Mixture Of Soy Protein Isolate Research Articles

Encapsulation of tomato oleoresin using soy protein isolate-gum aracia conjugates as emulsifier and coating materials

Dry-heated Maillard reaction was applied in the preparation of protein-polysaccharide conjugates. Reaction mixtures containing soy protein isolate (SPI) and gum acacia (GA) were dry-heated at 60 °C and 79% relative humidity for 3, 6 and 9 days. An increase in degree of graft, a* (red) and b* (yellow) parameters was found with increasing reaction time. Structural feature analyses suggested that attachment of polysaccharides to SPI led to changes in spatial structure and unfolding of protein molecules. The conjugates of 6 days showed significantly higher levels of emulsifying properties. Emulsion prepared with SPI-GA conjugates had smaller values of d32 and higher apparent viscosity than those prepared with mixture of SPI and GA. Toxicity assay showed that conjugates exhibited better biocompatibility compared with traditional emulsifier. Furthermore, the conjugates were used as coating material to encapsulate the tomato oleoresin by spray-drying. Moisture content and microencapsulation efficiency of powder increased with an increase in conjugates concentration. The results of controlled release showed that conjugates particles could protect most of the lycopene from being released in the stomach. The lycopene in particles presented an improvement of stability against light, humidity and temperature.

Effect of glycosylation on the mechanical properties of edible soy protein packaging film

In this paper, we explore the glycosylation conditions (glucomannan content, reaction time, temperature and humidity) to probe the relationship between glycosylation and mechanical properties of soy protein isolate (SPI) film. The mechanical properties were characterized by studying the tensile strength (TS) and elongation at break (EB). Furthermore, degree of glycosylation, free glucomannan content, surface hydrophobicity, sulfhydryl groups content, lysine and arginine content of glycosylation soy protein with different reaction time were investigated to certify the significant effect of glycosylation on mechanical properties of soy protein film. What is more, the comparison of TS and EB, contact angle values and water vapor permeability of glycosylation SPI (GSPI), SPI and mixture of SPI and glucomannan films showed the excellence of GSPI. At the end, the analysis of scanning electron microscope was applied to reveal the effect of glycosylation on the structure of films. These results suggested that glycosylation with glucomannan is an ideal method to enhance the mechanical properties of soy protein isolate film.

Resistant starch III from culled banana and its functional properties in fish oil emulsion

Resistant starch from culled banana was produced by lintnerization (acid hydrolysis) and lintnerization prior to autoclaving of obtained starch. The functional properties and bioactivity were evaluated. Oxidative stability and sensory properties of fish oil emulsions produced with soy protein isolate (SPI) and mixtures of SPI with culled banana resistant starch (CBRS) or Hylon VII were evaluated. There was no significant difference (p < 0.05) in resistant and non resistant starch contents among native and different concentration of Lintnerized culled banana starch (CBS). Amylose content was decreased after lintnerization but increased in lintnerized-autoclaved CBS. Fourier transform infrared analysis revealed the modified structures and bonding of the starch materials with the shifting of CO stretch. Rapid visco-analyser (RVA) viscosity values had reduced significantly with increasing the concentration of acid level. Maximum peak viscosity, trough, final viscosity, setback viscosity and peak time were found in native- autoclaved CBS. Swelling power had reduced by lintnerization and further reduced during lintnerization followed by autoclaving. Solubility had augmented drastically in lintnerized CBS ranging from 46.62 to 72.05% but only slight reduction in lintnerized-autoclaved starch than their only lintnerized counterparts. Emulsion made by the mixture of SPI, CBRS and 5% fish oil was the most stable among all emulsions as it produced lowest amount of peroxide value and anisidine value and scored minimum fishy odour intensity initially and throughout the storage period.

Comparative studies on the physicochemical properties of soy protein isolate-maltodextrin and soy protein isolate-gum acacia conjugate prepared through Maillard reaction

Dry-heated Maillard reaction was applied in the preparation of protein–polysaccharide conjugates. Reaction mixtures containing soy protein isolate (SPI) and maltodextrin (1:1 weight ratio) were dry-heated at 60°C and 79% relative humidity for three days. The mixtures of SPI and gum acacia (GA) were dry-heated at the same condition for one week. The conjugate of SPI–MD showed lower levels of free amino groups and higher degree of graft, which indicated that reaction between SPI and MD developed much faster than reaction between SPI and GA. The solubility of SPI at isoelectric point was improved remarkably after grafting with MD or GA. The grafted SPI showed significantly higher levels of emulsifying properties than SPI and the emulsifying properties of SPI–GA conjugate were much better than SPI–MD. Decreases of lysine and arginine contents after the graft reaction indicated that these two amino acid residues attended the covalent linkage between SPI and MD or GA. The graft reaction reduced surface hydrophobicity and fluorescence emission maximum value because of a shielding effect of the polysaccharide chain bound to proteins. The results of secondary structure suggested that grafted SPI had decreased the levels of α-helix, β-sheet and β-turn and increased unordered coils level.

Antioxidant Activity and Emulsion-Stabilizing Effect of Pectic Enzyme Treated Pectin in Soy Protein Isolate-Stabilized Oil/Water Emulsion

The antioxidant activity of pectic enzyme treated pectin (PET-pectin) prepared from citrus pectin by enzymatic hydrolysis and its potential use as a stabilizer and an antioxidant for soy protein isolate (SPI)-stabilized oil in water (O/W) emulsion were investigated. Trolox equivalent antioxidant capacity (TEAC) was found to be positively associated with molecular weight (M(w)) of PET-pectin and negatively associated with degree of esterification (DE) of PET-pectin. PET-pectin (1 kDa and 11.6% DE) prepared from citrus pectin after 24 h of hydrolysis by commercial pectic enzyme produced by Aspergillus niger expressed higher α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, TEAC, and reducing power than untreated citrus pectin (353 kDa and 60% DE). The addition of PET-pectin could increase both emulsifying activity (EA) and emulsion stability (ES) of SPI-stabilized O/W emulsion. When the SPI-stabilized lipid droplet was coated with the mixture of PET-pectin and pectin, the EA and ES of the emulsion were improved more than they were when the lipid droplet was coated with either pectin or PET-pectin alone. The amount of secondary oxidation products (thiobarbituric acid reactive substances) produced in the emulsion prepared with the mixture of SPI and PET-pectin was less than the amount produced in the emulsion prepared with either SPI or SPI/pectin. These results suggest that PET-pectin has an emulsion-stabilizing effect and lipid oxidation inhibition ability on SPI-stabilized emulsion. Therefore, PET-pectin can be used as a stabilizer as well as an antioxidant in plant origin in SPI-stabilized O/W emulsion and thus prolong the shelf life of food emulsion.

A Statistical Experimental Design to Plastein Synthesis with the Mixture of Soy Protein Isolate(SPI) Hydrolysate and Whey Protein Isolate(WPI) Hydrolysate

A statistical experimental design to plastein synthesis which was catalyzed by transglutaminase, using the mixture of soy protein isolate(SPI) hydrolysate and whey protein isolate (WPI) hydrolysate, was investigated. Enzyme/Substrate(E/S:5-25U/g), pH(5-9) and temperature (35-65°C) were selected as major operating variables. To investigate the effects of variables to yield of plastein, the statistical experiment of Box-Behnken design(BBD) and Response Surface methodology(RSM) was employed. Regression analysis showed that the experiment data accorded with the predicted values obtained from quadratic regression equation in BBD with R-Squared of 0.9866 and F-value of 102.51. The optimum results estimated by BBD were as follows: E/S(19.5U/g), pH(6.8), and temperature(50.0°C), gave a maximum plastein yield of 54%. In the present experiment, the preliminary study on plastein functions such as foaming, emulsifying, were showed that plastein had a good biological function.

Influence of soy protein on rheological properties and water retention capacity of wheat gluten

A better understanding of the physicochemical and rheological changes in soy/wheat composite dough may lead to overcome the problems caused by the incorporation of high levels of soy products on bread formulation. The effects of commercial soy protein isolate (SPI) on uniaxial extension and creep behavior, microstructure and free water of hydrated gluten were studied. Different solid:moisture ratios were used. Results showed that the substitution of wheat protein by soy protein negatively affected the gluten–SPI mixture rheological properties due to network weakening. It was demonstrated that gluten was weakened as a consequence of the interference effect of soy proteins on their structure, and the smaller availability of water to the build-up of the gluten network. A greater amount of moisture could partially improve the rheological performance of the gluten–SPI mixture.

Changes in aroma characteristics of simulated beef flavour by soy protein isolate assessed by descriptive sensory analysis and gas chromatography

Descriptive sensory analysis (DA) and gas chromatography (GC) analysis were conducted to investigate changes in aroma characteristics of simulated beef flavour (SBF) upon addition of soy protein isolate (SPI). Five attributes (beefy, roasted, yeasty, soymilk-like and cereal) were selected to assess various mixtures of SBF and SPI. The results of DA confirmed that “roasted”, “beefy” and “yeasty” notes were highly positively correlated with SBF concentration, and the beefy related notes were substantially suppressed by increasing SPI content. Fifteen peaks from GC analysis were selected as indicator peaks to represent beefy attribute based on their odour-active properties assessed by GC–olfactometry and correlation of their peak areas with beefy intensity in mixtures of SPI and SBF assessed by DA. The indicator peaks may form the basis of further research to explicate the nature of SPI–SBF interactions to explain the suppression of perceived intensity of beef flavour in soy protein products.

Effect of the addition of CMC on the aggregation behaviour of proteins

The effect of carboxymethylcellulose (CMC) on the aggregation of formulation based on calcium caseinate, commercial whey protein (WPC), and a 1:1 mixture of soy protein isolate (SPI) and whey protein isolate (WPI) was investigated. Protein aggregation could be observed upon addition of CMC, as demonstrated by size-exclusion chromatography. This aggregation behaviour was enhanced by means of physical treatments, such as heating at 90°C for 30 min or gamma-irradiation at 32 kGy. A synergy resulted from the combination of CMC to gamma-irradiation in Caseinate/CMC and SPI/WPI/CMC formulations. Furthermore, CMC prevented precipitation in irradiated protein solutions for a period of more than 3 months at 4°C.

Effects of the molecular weight on the properties of thermoplastics prepared from soy protein isolate

AbstractCommercial soy protein isolate (SPI) was fractionated into four fractions by an acidifying method from pH 5.7 to 4.5 with 2M HCl. A mixture of SPI with glycerin (50 g/100 g of dry SPI) was compression‐molded to obtain thermoplastic sheets. The weight‐average molecular weight (Mw) of the fractions, the structure, and the mechanical properties of the thermoplastic SPI sheets were investigated with light scattering, IR spectroscopy, wide X‐ray diffraction patterns, differential scanning calorimetry, ultraviolet spectroscopy, scanning electron microscopy, and tensile testing. After heating compression, the SPI sheets were transparent and exhibited a smooth and homogeneous structure. Moreover, the crystallinity degree of the thermoplastic SPI was obviously higher than that of the premix before compression because of the formation of intermolecular hydrogen bonding. The Mw's of the fractions were 1.17 × 105 to 3.21 × 105, and they increased with increasing pH value in fractionation. The mechanical properties and water resistance (R) of the SPI sheets increased with increasing Mw of the SPI fractions. The tensile strength and breaking elongation of the SPI sheets with an Mw value of 3.21 ×105 were 5.7 MPa and 135%, respectively, and the R value was 0.54 after immersion in water for 15 days. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 82: 3373–3380, 2001

Comparison of the effect of soy protein isolate concentration on emulsion stability in the absence or presence of monoglyceride

The stability of oil-in-water (o/w) emulsions was investigated as a function of soy protein isolate (SPI) concentration in the absence or presence of monoglyceride. Emulsion stability (ES) was enhanced with increasing SPI concentration in the absence of monoglyceride. In the presence of 0.5% (w/v) of monoglyceride, however, the maximum ES was obtained at 0.2% (w/v) of SPI concentration, above which significant reduction in ES was observed. The optimum HLB (hydrophile—lipophile balance) concept was suggested to account for the stability of o/w emulsions prepared with mixtures of SPI and monoglyceride as emulsifiers.

Phytate‐calcium interactions with soy protein

AbstractSolubilities of mixtures of soy protein isolate, calcium and phytate were determined as a function of pH and molar ratio of the components. Below the isoelectric point, phytate and protein solubility profiles paralleled each other, indicating some type of protein‐phytate interaction. Addition of phytate shifted the isoelectric point and the minimum solubility to lower values. Between the isoelectric point and pH 6.5, the complex apparently dissociates; addition of phytate results in an increase in the maximum solubility of the phosphorus and the protein, as well as a shift in their solubility profiles. Calcium has no apparent effect on protein solubility in this pH region. Higher pH (&gt;6.5) results in the formation of ternary protein‐calcium‐phytate complexes and a significant drop in calcium and phosphorus solubility, probably due to formation of insoluble calcium phytate salts.

KINETICS OF AVAILABLE LYSINE LOSS DURING THERMAL PROCESSING OF A SOY PROTEIN ISOLATE: REVERSION OF NO-LOSS TO RAPID-LOSS PHASE

Available lysine loss in soy protein isolates may change from a first-order loss to a no-loss phase depending upon processing conditions. The change in reaction kinetics occurs during thermal processing in the absence of shear and pressure. Soy isolate systems do not always exhibit the no-loss phase during extrusion. Thermal processing, a mixture of soy protein isolate and cellulose does not induce the no-loss phase. Once a protein, cellulose and glucose model food system has entered the no-loss phase, pressure in excess of 500 psi (3450 kPa) and shear rates greater than 1000 sec-1 will not revert the no-loss phase to the rapid-loss phase.