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

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.05a
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• pp.250-253
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• 2004

본 연구는 Soy Protein Isolate, Egg Albumin 및 Konjac의 보습제(humectants)를 첨가하여 제조한 육포의 이화학적, 미생물학적 및 관능적 특성 등을 조사하기 위하여 실시되었다. 보습제를 첨가한 처리구들은 대조구보다 높은 수분함량 및 제품수율을 나타내었으며, 낮은 puncture force를 나타내어 우수한 조직감을 보였다. 모든 처리구가 저장기간이 경과함에 따라 지질산패도 및 총균수가 증가하였으나 konjac을 첨가한 처리구에서 대조구에 비해 다소 낮은 TBA가를 나타냈었다. 또한 Soy protein isolate와 konjac을 첨가한 처리구가 다른 처리구에 비해 낮은 총균수를 나타내었다. 따라서 보습제 종류별 육포의 품질에 미치는 영향이 다소 차이는 있었지만, 저장성면에서 육포 제조시 보습제로서 konjac 첨가가 보다 유효한 것으로 판단된다.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.457-461
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• 1992

The emulsion stabilizing properties of soy protein isolate (SPI) were investigated in terms of the protein and oil concentration. Particularly, the dependence of emulsion stability on the oil particle size and viscosity of emulsion was studied in conjunction with the adsorption pattern of protein onto the water/oil interface during emulsification. The data showed that increasing protein concentration decreased the oil particle size and increased the emulsion viscosity, resulting in the enhanced emulsion stability. In contrast, increasing oil concentration increased both the oil praticle size and the emulsion viscosity, and thus emulsion stability varied depending on which factor predominated the overall emulsion system.

• Korean journal of food and cookery science
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• v.21 no.2 s.86
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• pp.217-224
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• 2005

The storage characteristics of frozen soy yogurt prepared with hydrolyzed soy protein isolates were evaluated. In order to facilitate lactic fermentation bacteria grow and produce lactic acid as fast rate as possible, soy protein isolate(SPI) was hydrolyzed using two kinds of proteases; bromelain and a-chymotrypsin. The cultural systems employed thereafter for lactic fermentations were Bifidobacterium bifidum or B. bifidum and Lactobacillus bulgaricus. The viable cell counts, normal- and bile acid tolerances from the mixed cultures of B. bifidum and L. bulgaricus decreased sharply during the initial first 3 days of frozen storage and then showed a gradual decrease thereafter. Melt-down percent of the all frozen products have been favorably affected as was shown by less melting at raised testing temperature during 28 days of frozen storage except for the initial 3 days during which a minor change has been observed. Among the various volatile flavor components, the contents of acetaldehyde, acetone, diacetyl and methanol generally increased during the frozen storage. In sensory test, the frozen soy yogurt prepared with a-chymotrypsin and mixed culture of B. bifidum and L. bulgaricus was the most desirable, the highest scores in sourness, bitterness and mouthfeel.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.294-299
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• 1992

This study was to examine the effect of functional properties of soy protein isolate(SPI) and qualities of soybean curd upon proteolytic hydrolysis. SPI was hydrolyzed using proteolytic enzyme, bromelain. The protein content of SPI by microkjeldahl method was 84% and the degree of hydrolysis in modified soy protein isolate(MSPI) was 2.7%. The solubility of MSPI was higher than that of control at various pH tested and proteolytic hydrolysis was increased emulsion formation and foam expansion while decreased emulsion stability, foam stability and calcium precipitation. Modified soybean curdI, standard soybean milk: Modified soybean milk=3:1, was soft and springy soybean curd when the texture properties of soybean curd were tested by texture profile analysis using Instron and sensory evaluation. The rheological model of soybean curds was investigated by stress relaxation test. The analysis of relaxation curve revealed that the rheological behavior of soybean curds could be expressed by 7-element generalized Maxwell model. The equilibrium modulus and modulus of elasticity decreased as the ratio of modified soybean milk was increased.

• Journal of Nutrition and Health
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• v.34 no.8
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• pp.833-842
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• 2001

The purpose of this study is to determine the effect of dietary proteins and fats on the hepatic histological changes, membrane stability, and drug-metabolizing enzyme activities during chemically induced rat hepatocarcinogenesis. Weanling Sprague-Dawley rats were fed the diet containing 20% casein or soy protein isolate and 15% perilla or corn oil for 10 weeks. Hepatocarcinogensis was initiated with diethylnitrosamine(DEN), and the rats were fed diets containing 0.02% 2-acetylaminofluorene(AAF) followed by 0.05% phenobarbital (PB). The scores of histological changes were decreased in treated rats fed soy protein diet compared to those find casein diet. Liver weights were significantly increased by AAF and PB treatment in rats fed casein diets in both oil groups. Glucose 6-phosphatase(G6Pase) activities, an index of membrane stability, were significantly reduced by AAF and PB treatment in rats find casein diets, and were lower in casein diet compared to soy protein diet groups. Especially, the activities were the highest in the rats fed soy protein-perilla oil diet. Lipid peroxide values also were increased by AAF and PB treatment in rats fed casein diet. Aniline hydroxylase activities were not influenced by protein and fat sources. Glutathione-dependent enzyme activities were increased by AAF and PB treatment. Linoleic and arachidonic acid content were increased in rats fed corn oil diet, and linolenic and eicosapentaenoic acid contents were increased in rats fed perilla oil diet. Our results suggest that soy protein isolate inhibit the abnormal histological changes in liver, possibly by maintaining the membrane stability during chemically induced rat hepatocarcinogenesis. Soy protein may be protective against the hepatocarcinogenesis induced by chemical carcinogen.

• Journal of Nutrition and Health
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• v.43 no.4
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• pp.342-350
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• 2010

This study was aimed to investigate whether soy protein hydrolysates had beneficial effects on serum and tissue lipid contents and appetite-related hormones as compared with intact soy protein. Four-week-old male Sprague-Dawley rats were fed AIN-93M diet containing high fat (18% w/w) with low protein (10% w/w). After four weeks, the rats were divided into four groups (n = 8/group) and fed experimental diets with different nitrogen sources and levels, respectively; 10% soy protein isolate (10SPI), 25% soy protein isolate (25SPI), 25% soy protein hydrolysates (25SPH) and 25% soy macro-peptide fractions (25SPP, MW $\geq$ 10,000) for six weeks. Weight gain was significantly higher in 25% nitrogen sources-fed groups than in 10% group (10SPI). In 25SPP, perirenal fat mass and serum total lipid were significantly lower than in other groups. As for appetite-related hormones, serum ghrelin concentration was not shown to be different among groups but leptin concentration was significantly decreased in 25SPP. It can be concluded that soy macro-peptide fractions as compared with intact soy protein may have beneficial effects on reducing fat mass and serum lipid.

• Journal of Nutrition and Health
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• v.35 no.4
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• pp.409-413
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• 2002

The purpose of this study was to determine to which differences in the source of protein (soy vs casein) and of isoflavones in soy protein are responsible for differential effects of bone mineral density and bone mineral content. Thirty 21-d-old Sprague-Dawley young rats were divided into 3 groups: the control group was find a casein-based diet, the soy concentrate group was fed soy protein with totally reduced isoflavones content (isoflavone 0.07 mg/g protein), and soy isolate group was fed with a higher isoflavone content (isoflavone 3.4 mg/g protein) than normal. The animal was scanned to determine the BMD and BMC using dual energy X-ray absorptiometry (DEXA, Lunar Corporation, Madison, WI). The soy concentrate group had significantly higher total body calcium/weight and total mineral content/weight than the casein group. The soy isolate group had significantly greater total bone mineral density/weight, spine bone mineral density/weight, and femoral bone mineral density (in g/$\textrm{cm}^2$ than the control and soy concentrate group. The findings of this study suggest that soy protein and isoflavones in soy protein are beneficial for bone-formation in growing male rats. Therefore exposure to these soy protein and isoflavones early in life may have long-term health benefits for bone diseases such as osteoporosis.

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

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.3
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• pp.99-104
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• 2009

Soy protein isolate (SPI)-based nanocomposite films with three different types of nanoclays, such as Cloisite $Na^+$, Cloisite 20A, and Cloisite 30B, were prepared using a solution casting method, and their optical, tensile, and water vapor barrier properties were determined to investigate the effect of nano-clay type on film properties. Among the tested nanoclays, Cloisite $Na^+$, a hydrophilic montmorillonite (MMT), exhibited the highest transparency with least opaqueness, the highest tensile strength, and the highest water vapor barrier properties, indicating Cloisite $Na^+$ is the most compatible with SPI polymer matrix to form nanocomposite films. The film properties of SPI/Cloisite $Na^+$ nanocomposite films were strongly dependent on the concentration of the clay. Film properties such as optical, tensile, and water vapor barrier properties improved significantly (p<0.05) as the concentration of clay increased. However, the effectiveness of addition of the clay reduced above a certain level (i.e., 5wt%), indicating that there is an optimum amount of clay addition to exploit the full advantage of nanocmposite films.