• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.2
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• pp.154-162
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• 2006

Cheese analogs using lipoxygenase-defected soymilk and ${\alpha}$-chymotrypsin modified soy protein isolate (SPI) were prepared. Color, textural properties, sensory attributes and melting spreadability of cheese analogs were evaluated and compared with mozzarella cheese, and relationships between textural properties, sensory attributes and melting spreadability of cheese analogs were analyzed. Off-flavors were not mostly discriminated. Cheese analogs containing 10% SPI untreated and containing 6% and 8% SPI treated by ${\alpha}$-chymotrypsin in ${\Delta}E$ value of color were the most similar to mozzarella cheese. Quality characteristics and melting spreadability of cheese analogs were highly affected and improved by ${\alpha}$-chymotrypsin modification. Sensory attributes and melting spreadability of cheese analogs containing 6% SPI treated by ${\alpha}$-chymotrypsin were the most similar to mozzarella cheese, while in textural properties, cheese analogs containing 10% SPI were the most similar with mozzarella cheese. Hardness in sensory attributes was highly positively correlated with hardness (r>0.65), adhesiveness (r>0.56), chewiness (r>0.77) and gumminess (r>0.76) in textural properties, while it was highly negatively correlated with melting spreadability (r>-0.68).

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

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.8
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• pp.1135-1142
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• 2017

Objective: The objective of this study was to evaluate effects of heat treatment and soybean oil inclusion on protein oxidation of soy protein isolate (SPI) and of oxidized protein on redox status of broilers at an early age. Methods: SPI mixed with soybean oil (SPIO) heated at $100^{\circ}C$ for 8 h was used to evaluate protein oxidation of SPI. A total of two hundred and sixteen 1-day-old Arbor Acres chicks were divided into 3 groups with 6 replicates of 12 birds, receiving basal diet (CON), heat-oxidized SPI diet (HSPI) or mixture of SPI and 2% soybean oil diet (HSPIO) for 21 d, respectively. Results: Increased protein carbonyl, decreased protein sulfhydryl of SPI were observed as heating time increased in all treatments (p<0.05). Addition of 2% soybean oil increased protein carbonyl of SPI at 8 h heating (p<0.05). Dietary HSPI and HSPIO decreased the average daily gain of broilers as compared with the CON (p<0.05). Broilers fed HSPI and HSPIO exhibited decreased glutathione (GSH) in serum, catalase activity and total sulfhydryl in liver and increased malondialdehyde (MDA) and protein carbonyl in serum, advanced oxidation protein products (AOPPs) in liver and protein carbonyl in jejunal mucosa as compared with that of the CON (p<0.05). Additionally, broilers receiving HSPIO showed decreased glutathione peroxidase activity (GSH-Px) in serum, GSH and hydroxyl radical scavenging capacity in liver, GSH-Px activity in duodenal mucosa, GSH-Px activity and superoxide anion radical scavenging capacity in jejunal mucosa and increased AOPPs in serum, MDA and protein carbonyl in liver, MDA and AOPPs in jejunal mucosa (p<0.05). Conclusion: Protein oxidation of SPI can be induced by heat and soybean oil and oxidized protein resulted in redox imbalance in broilers at an early age.

• Korean Journal of Food Science and Technology
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• v.9 no.3
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• pp.190-193
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• 1977

In our previous report (Korean J. Food Sci. and Technol., 9, 123, 1977) we have studied the functional properties of soy protein isolates prepared from defatted soybean meal. For the practical application of the data described, beef patties substituted with SPI, and imitatied ice cream were prepared and sensory evaluations were carried out. The sensory analyses indicated that the beef patties substituted with gelated SPI to 30% have no detectable difference to the control at the significant level of 0.01. The imitation of ice cream whose milk-solid-not-fat was substituted with soy protein isolates showed the same texture as the control. Flavor of ice cream, however, has significant difference to the control due to beany-off flavor. Therefore removal of beany-off flavor is required for the substitution in ice cream.

• Korean journal of food and cookery science
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• v.15 no.1
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• pp.73-80
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• 1999

This study was carried out to investigate the effects of enzyme treatments on the functional properties of soy protein isolate (SPI) and to examine the quality attributes of soy yogurt prepared by different enzyme treatments, sweeteners and starter cultures. Enzyme treatment increased the solubility and emulsifying capacity of soy proteins, but decreased the emulsifying stability; the enzymatic activity of ${\alpha}$-chymotrypsin was higher than that of trypsin. Enzyme treatments decreased the pH of soy yogurts prepared by both culture methods, the culture of L. bulgaricus and S. thermophilus and the culture of L. bulgaricus and K. fragilis, but increased the titratable acidity, total numbers of lactic acid bacteria and yeast. Trypsin was more effective than ${\alpha}$-chymotrypsin in decreasing pH and increasing titratable acidity and total numbers of lactic acid bacteria and yeast. Fructose decreased the pH of soy yogurts more than sucrose in the culture of L. bulgaricus and S. thermophilus, and vice versa in the culture of L. bulgaricus and K. fragilis. Fructooligosaccharides were more effective in the culture of L. bulgaricus and K. fragilis than in the culture of L. bulgaricus and S. thermophilus in increasing the titratable acidity, total count of lactic acid bacteria and yeast. In sensory evaluation, soy yogurts containing trypsin treated SPI, fructose and fructooligosaccharides (75%:25%) were more acceptable than those containing untreated or trypsin treated SPI and fructose. This was because of more smooth and less sour, in which the values of pH, titratable acidity, microbial growth, and viscosity were in the range of commercial yogurts. Soy yogurts fermented by L. bulgaricus and K. fragilis showed more smooth mouthfeel than those fermented by L. bulgaricus and S. thermophilus.

• Korean Journal of Food Science and Technology
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• v.38 no.4
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• pp.534-542
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• 2006

The protein contents of soy protein isolate (SPI) and soft wheat flours were 83.5% and 8.5%, respectively. The addition of SPI increased the protein content but decreased the sedimentation value. Alkaline water retention capacity (AWRC) value increased with SPI addition and was highly correlated with protein content. Increasing SPI flour content significantly decreased the maximum, minimum and final viscosities. Mixograph peak time was positively correlated with protein content and AWRC. The PH and specific gravity of the cake batter increased with increasing SPI content. The SPI addition reduced the loaf and specific loaf volume compared with soft wheat flour. The lightness of the cake crust decreased, while the redness and yellowness increased, with SPI flour addition. SPI addition resulted in a decrease of overall acceptability, but an increase in hardness.

• Korean Journal of Food Science and Technology
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• v.23 no.3
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• pp.286-290
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• 1991

Phytic acid known as an antinutritional facfor was studied for its effect on the solubility and digestibility of high-phytate and low-phytate soy protein isolates (SPI) obtained by two different methods of pH adjustment. Phytic acid content was 2.48% in high-phytate SPI and 0.72% in low-phytate SPI. Solubility of soy proteins was higher in low-phytate SPI than in high-phytate SPI at all pH values tested and it was lowered by adding more phytic acid to result in precipitation of the proteins. The inhibitory effect of phytic acid toward pepsin digestion of SPI increased by the increasing amount of phytic acid added and its effect was slightly higher in high-phytate SPI than in low-phytate SPI.

• 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.

• Journal of Applied Biological Chemistry
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• v.55 no.1
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• pp.27-34
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• 2012

Soy protein isolate (SPI)-based edible coating, with and without carboxymethyl cellulose (CMC), were used to reduce oxidative degradation of cut pork stored at $4^{\circ}C$ for 5 days. The SPI coating reduced (p<0.05) thiobarbituric acid-reactive substances (TBARS) and peroxide value (PV), compared with controls. The inhibition of TBARS and PV for SPI-coated porks with and without CMC, compared with the control was 19.1 and 23.9, and 25.7 and 37.7%, respectively. The SPI coating prevented loss of $L^*$ and $a^*$ values of porks compared to the control. The ability of the SPI coating to provide a moisture barrier for the porks was reduced (p<0.05). The SPI-coated porks with and without CMC reduced moisture loss by 37.3 and 44.6%, respectively, over the control. However, SPI coating of porks did not inhibit the growth of either total plate counts or L. monocytogenes. The result revealed that SPI can effectively be used as a natural antioxidative coating to extend quality and shelf life of pork.

• 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.