• Korean Journal of Food Science and Technology
• /
• v.31 no.6
• /
• pp.1488-1494
• /
• 1999

Effect of ${\gamma}-irradiation$ on the SDS-PAGE pattern, secondary structure content, the solubility of commercial soy protein isolate (SPI) and whey protein concentrate (WPC) was investigated. The change in the subunit molecular weight of SPI and WPC irradiated in aqueous solution or dried state was studied using SDS-PAGE. The SDS-PAGE pattern of SPI irradiated in aqueous solution revealed the fragmentation and aggregation of the subunit protein. For WPC irradiated in aqueous solution. fragmentation of the subunit protein up to 10 kGy was observed. In contrast, ${\gamma}-irradiation$ of SPI and WPC in dried state did not cause any significant changes in the SDS-PAGE pattern. The change In the secondary structure of irradiated SPI and WPC solution was studied using circular dichroism. The aperiodic structure content of SPI and WPC solution increased at higher irradiation doses, which suggests that ${\gamma}-irradiation$ caused the disruption of the ordered structure of SPI and WPC solution. Gamma-irradiation also caused the change in solubility of SPI and WPC in dried state.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.51 no.2
• /
• pp.148-153
• /
• 2006

Effects of ${\alpha}$-chymotrypsin modification on degree of hydrolysis (DH), solubility, emulsifying capacity and thermal aggregation of laboratory-purified soy protein isolate (SPI) using a lipoxygenase-defected soybean (Jinpum-kong) and commercial soy protein isolate (Supro 500E) were compared. SPIs were hydrolyzed by ${\alpha}$-chymotrypsin at pH 7.8 and $37^{\circ}C$ for 30 min. DHs of Supro 500E and Jinpum-kong SPI were increased by ${\alpha}$-chymotrypsin modification, and DH of Supro 500E was higher than that of Jinpum-kong SPI. DH of ${\alpha}$-chymotrypsin treated Jinpum-kong SPI was similar with untreated Supro 500E and DH of treated Supro 500E was the highest. Solubility, emulsifying capacity and thermal aggregation of SPIs were increased by ${\alpha}$-chymotrypsin modification, and these changes were highly related to changes in DH. Functional properties of Supro 500E were higher than Jinpum-kong SPI in both of untreated and ${\alpha}$-chymotrypsin treated SPIs.

• Food Science and Biotechnology
• /
• v.15 no.4
• /
• pp.631-634
• /
• 2006

Soy protein isolate (SPI) films were supplemented with cinnamaldehyde (CA) at concentrations of 0.1-0.5 mL/5 g SPI. The effects of CA on film color, tensile strength (TS), percent elongation at break (E, %) and water vapor permeability (WVP) of SPI films were investigated. Generally, total color difference (${\Delta}E$), WVP, and TS of SPI films increased gradually, while E and TSM decreased significantly (p<0.05) as the amount of cinnamaldehyde in the SPI films increased. Cinnamaldehyde can be used as a potential cross-linking agent for preparing SPI films by improving mechanical strength and water resistant properties.

• Food Science and Preservation
• /
• v.8 no.2
• /
• pp.181-186
• /
• 2001

The objective of this study is to determine the effect of soy protein isolate (SPI) film coating on the color, firmness, viscosity and weight loss of Rice Cake stored at 15, 20 and $25^{\circ}C$ (RH 50%) for 30 days. Raw materials mixed with SPI and cocoa powder (10:0, 7:3, 5:5, 3:7, w/w) were prepared. After adding sugar and shortening to raw materials, the mixture were refined to 25 micron of particle size. Coating of Rice Cake were carried out at $65^{\circ}C$. SPI coated Rice Cake had higher internal and external firmness comparing to the control at $25^{\circ}C$. SPI coated Rice Cake showed smooth surface morphology and had 0.71-1.01 mm of thickness. SPI coated Rice Cake showed less weight loss for 30 days compared to controls. SPI coating solution was successfully coated on Rice Cake and extended shelf-life over 15 days at room temperature.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.9
• /
• pp.1285-1292
• /
• 2016

Changes in surface hydrophobicity of soy protein isolate (SPI), which plays an important role in the functional characteristics of protein, were measured according to various SPI concentrations, pH levels, electrolytes concentrations, and alginate molecular weights by using 1-anilino-8-naphthalene sulfonic acid as a fluorescent probe. SPI surface hydrophobicity decreased as SPI concentrations increased. SPI surface hydrophobicity reached a maximum at pH 7.0. SPI surface hydrophobicity rapidly increased as the NaCl concentration of SPI solution increased up to 100 mM, and showed no large increases above 100 mM. However, SPI surface hydrophobicity radically decreased until the $CaCl_2$ concentration reached 50 mM and revealed no large variations above 50 mM. A similar trend was exhibited in the case of $MgCl_2$. As both the concentration and molecular weight of sodium alginate increased, SPI surface hydrophobicity decreased. The increasing rate of SPI surface hydrophobicity decreased as the molecular weight of sodium alginate increased.

• Preventive Nutrition and Food Science
• /
• v.21 no.4
• /
• pp.338-347
• /
• 2016

The present study investigated the volatile compound, physicochemical, and antioxidant properties of beany flavor-removed soy protein isolate (SPI) hydrolyzates produced by combined high temperature pre-treatment and enzymatic hydrolysis. Without remarkable changes in amino acid composition, reductions of residual lipoxygenase activity and beany flavor-causing volatile compounds such as hexanol, hexanal, and pentanol in SPI were observed after combined heating and enzymatic treatments. The degree of hydrolysis, emulsion capacity and stability, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, and superoxide radical scavenging activity of SPI were significantly increased, but the magnitudes of apparent viscosity, consistency index, and dynamic moduli (G', G") of SPI were significantly decreased after the combined heating and enzymatic treatments. Based on these results, it was suggested that the enzymatic hydrolysis in combination with high temperature pre-treatment may allow for the production of beany flavor-removed SPI hydrolyzates with superior emulsifying and antioxidant functionalities.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.9
• /
• pp.1251-1255
• /
• 2006

To improve the water resistance and physical properties of soy protein isolate (SPI)-coated paper, effects of concentrations of soy protein isolate and plasticizer were examined. Physical properties such as elongation strength (ES), elongation rate (E), water vapor permeability (WVP), and water solubility (WS) were evaluated. The film made from 5% soy protein isolate (SPI) and 40% glycerol (plasticizer) suggested a good application for a film preparation. SPI coated paper showed the highest ES (21.62 MPa) and the lowest WVP $(2.06ng{\cdot}m/m^2{\cdot}s{\cdot}Pa)$ and WS (1.17%). This study suggested that soy protein isolate (SPI) can be used as a coating material for the coated paper to improve the water resistance.

• Composites Research
• /
• v.27 no.5
• /
• pp.196-200
• /
• 2014

A novel, simple and totally recyclable method has been developed for the synthesis of nontoxic, biocompatible and biodegradable bio-composite films from soy protein and silk protein. Bio films are defined as flexible films prepared from biological materials such as protein. These materials have potential application in medical and food as a packaging material. Their use depends on various parameters such as mechanical (strength and modulus), thermal, among others. In this study, prepare and characterization of bio films made from Soy Protein Isolate (SPI) (matrix) and Silk Fiber (SF) (reinforcement) through solution casting method by the addition of plasticizer and crosslinking agent. The obtained SPI and SPI/SF composites were subsequently subjected to evaluate their mechanical and thermal properties by using Universal Testing Machine and Thermal Gravimetric Analyzer respectively. The tensile testing showed significant improvements in strength with increasing amount of SF content and the % elongation at break of the composites of the SPI/SF was lower than that of the matrix. Though the interfacial bonding was moderate, the improvement in tensile strength and modulus was attributed to the higher tensile properties of the silk fiber.

• Journal of the Korean Home Economics Association
• /
• v.28 no.4
• /
• pp.41-50
• /
• 1990

Soy protein was isolated from Korean soy bean 'Chang ryub' and chemically modified with succinic anhydride. Functionality of the soy protein isolate(SPI), succinylated SPI(SPPI), and PP590(commercial) at various pH were investigated. The mechanical and sensory properties of soy bean curds made from several mixing ratio of succinylated soy bean milk were observed. The solubility of SPI significantly increased with succinylation. The solubility of PP590 was lower than that of SSPI. The solubility of SPPI increased significantly in 0.03M CaCl2 solution. The emulsifying activity of SSPI increased. On the range of pH above pI the emulsifying activity of PP590 was higher than that of SPI. There was no difference in emulsion stability among the groups. The foam expansion capacity of SPPI increased at higher pH than pI but the foam stability decreased significantly above pH 9. Mechanical texture profile analysis revealed the modified soy bean curds had the lower hardniss, chewiness and cohesiveness with increased modification. The mechanical characteristics of modified soy bean curds revealed generalized Maxwell Model of 7-elements or 5-elements. In sensory evaluation, the hardness, the springiness and acceptability of modified soy bean curds were lower significantly than those of control soy bean curd.

• Advances in materials Research
• /
• v.11 no.3
• /
• pp.191-209
• /
• 2022

Very slow degradation of synthetic based polymers has created a severe environmental issue that increased awareness towards research in polymers of biodegradable property. Soy protein isolate (SPI) is a natural biopolymer used as matrix in green composites but it has limitations of low mechanical properties and high water sensitivity. To enhance mechanical properties and reduce water sensitivity of Jute-SPI composites, SPI was modified with pine rosin which is also a natural cross-linking agent. 30% glycerol on the weight basis of a matrix was used as a plasticizer. The fibre volume fraction was kept constant at 0.2 whereas the pine rosin in SPI ranged from 5% to 30% of the matrix. The effects of pine rosin on mechanical, thermal, water sensitivity and surface morphology have been characterized using various techniques. The mechanical properties and water absorbency were found to be optimum for 15% pine rosin in Jute-SPI composite. Therefore, Jute-SPI composite without pine rosin and with 15% pine rosin were chosen for investigation through characterization by Fourier transforms infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), X-Ray diffraction (XRD) and Scanning electron microscope (SEM). The surface morphology of the composite was influenced by pine rosin which is shown in the SEM image. TGA measurement showed that the thermal properties improved due to the addition of pine rosin. Antimicrobial test showed antimicrobial property in the composite occurring 15% pine rosin. The research paper concludes that the modification of SPI resin with an optimum percentage of pine rosin enhanced mechanical, thermal as well as water-resistant properties of jute fibre reinforced composites.