C and a denaturation enthalpy of 12.7 J/g, while Q11 showed no endotherm. The protein solubility of Q11 was lower than that of Q9 at pH above 5.0 but similar at the pH range 3.0-4.0. The water holding capacity (WHC) was similar in both isolates and was not affected by pH. The water imbibing capacity (WIC) was double for Q11 (3.5 mL of water/g isolate). Analysis of DSC, fluorescence, and solubility data suggests that there is apparently denaturation due to pH. Some differences were found that could be attributed to the extreme pH treatments in protein isolates and the nature of quinoa proteins. Q9 and Q11 can be used as a valuable source of nutrition for infants and children. Q9 may be used as an ingredient in nutritive beverages, and Q11 may be used as an ingredient in sauces, sausages, and soups.

Studies on α-amylase induced degradation of binary polymeric blends of crosslinked starch and pectin

A blend matrix of crosslinked starch and pectin was prepared and characterized by infra-red (IR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The prepared blends were investigated kinetically for water sorption studies and alpha-amylase induced degradation adopting a gravimetric procedure. Based on the experimental findings, a plausible mechanism including both diffusion and surface enhanced degradation was suggested and degradation profiles were interpreted. The influence of various factors such as chemical architecture of the blend, pH and temperature of alpha-amylase solution were examined for the swelling and degradation kinetics of crosslinked starch-pectin blends. The effect of concentration of enzyme solution was also studied on the degradation profile of the blends. A correlation was established between the extent of degradation and water imbibing capacity of the degrading blends.

α‐Amylase Induced Enhanced Enzymatic Degradation of Binary Polymeric Blends of Crosslinked Starch and Gelatin

Binary polymeric blends of crosslinked starch (CLS) and gelatin were prepared and characterized by infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The prepared blends were examined for enzymatic degradation taking α‐amylase as a degrading enzyme and the kinetics of degradation process was monitored gravimetrically. A plausible mechanism for α‐amylase induced degradation was suggested and the influence of various factors, such as chemical composition of the blend, pH, and temperature of the enzyme solution and concentration of enzyme solution, were investigated on the degradation profiles of the CLS–gelatin blends. The blends were also studied for water‐uptake potential and effects of various experimental factors such as composition of the blends, pH, and temperature of the swelling bath were investigated on the swelling ratio (SR) of the blends. A correlation was established between the extent of degradation and water imbibing capacity of the degrading blends.

Water uptake by dehydrated soy protein isolates: Comparison of equilibrium vapour sorption and water imbibing methods

Two forms of the hygroscopic behaviour of soybean protein isolates (SPI): liquid water imbibing capacity (WIC) and equilibrium vapour adsorption were tested in non-dialysed native (N) and denatured (D) samples, and in corresponding dialysed isolates (ND and DD). Water activity ( a w) was measured by the optical condensation dew point method. The GAB model adequately predicted the SPI experimental sorption isotherms. The greater number of polar groups exposed during denaturation along with the salt-induced protein aggregation cause the stronger adsorption on D isolate compared with N. No differences between the isotherms up to very high a w were observed between ND and DD isolates. WIC of isolate D was greater than in N and this correlated with higher moisture adsorbed in equilibrium. Denatured non-dialysed isolates may be stored safely at higher moisture contents, and constitute a suitable ingredient for processing nutritionally-enriched formulated foods requiring high water retention.

Hydration Properties of Soybean Protein Isolates

Hydration properties of soybean isolates with different processing conditions (heat treatments, pH and protein concentrations) were studied. Degree of denaturation,, solubility in water, in 0.2mol/L NaCl, and in media of different sodium dodecyl sulfate concentrations, viscosity and water imbibing capacity of the different samples were determinated and correlated. Treatments at temperatures higher than 80ºC denatured 11S and 7S proteins, leading to exposure of hydrophobic groups, which produced insoluble aggregates either in water or in high ionic strength media. These isolates possessed high water imbibing capacities and gave rise to viscous dispersions. Significant correlations were obtained between hydration properties and the "m" coefficient as calculated by a power law equation relating viscosity with the protein concentration of the dispersion. This "m" coefficient also correlated with the denaturation enthalpy of the protein isolates. On the basis of these results, it might be suggested that the "m" coefficient - dependent of the hydrodynamic behaviour of the particles - was a good estimator of the degree of protein denaturation.

Relationships between different hydration properties of commercial and laboratory soybean isolates.

Functional properties related to water protein interactions of soy protein isolates depend on the structural and aggregation characteristics of their major components (storage globulins 7S and 11S) that could be modified by the preparation procedure, thermal and/or chemical treatments, and drying methods. Commercial and laboratory isolates with different functionalities resulting from their structural modifications were compared. Isolates with high solubility or excessive thermally induced insolubilization or compact calcium-induced aggregates caused low water-imbibing capacity (WIC) values. The highest WIC results from the balance between intermediate solubility and the formation of aggregates with good hydration properties. The apparent viscosity of dispersions of commercial (spray dried) and laboratory (lyophilized) isolates depends on the WIC, the morphology and size of the particles, and the interaction of the hydrated particles. The hydration properties and viscosity of protein isolate suspensions were strongly determined by the amount and properties of the insoluble fraction.

Thermal and Electrophoretic Behavior, Hydrophobicity, and Some Functional Properties of Acid-Treated Soy Isolates

In the present work, changes in the structure and functional properties of soy protein isolates caused by mild acid treatment at room temperature were investigated. Different conditions (pH, time, neutralization procedure, and isolate concentration) of acid treatment and consequent salt increase were analyzed. The results obtained show that there is a selective denaturation of 11S protein, which conduces to higher surface hydrophobicity. The solubility of modified isolates decreases with extended storage period of the flour from which they were obtained and with higher isolate concentration during acid treatment. The high water imbibing capacity (WIC) of the resulted insoluble fraction does not produce significant changes in the WIC of the total isolate. The denaturation and dissociation of 11S protein lead to modified isolates with improved capacity to form and to stabilize foams without losing the gel formation capacity. Keywords: Soy protein; soy isolate; chemical modification; acid treatment; thermal ...

Effect of physical and chemical factors on rheological behavior of commercial soy protein isolates: protein concentration, water imbibing capacity, salt addition, and thermal treatment

The influence of different factors on viscosity and rheological behavior of commercial soy isolates was studied. Water imbibing capacity and protein concentration are interdependent parameters which define the viscosity. Groups of isolates determined by differences in the degree of denaturation and aggregation due to processing treatments, as reflected in viscosity and different pseudoplastic behaviors, show significant correlation with those groups based on functional and structural properties or their response to NaCl or NaZS03 addition. The decrease in viscosity due to salt addition is highest in denatured samples with low calcium content. Thermal treatments lead to more viscous dispersions in isolates with partially or even totally denatured proteins. The increase in viscosity is observed even in dispersions with viscosity previously decreased by salt addition.

Water imbibing capacity of soy protein isolates: influence of protein denaturation

Water imbibing capacity of soy protein isolates: influence of protein denaturation

Electrophoretic, solubility and functional properties of commercial soy protein isolates

The aim was to determine the degree of protein denaturation and the relative amounts of the different protein species and to determine the incidence of the structural features of the proteins on the solubility, water-imbibing capacity, viscosity, and gelation capacity of commercial soy protein isolates

The effect of paper industry effluent on growth, pigments, carbohydrates and proteins of rice seedlings

The effect of paper industry effluent on the growth and content of certain macromolecules of seedlings of rice ( Oryza sativa L. cv. Kesari-82K) has been examined. The effects were investigated in relation to both concentration of effluent and time of exposure to the effluent. Percentage of germination, water imbibing capacity, growth, pigment, carbohydrate and protein content showed a decreasing trend with increase in effluent concentration and time. Protein content was the most sensitive macromolecule affected by effluent. Measurement of protein and protein enzymes might therefore provide a useful criterion for the evaluation of the phytotoxicity of effluent released from the pulp and paper industries.