• The Korean Journal of Food And Nutrition
• /
• v.27 no.1
• /
• pp.89-98
• /
• 2014

In this study, soybean is used to produce soymilk according to various extracting methods and heating time. Specifically, the soy slurry is being filtered before being heated, or heated before being filtered. Following that the soymilk produced is freeze-dried to be powdered, and then, the quality characteristics of the powdered soymilk are mutually compared to determine the applicability of various food additives. The freeze-dried soymilk powder shows 2.03~6.35% of moisture content, and in terms of unit quantity, retained more proteins, which suggests that the ratio of protein extraction is higher than any other nutrients. Accordingly, the protein coefficient is significantly higher in soymilk powder being heated and processed than in raw soybeans. In particular, protein coefficient is the highest in the soymilk which is heated for 20 minutes before being filtered (SHBF20). The longer the heating time was, the trypsin inhibitor (TI) tended to be far less active. Such an inactivation seems to be more apparent in the "SHAF" soymilk powder than "SHBF" soymilk powder. Because protein had to be denaturated by heating for soymilk, the nitrogen solubility index (NSI) of soymilk powder is decreased considerably, while the protein digestibility, water absorption, emulsification and foaming activity all increase. Oil absorption tends to decrease slightly. As discussed above, the soymilk heated for 10 minutes after being filtered (SHAF10) and the soymilk heated for 20 minutes before being filtered (SHBF20) show optimum processing conditions for soymilk powder.

• Journal of Nutrition and Health
• /
• v.28 no.10
• /
• pp.986-994
• /
• 1995

This study was to examine the effect of phytate on the protein digestibility and calcium, iron and zinc availability in phytase treated soymilks digested with pepsin and pepsin-pancreatin in vitro. Also, the bending between phytate and protein in soymilks was investigated by means of SDS-PAGE. The content of phytate in soymilk was reduced by phytase treatment. As the content of phytate decreased, the protein digestibility increased in soymilk treated with the digest enzymes in vitro. The reduction of phytate content in soymilk improved the availability of all calcium, iron and zinc. Although the availability of calcium increased, the amount of change was small. The phytate reduction increased most the availability of iron. A number of bands of high molecular weight protein in soymilk disappleared in SDS-PAGE by lowering the phytate content with phytase treatement on soymilk.

• Food Science and Preservation
• /
• v.15 no.6
• /
• pp.903-908
• /
• 2008

This study investigated protein changes in soymilk and whole soymilk due to enzymatic hydrolysis. The total free amino acid contents of low molecular weight soymilk (LSM) and low molecular weight whole soymilk (LWSM) were higher than soymilk (SM) and whole soymilk (WSM). The essential amino acid content was similar in SM and LSM, but was higher in LWSM than WSM. In SDS-PAGE performed to tendency of becoming low molecules, the soy protein molecular weights were 3372 kDa for SM and WSM, but 17 kDa or less for LSM and LWSM. Also, high molecular weight protein spots were evident in 2-D electrophoresis of SM and LSM, but only low molecular weight protein spots of various sizes were evident in WSM and LWSM. This suggests that the high molecular weight protein in SM and WSM is changed to low molecular weight protein by enzymatic hydrolysis. Further investigations of the separation and qualities of these proteins are required.

• Applied Biological Chemistry
• /
• v.35 no.6
• /
• pp.501-506
• /
• 1992

Pepsin-catalyzed hydrolysis and plastein reaction were carried out to prepare plastein product from soymilk residue protein. Conditions required for optimal hydrolysis of soymilk residue protein and subsequent plastein production were investigated. The optimum substrate concentration, enzyme-substrate ratio, pH, reaction temperature and incubation time for hydrolysis were 3%, 1/50, 1.7, $45^{\circ}C$ and 24 hours, respectively. Plastein formation from peptic hydrolysate of soymilk residue protein was most effective at substrate concentratin of 40%, pH 4 and $45^{\circ}C$. Reaction time of 18 hours and enzyme-substrate ratio of 1/100 were selected for plastein production. Electrophoresis of the products revealed that protein-like substances of high molecular weight were produced from the plastein reaction.

• The Korean Journal of Food And Nutrition
• /
• v.19 no.4
• /
• pp.381-391
• /
• 2006

The rheological properties of dough made the substitution of wheat flour(composite flour) at the levels of 0%, 5%, 10% and 15% soymilk residue flour, with addition of vital wheat gluten at the levels of 3, 6 and 9% were investigated. And nutrition contents of soymilk residue flour were analyzed. The results were as follows; Principal components of soymilk residue flour were 22.0% crude protein, 13.2% crude lipid, 54.3% carbohydrate, 27.2% dietary fiber and $220{\mu}g/g$ isoflavones. Free amino acid component of soymilk residue were L-glutamic acid, L-leucine, L-lysine, L-valine, L-phenylalanine, L-isoleucine, L-threonine, L-methionine and L-cystine. Total dietary fiber content of bread with soymilk residue and wheat flour were 5% soymilk residue; 3.50%, 10% soymilk residues; 4.65%, 15% soymilk residues; 5.96%, and wheat flour bread: 2.1% respectively Mixing water absorption capacity was increased by increasing amounts of added soymilk residue and vital wheat gluten. Dough development time was increased by increasing amounts of added soymilk residues, while decreased by increasing amounts of vital wheat gluten. The dough volume of composite flour with 5%, 10% and 15% soymilk residue flour were the smaller than wheat flour dough. But the dough volume was increased by added vital wheat gluten, and the composite flour with 5% soymilk residue flour and 9% vital wheat gluten was better than the others. This study proved that the dough volume of composite flour with 5% soymilk residue flour and 9% vital wheat gluten was better than the others. On the other hand, the soymilk residue flour contains dietary fiber, isoflavone, protein, lipid and carbohydrate. Therefore the soymilk residue flour will be very useful as food material.

• The Korean Journal of Food And Nutrition
• /
• v.15 no.4
• /
• pp.331-336
• /
• 2002

Conformation of soymilk protein was examined to obtain basic information for improved calcium intolerence of soymilk protein partially hydrolyzed with protease. Surface hydrophobicities of three proteins showed the order of SMP(soymilk protein) < SPI(soy protein isolate) < PT-SMP(protease treated soymilk protein). Total thiol group contents of SMP and PT-SMP were similar but larger than that of SPI. Reducing rate of disulfide bond in PT-SMP after 2-mercaptoethanol treatment was laster than that in SMP. And so, this result indicates that PT-SMP may be less compacting due to protease treatement. From circular dichroism result, PT-SMP showed different pattern from SMP and SPI suggesting change of secondary structure by hydrolysis. And analysis of heat denaturating property by DSC showed that denaturation enthalpy of three proteins were all small. Especially enthalpy of PT-SMP was least, and this result suggested that PT-SMP was denatured easily by heating due to less compacting structure.

• The Korean Journal of Food And Nutrition
• /
• v.14 no.6
• /
• pp.562-567
• /
• 2001

In order to utilize okara protein as a food auditive, nutritional composition of soymilk okara was investigated. Protein in okara Is highly insoluble due to excessive heat treatment during soymilk processing. Protein content of okara was 37.3% as compared to 42.5 % for soybean. Carbohydrate and lipid contents of okara were 40.6% and 17.9%, respectively. Okara lipid extracted with chloroform-methanol consisted of neutral lipid, glycolipid and phospholipid, with neutral lipid making up 98.6% . Linoleic acid, ileic acid, and palmitic acids accounted for about 80% of the total fatty acids with linoleic acid sharing 50.3% of the total. Amino acid composition of okara protein was dissimilar to that of soy Protein : Cysteine was totally absent in okara while lysine, which is the limiting amino acid of soy protein, was present in higher amount in okara on dry weight basis. Both aqueous extract of okara protein and soy Protein were found to have ACE inhibitory activity.

• The Korean Journal of Food And Nutrition
• /
• v.7 no.4
• /
• pp.345-352
• /
• 1994

High protein beverage of cow-soy milk was prepared by mixing the soymilk and commercial homogenized cow milk in the various ratios. Effect of heat treatment, pH and addition of calcium and sucrose was studied on the water-soluble nitrogen of cow-soy milk The heat-treated soymilk at 10$0^{\circ}C$ were centrifuged at the range of 830~29,900xg for 30 min and 11,200xg was found to be proper for determination of the degree of protein denaturation by centrifugal method. When soymilk was heated at 70~10$0^{\circ}C$ for 30~240 min, soluble nitrogen (QA SN) in supernatant of protein was decreased to 78.0~56.8% due to protein denaturation. Most of heat denaturation of protein was found to be occurred during Initial heating 10$0^{\circ}C$ for all mixed cow-soy milk. The sedimentation of SN was maximum at pH 4.0 In the range of pH 3~8. Addition of sucrose affected little on oASN while calcium addition reduced %SN significantly to approx. 55% for soymilk(100%). The effect of Ca was less as the ratio of cow milk increased.

• Korean Journal of Food Science and Technology
• /
• v.28 no.6
• /
• pp.995-1000
• /
• 1996

The present study was attempted to preprare calcium-fortified soymilk using proteases to improve calcium intolerance of soymilk protein and to evaluate its nutritional properties. The protease from Bacillus polymyxa was chosen as an enzyme source because it produced the least bitter taste and calcium-aggregation of soymilk among various enzymes. The optimum treatment time was 10 minutes at $50^{\circ}C$ for the best result. In vitro protein digestibility of calcium-fortified soymilks was comparable with that of control soymilk. Calcium in the digested soymilks was mostly in the ionic form and the amount of ionic calcium increased in accordance with the amount of fortified calcium in soymilk. This suggests that fortified calcium in the soymilk is bioavailable.

• Journal of Dairy Science and Biotechnology
• /
• v.30 no.2
• /
• pp.83-92
• /
• 2012

This study was performed for analyzing the general composition and the change in the quality of soymilk-derived yogurts manufactured by adding skim milk and whey powder to soymilk heat-treated at $95^{\circ}C$/5 min and $120^{\circ}C$/10 min, respectively. 1. During the storage of soymilk yogurt, the concentrations of total solids, protein, fat, and lactose slightly decreased, whereas viscosity, content of ash and NPN, and the number of lactic acid bacteria remained unchanged. 2. The pH and titratable acidity changed rapidly in all soymilk yogurts after 3 h of incubation. 3. We found $7.8{\times}10^8$ lactic acid bacteria in the control sample, $4.7{\times}10^8$ and $5.02{\times}10^8$ in soymilk yogurt with skim milk, respectively, and $5.9{\times}10^8$ and $5.5{\times}10^8$, respectively in soymilk yogurt with whey powder according to degree of heat treatment with $95^{\circ}C$/5 min and $120^{\circ}C$/10 min. 4. The viscosity of yogurt samples became lower as the heat treatment increased in temperature and in the length of time. 5. The value of sensory evaluation was relatively high in soymilk yogurt with the added skim milk, which was heat-treated $95^{\circ}C$/5 min; however, the value was significantly lower than that of the control sample. 6. Lactose, glucose, and galactose were detected in all samples because lactose is degraded into glucose and galactose within 3 h of inoculation.