• The Korean Journal of Food And Nutrition
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• v.7 no.3
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• pp.177-182
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• 1994

The effect of phosphate salt (NafHP04) and sodium citrate on the emulsion stability of soy protein isolate (SPI) in the presence of calcium was investigated in terms of salt concentration and addition order. Both phosphate and citrate salts decreased the solubility of SPI despite their pH enhancing effects. Addition of calcium chloride (CaCl2) significantly decreased ES, which showed nearly negligible at more than 3 mM CaCl2 concentration. When Na2HP04 were added in the presence of 5 mM Cac12, 55 greatly increased up to 20mM concentration, above which however ES decreased. It was found that the addition order of Na2HPO4 and CaCl2 affected ES. The addition of phosphate and subsequent CaCl2 exhibited the higher 55 than the reverse order. In both cases, the overall ES profile was found to be nearly similar to the solubility profile of SPI, indicating the positive relationship between solubility and emulsion stability of SPI in the presence of calcium. Similar trend to the phosphate effect on ES was also observed for sodium citrate in the presence of calcium.

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

• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.386-392
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• 1990

Soybean proteins of 19 varieties recommended In Korea were characterized by solubility classes, SDS-PAGE and amino acid composition. In distribution of the protein fractions by solubility difference, glycinin content was $48.19{\sim}58.86%$ of total protein. Prolamin, constituting about 1.16% of total protein, was the fraction showing the significant differences between varieties. The electrophoretic patterns of whole soybean proteins exhibited no varietal differences except in 6 varieties of Padal, Jangbaek, Jangyeob, Danyeob, Nameheon and S-138 in molecular weight range of $21.5{\sim}31.0%$ kd. Cystein, methionine, tyrosine and threonine were the minor components of soybean protein and percentage of tyrosine to the total proteins showed significant varietal differences.

• Korean Journal of Food Science and Technology
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• v.17 no.5
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• pp.383-388
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• 1985

Soy protein isolate was acylated with succinic anhydride and acetic anhydride. The functional properties are markedly improved by acylation of the $\varepsilon$-amino groups. Acylation of the available amino groups shifted the isoelectric point from 4.5 to 4.0 and enhanced the solubility between pH 4.0-6.0. In the 0.03M-$CaCl_2$ solution the solubility of the modified soy protein is much larger than that of the unmodified protein above the isoelectric point. The emulsion properties and foaming properties also improved by the modification and the effects of pH on the properties paralleled its effect on protein solubility. The changes of reduced viscosity with concentration followed Huggin's equation and by modification the intrinsic viscosity of the soy protein increased and the interaction coefficient decreased.

• Applied Biological Chemistry
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• v.31 no.4
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• pp.382-386
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• 1988

Extracellular protein produced by Bacillus sp. $T_2-3$ was characterized for its patterns of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and sephadex G-100 filtration, spectrum of maximum absorption, composition of amino acid and solubility to solvents. The extracellular protein was composed of two kinds of protein which was little difference in molecular weight about 49,000. Maximum absorbance of the extracellular protein was showed at 230nm and main amino acids of the extracellular protein were aspartic acid, glutamic acid and alanine. Solubility of the extracellular protein was 55.8% in $H_2O$ and 28.4% in 0.4% NaOH.

• Korean journal of food and cookery science
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• v.20 no.3
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• pp.256-264
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• 2004

The effects of irradiation on the functional and structural characteristics of soy protein isolates were studied. Soymilk was irradiated at 1, 5, and l0kGy, after which soy protein isolates were prepared. The functional properties of soy protein isolates were examined including solubility, emulsion capacity and stability, foam capacity and stability, structural properties as represented by SDS-PAGE pattern, and secondary and tertiary structures. The solubility and emulsion capacity were increased by radiation treatment at 1kGy however the values were adversely affected again as dosage was increased above 5kGy. As irradiation dosage increased, an increase of foaming capacity at 1kGy and a decreasing turnover afterwards were also noted in foaming capacity, although the differences were not statistically significant. The SDS-PAGE pattern showed fragmentation and aggregation of protein molecules as affected by irradiation in proportion to the dosage increase. The results of CD and fluorescence spectroscopy revealed increased aperiodic structure contents with the dosage increase. It was assumed that irradiation dosagefrom 5 to l0kGy could initiate minimal denaturation of protein in various foods compared to general heat treatment.

• Korean journal of food and cookery science
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• v.9 no.1
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• pp.43-51
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• 1993

Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.658-664
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• 1999

Broiler and porcine blood plasma were desugarized by GOD (glucose oxidase 10 units/g) or baker's yeast (0.3% w/w) and dried. The color, biuret protein content, solubility, foaming capacity and pH of desugarized blood plasma powder during storage at room temperature were investigated. Desugarized plasma powder was lighter and less red and yellow than the control group (P<0.05). Biuret protein content and solubility of deglucosed plasma powder were higher than the control. Biuret protein content and solubility of all samples decreased during storage (P<0.05). Generally, deglucosed samples showed better foaming capacity than the controls (P<0.05). The pH of deglucosed broiler samples by yeast and porcine samples were decreased just after initial increasing, while the pH of other broiler powder was continuously decreased during storage. Deglucosed porcine powder always showed higher pH values than the control (P<0.05). Overall, desugatization of broiler or porcine blood plasma before drying improved color, biuet protein content, solubility and foaming capacity.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.35-39
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• 1998

An enzymatic process was developed to produce protein hydrolysater form defatted soya protein. Various unit operations were tried, and the effects of pre- and post-treatments on the product characteristics such as degree of hydroylsis (DH), free amino acid content (%FAA) and average molecular weight (MW) were investigated. The use of acid washes showed no difference in %DH. Increasing pH during pre-cooking gave lower %DH. Alkaline cooking made too much insoluble protein, thus the protein yield was too small. A better hydrolysis with more acceptable taste was obtained when the combination of Neutrase/Alcalase/Flavourzyme was used in place of Alcalase/Flavourzyme combination; Untoasted defatted soya was more effective on the proteolysis than toasted one. The MW of the evaporated and spray dried product was higher than that of undried product, due to precipitation of low-solubility components. When ultrafiltration and the product concentration carried out the product separation by reverse osmosis, the solubility and the taste of the product were improved. The difference between enzyme hydrolysate and acid hydrolysate was significant in free amino acid composition, especially in tyrosine, phenylalanine, glutamine and asparagine.

• Journal of the Korean Magnetic Resonance Society
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• v.17 no.1
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• pp.30-39
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• 2013

Immortalization-upregulated protein-1 (IMUP-1) genes have been cloned and are known to be involved in SV40-mediated immortalization. IMUP-1 gene is highly expressed in various cancer cell lines and tumors, suggesting the possibility that they might be involved in tumorigenicity. Previously, there were several problems for overexpression of IMUP-1 in bacterial expression systems including low solubility and aggregation due to unstructured property. To investigate the structural properties, it is necessary to obtain lots of pure and soluble proteins. Accordingly, the co-expression systems of bacterial chaperone proteins, GroEL-GroES, were used to increase solubility of IMUP-1. From the analysis of NMR and CD experiment data, it is suggested that the protein adopt typical the random coil properties in solution.