• Journal of Applied Biological Chemistry
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• v.42 no.3
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• pp.125-129
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• 1999

The changes in gel characteristics of soy protein and succinylated soy protein due to various specific interaction-altering reagents which affect the formation and textural properties of gels, were studied. The reagents were added to 15% soy protein solutions prior to heat treatment. Succinylated soy protein formed harder gel without the addition of reagents. Hardly no gels were formed with urea, indicating that hydrogen bonds significantly contributed to the formation and hardness of the gel and the effects of urea on the hardness of succinylated soy protein gel were more significant. Disulfide bonds were important in the formation of hard gels whether they were succinylated or not, but the contributions of hydrophobic interactions to gel hardness were relatively insignificant. The hardness reducing effects of NaCl and NaSCN were more significant in succinylated soy protein gel. As such, electrostatic interactions were important for succinylated soy protein to form hard gel but not for unmodified soy protein.

• Food Science of Animal Resources
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• v.43 no.6
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• pp.1031-1043
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• 2023

The purpose of this study was to investigate the functional properties of salt-soluble proteins obtained from Protaetia brevitarsis (PB) and Tenebrio molitor (TM) larvae, the interaction between these proteins and pork myofibrillar protein (MP) in a gel system. The gel properties of salt-soluble protein extracts showed that the PB had a higher viscosity than the TM protein. However, the TM protein had higher gel strength compared with the PB protein. The gelation characteristics of the pork MP gel systems added with lyophilized insect salt-soluble protein powder showed to decrease slightly viscosity compared with MP alone. Adding the TM or PB protein powder did not affect the pork MP's hydrophobicity and sulfhydryl group levels. Furthermore, the protein bands of the MP did not change with the type or amount of insect salt-soluble protein. The cooking yields of the pork MP gels containing PB or TM protein powder were higher than those without insect protein. Regardless of the type of insect salt-soluble protein added, the pork MP's gel strength decreased. Furthermore, as the level of insect powder increased, the surface protein structure became rough and porous. The results demonstrated that proteins extracted from PB and TM larvae interfered with the gelation of pork MP in a gel system.

• Food Science and Preservation
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• v.5 no.1
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• pp.65-71
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• 1998

The changes in gel characteristics of soy protein as a result of various reagents that alter specific interactions which affect the formation and textural properties of gels, were studied. The reagents were added to 15% soy protein solutions prior to heat treatment. The gels were not formed with urea, indicating that hydrogen bonds significantly contributed to the formation and hardness of soy protein gel. Hydrophobic interactions and disulfide bonds compensated for hydrogen bonds and the contributions of electrostatic interactions to gel hardness are relatively insignificant. The farce primarily responsible for gel cohesiveness appeared to be disulfide bonds, because a significant decrease in cohesiveness was found only with the presence of N-ethylmaleimide. Adhesiveness decreased only with the addition of urea, and thus the contribution of hydrogen bonding to adhesiveness of gel could be concluded to be resent. However, adhesiveness was suggested to be interpreted not only wile molecular forces involved in gel formation but also with hydration properties of protein.

• Korean Journal of Food Science and Technology
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• v.23 no.4
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• pp.428-432
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• 1991

This study was carried out to investigate the effect of NaCl, pH and phosphate on the functional properties of a mixed system of plasma protein and myofibrillar proteins. The solubility of plasma protein, myofibrillar protein and the mixture (plasma+myofibrillar protein) increased according to the increase of NaCl concentration ($0{\sim}4%$) and pH $pH4{\sim}8$). The solubility, emulsifying activity and capacity of the mixture were lower than those of plasma protein, whereas higher than those of myofibrillar protein. The gel strength of the mixture and myofibrillar protein showed a significant increase when NaCl concentration was increased from 2 to 3%. The gel strength of myofibrillar protein increased about four times when 0.3% polyphosphate added to the sample containing 2% NaCl, whereas the moisture loss of the mixture and myofibrillar protein decreased significantly. The gel strength of plasma protein, myofibrillar protein and the mixture increased slightly at $3{\sim}5%$ protein concentration, whereas the gel strength of those increased significantly as the protein concentration increased from 5 to 9%.

• Korean Journal of Food Science and Technology
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• v.2 no.2
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• pp.49-55
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• 1970

In preparation of textured soybean protein, drying process of the isolated protein affected its gelling property and other related characteristics such as water holding capacity and viscosity. In model systems, denaturation of the protein, as determined in terms of nitrogen solubility index (NSI), was appeared to be a parameter of the gel strength of soybean protein isolate. The gel strength was maximum when the protein was denatured properly during drying process of which the NSI was 43 in this experiment and decreased at either the higher or the lower NSI. It indicated that proper denaturation of the protein during drying operation is advantagous for the preparation of textured soybean protein but not neccesary to make highly undenatured one.

• YAKHAK HOEJI
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• v.35 no.6
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• pp.461-465
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• 1991

Silica-based gel filtration chromatography has been used to characterize molecular weight of proteins. However, the molecular weight measured by this method was distorted by protein-silica interactions like hydrophobic and electrostatic forces. Therefore, we characterized protein-silica interaction using two forms of phytochrome (124 kDa) having different hydrophobicity and surface charge. PH and ionic strength affected the retention time of phytochrome suggesting that electrostatic force is the major interaction between protein and silica surface.

• Korean Journal of Food Science and Technology
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• v.25 no.3
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• pp.295-298
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• 1993

This study was carried out to investigate the effects of heating temperature, heating time and protein concentration on the gel properties and heat stability of a mixed system of pork plasma and myofibrillar to increase the utility of porcine blood as protein resources of the food industry, especially meat processing industry. The solubility of plasma protein and mixture (plasma + myofibrillar protein) decreased significantly at $70^{\circ}C\;to\;90^{\circ}C$ when heating temperature rised, whereas myofibrillar protein decreased slightly at $40^{\circ}C\;to\;60^{\circ}C$, and the gel strength and the turbidity of those increased significantly at these heating temperatures. The solubility of plasma protein and mixture decreased when the heating time increased at $75^{\circ}C$, whereas the gel strength and turbidity increased, and the solubility, the gel strength and the turbidity of myofibrillar protein showed no changes.

• Korean journal of applied entomology
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• v.37 no.1
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• pp.59-64
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• 1998

A juvenile hormone binding protein (JHBP) has been isolated from the whole body homogenate of Galleria rnellonella final instar larvae by gel filtration. The isolated protein is homogenous as judged by column chromatography and gel electrophoresis in the presence and absence of denaturing agent. The JHBP has a relative molecular weight of 32 k by denaturing gel electrophresis and 28 k by gel filtration. The protein exhibits a dissociation constant of 3.9 x M for JH 111.

• Journal of Applied Biological Chemistry
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• v.51 no.3
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• pp.88-94
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• 2008

Three different protein extraction methods-phenol extraction, trichloroacetic acid (TCA) precipitation, and desalting/TCA precipitation-were compared to determine the optimal reproducible high resolution 2-dimensional (2-D) electrophoresis for each chungkugjang, doenjang, and kochujang samples. The soluble proteins from Chungkugjang extracted by phenol were separated with high reproducibility and resolution, and gained 1.75- to 3-fold more protein spots on 2-D gel than those from the other methods. On the contrary, the extracted proteins from doenjang and kochujang treated by desalting/TCA precipitation method showed about 1.5- to 3.3-fold more protein spots on 2-D gel. Using the established methods, the changes in the protein profiles of the fermented soy foods were monitored during the fermentation period by 2-DE. One of the major proteins in soy, $\beta$-conglycinin $\alpha$-subuint, and some proteins with unknown functions were localized on 2-D gel as the protease-resistant proteins throughout the fermentation period of doenjang. Changes in the protein profile monitored by the established methods can provide basic information on unfolding the mechanisms of the generation of biofunctional activity in the fermented soy foods.

• Korean journal of food and cookery science
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• v.12 no.4
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• pp.571-576
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• 1996

The moisture-dependent gelation characteristics of five different proteins are evaluated to understand the modification of gel strength when they are added in surimi gel. Compressive force and penetration force of protein gels gradually decreased with increase of moisture level, with showing markedly decrease at certain point of moisture level called critical moisture level. The critical moisture level for gelation of SPI-1, SPI-2, EW, WPC and LA were 79.4%, 81.6%, 91.4％, 87,8% and 84.7%, respectively. Beyond this critical level of water, protein gel matrix begins to lose its water binding and structural integrity. The mnisture that was not re tained by a protein was available to diluting the protein matrix and eventually weakened the overall gel strength. EW and MPI showed higher water retention than those of SPI, WPC and LA. The compressive force of SPI, WPC and LA-incorporated surimi gel at the varying moisture levels strongly correlated with the amount if water retained at corresponding moisture level within those protein (r=0.99).