• Korean Journal of Food Science and Technology
• /
• v.46 no.2
• /
• pp.165-172
• /
• 2014

Mixed fermentation of cow milk was performed by sequential co-cultures with Bacillus subtilis and Lactococcus lactis. After a first fermentation step with B. subtilis for 6 h, the number of viable cells increased to $2.5{\times}10^8$ CFU/mL. The second fermentation step with L. lactis resulted in increased viable cells $1.09{\times}10^{10}$ CFU/mL for 3 days and increased acidity. However, the number of viable B. subtilis cells was decreased greatly to $5{\times}10^1$ CFU/mL following fermentation with L. lactis. Milk proteins were markedly hydrolyzed by the first fermentation after 2 h, and the second fermentation induced curd formation in milk. However, after 4 h, the first fermentation resulted in higher whey separation and 80 mg% tyrosine content. Gamma-aminobutyric acid (GABA) production was dependent upon the degree of protein hydrolysis by first fermentation. Second fermentation resulted in 0.14% GABA. The milk fermented by B. subtilis indicated the rough surface of yogurt depended upon the degree of protein hydrolysis. In conclusion, set-type yogurt was efficiently produced by co-culturing of milk, and fortifying with peptides, GABA, and probiotics.

• Journal of Dairy Science and Biotechnology
• /
• v.32 no.2
• /
• pp.121-129
• /
• 2014

This study was carried out to investigate the quality characteristics of protein enriched fermented milk made with whey and soybean flour. Protein-enriched fermented milk was prepared as follows: Soybean flour was added before fermentation. No synthetic aroma was added. The fermentation starter culture was ABT-4 (Chr. Hansen). Whey protein was added after fermentation. Sensory evaluation indicated that sample containing soybean flour amount of 5% were better than other samples. The pH values and titratable acidities of stored protein-enriched fermented milk and fermented milk, respectively, were not remarkably different. Crude protein was more than 3 times higher in protein-enriched fermented milk (8.77%) than in fermented milk (2.49%). The crude fat content of protein-enriched fermented milk was not remarkably different compared to that of fermented milk. Dietary fiber was more than 2.7 times higher in protein-enriched fermented milk (1.67%) than in fermented milk (0.62%), and the free amino acid content was more than 14 times higher in protein-enriched fermented milk (37.9%) than in fermented milk (2.6%).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.4
• /
• pp.390-397
• /
• 1992

This study was carried out to analyze the physicochemical properties of bovine milks, which were heated with LTLT, HTST, UHT pasteurization and UHT sterilization methods and to compare the heat intensity among the heating methods and samples. The mean HMF values per liter milk were measured as 0.66~1.62 $\mu$M (LTLT), 0.9~1.78$\mu$M (HTST), 3.53$\mu$M(UHT pasteurized) and 7.43~8.97$\mu$M (UHT sterilized) in samples, re- sportively. The available Iysine contents per 100ml milk showed 293.2 mg (Raw), 289.2~291.2 mg (LTLT), 298.4~292.4mg (HTST), 272.4~261.6mg (UHT pasteurized) and 279.0mg (UHT sterilized), respectively. The rates of whey protein denaturation were 9.5~11.4% (LTLT), 9.5~17.1% (HTST), 89.3~95% (UHT pas-tsterilized) and 62.7% (UHT sterilized), respectively. The contents of SH groups per g protein were determined as 2.86$\mu$M (Raw) and 2.95~3.15$\mu$M (LTLT), 3.08~3.18$\mu$M (HTST), 3.26~3.42$\mu$M (UHT Pasteurized) and 3. 36$\mu$M (UHT sterilized), respectively, The SS groups Contents per g protein were 28.93$\mu$M (Raw), 25.72~26. 51 $\mu$M (LTLT), 26.93~26.79$\mu$M (HTST), 23.65~23.04 $\mu$M (UHT pasteurized) and 24.69$\mu$M (UHT sterilized), respectively. The ascorbic acid contents per liter milk were measured 6.05mg (Raw), 1.47~1.65mg (LTLT), 2.50~3.85mg (HTST), 2.87~3.69mg (UHT pasteurized) and 4.50mg (UHT sterilized). The changes of some in-dices in milk samples depend on the heating temperature and time ; the HMF values, SH groups, whey protein denaturation rates increased, while the available lysine contents and SS groups decreased in LTLT, HTST, UHT pasteurized and UHT sterilized milks. No remarkable differences were found in heating indicators between LTLT and UHT milks.

• Food Science of Animal Resources
• /
• v.23 no.1
• /
• pp.63-69
• /
• 2003

This experiment was carried out to study changes in solubility and emulsifying properties of whey protein. Whey protein hydrolysates were obtained from tryptic hydrolysis of whey protein concentrate at pH 8.0 and 37$^{\circ}C$ for 6 hours. Emulsifying activity of whey protein hydrolysate was highest at 4 hours of hydroysis and at 5.50% of DH. During hydrolysis of whey protein concentrate with trypsin, ${\alpha}$-lactalbumin was not easily broken down. But ${\beta}$-lactoglobulin was hydrolysed rapidly from the early stage of hydrolysis, producing several low molecular weight peptides, which have to participate in increasing emusifying activity. The solulbility of hydyolysates tended to increase depending on hydrolysis time; however, there was a gradual decrease after 5 hours. The hydrolysate had a minimum solubility near the isoelectric point range (pH 4∼5). The more hydrolysed the whey protein concentrates, the more soluble they are near the pl. They aye also more soluble above pH 6. Emulsifying activity of hydrolysates showed similar results to solubility. Creaming stability gradually increased when hydrolysis increased, increasing rapidly above pH 8 after 4 hours of hydrolysis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.10
• /
• pp.551-558
• /
• 2017

To study and validate tissue-specific promoters and vectors, it is important to develop cell culture systems that retain the tissue and species specificity. Such systems are attractive alternatives to transgenic animal models. This study established a line of porcine mammary gland epithelial cells (PMECs) from a primary culture based on the cellular morphology and mRNA levels of porcine beta-casein (CSN2). The selected PMECs were stained with the cytokeratin antibody, and were shown to express milk protein genes (CSN2, lactoferrin, and whey acidic protein). In addition, to confirm the acini structure of PMEC932-7 in 3D culture, live cells were stained with SYTO-13 dye, which binds to nucleic acid. The acini of these PMECs on matrigel were formed by the aggregation of peripheral cells and featured a hollow lumens. The system was demonstrated by testing the effects of the culture conditions to cell culture including cell density and matrigel methods of the PMECs. These results suggest that PMECs possess the genetic and structural features of mammary epithelial cells.

• Food Science of Animal Resources
• /
• v.20 no.2
• /
• pp.159-165
• /
• 2000

Glycomacropeptide(GMP) was purified from cheese whey which is obtaining as a byproduct in cheese producing. Cheese whey was first concentrated 10 times with a ultrafiltration aparratus, and then heated at 95$^{\circ}C$ for 5 min. The concentrated fraction was centrifuged at 20,000$\times$g for 30 min to remove fat layer. The supernatant layer enriched GMP protein was fractionated by ion exchange chromatography on DEAE-Sepharose Fast Flow column. GMP was bound to DEAE resin and eluted with 0.1~0.25 M NaCl when using a linear NaCl gradient from 0 M to 0.5 M. The purified GMP gave a single band of 24 kDa which seems to be trimer molecular weight in SDS-PAGE, and migrated to the same molecular weight with control GMP obtained commercially. Its amino acid composition were consistent with that of standard GMP. About 0.71 g of GMP was recovered from 1 L of cheese whey. These results indicate that glycomacropeptide could be simply purified from cheese whey by using ultrafiltration and DEAE column chromatography.

• Korean Journal of Food Science and Technology
• /
• v.39 no.1
• /
• pp.50-54
• /
• 2007

In this study, the physicochemical properties of cheese whey protein isolate (WPI) were measured. The total amount of amino acids in WPI was 89.5% and the proportion of essential amino acids was 44.6%. Among these, leucine, lysine, isoleucine, and valine were shown in large amounts. At various pHs, the solubility of WPI (82-88%) was higher than that of sodium caseinate, (5-79%). The solubility of WPI was not affected by variation of pH. It was shown that the emulsifying capacity of WPI was higher than that of egg yolk by 1.6 times, but the stabilities of emulsions made with WPI and egg yolk was almost same each other at 65-97% and 60-89%, respectively. The foaming capacity of WPI was higher than that of egg white, at 323.3% and 186.6%, respectively, but the foam stability of WPI was similar to that of egg white.

• 한국유가공학회:학술대회논문집
• /
• 2005.06a
• /
• pp.37-61
• /
• 2005

Microcapsules consisting of natural, biodegradable polymers for controlled and/or sustained core release applications are needed. Physicochemical properties of whey proteins suggest that they may be suitable wall materials in developing such microcapsules. The objectives of the research were to develop water-insoluble, whey protein-based microcapsules containing a model water-soluble drug using a chemical cross-linking agent, glutaraldehyde, and to investigate core release from these capsules at simulated physiological conditions. A model water soluble drug, theophylline, was suspended in whey protein isolate (WPI) solution. The suspension was dispersed in a mixture of dichloromethane and hexane containing 1% biomedical polyurethane. Protein matrices were cross-linked with 7.5-30 ml of glutaraldehyde-saturated toluene (GAST) for 1-3 hr. Microcapsules were harvested, washed, dried and analyzed for core retention, microstructure, and core release in enzyme-free simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) at 37$^{\circ}C$, A method consisting of double emulsification and heat gelation was also developed to prepare water-insoluble, whey protein-based microcapsules containing anhydrous milkfat (AMF) as a model apolar core. AMF was emulsified into WPI solution (15-30%, pH 4.5-7.2) at a proportion of 25-50% (w/w, on dry basis). The oil-in-water emulsion was then added and dispersed into corn oil (50 $^{\circ}C$)to form an O/W/O double emulsion and then heated at 85$^{\circ}C$ for 20 min for gelation of whey protein wall matrix. Effects of emulsion composition and pH on core retention, microstructure, and water-solubility of microcapsules were determined. Overall results suggest that whey proteins can be used in developing microcapsules for controlled and sustained core release applications.

• Journal of Animal Science and Technology
• /
• v.48 no.5
• /
• pp.719-726
• /
• 2006

Bovine whey protein are rich in cysteine, which is the rate limiting amino acid for synthesis of antioxidant glutathione(GSH). Some strains of Lactobacillus caseihas been reported to contain high level of GSH in cell extracts. The objective ofthis study was to determine whether enzymatically hydrolyzed whey protein isolate(WPI) and cell extract of Lb. casei HY2782 could increase intracellular GSH concentrations and protect against oxidant induced cell death in human prostate epithelial cell line (designated as RWPE1, and PC3MMM2 cells). Treatment of RWPE1 cellsandPC3MMM2 cells with hydrolyzed WPI (500g/ml) significantly increased GSH by28.2% and38.4% respectively. Compared with control cells receiving no hydrolyzed WPI(P<0.05). hydrolyzed WPI and Lb casei HY2782 cell extracts significantly protected RWPE1 and PC3MMM2 cellsfrom oxidant induced cell death compared with controls receiving no WPI. DNA damage associated with oxidant treatment was demonstrated by single cell gel (SCG) electrophoresis.

• Korean Journal of Food Science and Technology
• /
• v.29 no.5
• /
• pp.947-954
• /
• 1997

Selected physical properties of cornmeal extrudates fortified with dairy products and extrusion process by $CO_2$ gas injection were analysed. Dairy products including whole milk powder, whey protein concentrate non-fat dry milk, and sodium caseinate were tested at the addition of 10% and 20%, based on cornmeal weight. $CO_2$ gas was injected to the barrel at the pressure of 0.7 and 1.4 MPa. Specific mechanical energy (SME) input was decreased by the addition of dairy products. Sodium caseinate had a little effect on decreasing the SME input, however whole milk powder tremendously reduced SME input when the concentration increased. An increase in milk product content resulted in increasing the piece density at the injection pressure of 0.7 MPa. At both 10% and 20% milk product content, the piece density was lowest at the injection pressure of 0.7 MPa. The sectional expansion index was highest at the injection pressure of 0.7 MPa. However, the specific length was constantly increased with the increase in $CO_2$ injection pressure. Water absorption index was decreased and water solubility index was increased by the addition of milk products. The injection pressure of $CO_2$ was optimum at 0.7 MPa. The addition of whole milk powder limited to puff the melt, but the other milk products tested resulted in puffing with $CO_2$ injection to 1.4 MPa.