• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.72-73
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• 1994

Whey는 일명 lactoserum 이라고도 하며 치즈제조시 우유를 응고시키는 과정에서 Casein과 지방으로부터 분리되어 나오는 액상의 부산물로 본래 우유 부피의 약 90%를 차지하며, 용해성 단백질, 유당, 비타민과 무기질 등을 함유하고 있다. 유청에 함유되어 있는 단백질은 건조고형분의 약 13%가 되는데, 주요 단백질은 $\beta$-lactoglobulin(50%), $\alpha$-lactalbumin(22%), Serum albumin(5%), Immunoglobulin(12%), Proteose-peptone(10%) 등이 있다. 유청단백질중 가장 많이 함유되어 있는 $\beta$-lactoglobulin은 구형의 단백질로 단량체의 분자량은 약 18,400이며, pH 3.5~7 범위내에서는 해리되지 않는 이량체(dimer)를 형성한다. pH 3.5 이하에서 이량체는 해리되고 다량체의 형성으로 재평성한다. pH 7.0 이상의 알칼리 영역에서는 Conformational Change가 일어나는 것으로 알려져 있으며, 등전점(isoelectric point)은 pH 5.2이다. $\alpha$-lactalbumin은 14,200의 분자량을 가지는 구형의 단백질로 등전점은 pH 4.8이다.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.6
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• pp.685-693
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• 1996

A total of 3,610 Ayrshire and 1,711 Jersey cows were phenotyped for the genetic variants of ${\alpha}_{s1}$-casein, ${\beta}$-casein, $\chi$-casein, ${\beta}$-lactoglobulin and ${\alpha}$-lactalbumin. Least squares analyses showed possible associations between milk protein phenotypes and lactational production traits. Depending on lactation number, ${\beta}$-casein phenotypes in Ayrshires were associated with milk production ($A^2A^2$ > $A^1A^2$ > $A^1A^1$), and with milk protein content. In the third lactation, Ayrshire cows with ${\beta}$-casein $A^1A^1$ produced milk with 3.43% fat compared to 3.37% fat for ${\beta}$-casein $A^2A^2$. In Ayrshire, $\chi$-casein phenotypes affected the protein content during the three lactations (BB > AB > AA) and ${\beta}$-lactoglobulin phenotypes significantly influenced the milk fat during the first lactation (4.06% for AA and 3.97% for BB). In Jerseys, protein content of milk was influenced by phenotypes of ${\alpha}_{s1}$-casein(3.98% for CC v/s 3.86% for BB in the first lactation). In the third lactation, $\chi$-casein AA of Jersey milk contained 5.35% fat compared to 4.82% for phenotype BB. The effects of ${\beta}$-lactoglobulin phenotypes on protein content were apparent in Jerseys during the second lactation with the A variant being superior to the B (4.00% for AA v/s 3.87% for BB).

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.7
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• pp.1041-1045
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• 2003

In order to study the reaction behaviors of bovine $\alpha$-lactalbumin ($\alpha$-La), $\beta$-lactoglobulin ($\beta$-Lg), and their mixtures during heat treatment, samples were analyzed using native-polyacrylamide gel electrophoresis (Native-PAGE), sodium dodecylsulfate (SDS)-PAGE, and two-dimensional (2-D)-PAGE. The electrophoresis demonstrated that the loss of native-$\alpha$-La increased as temperature increased, and that the loss of apo-$\alpha$-La was slightly higher than that of holo-$\alpha$-La. The tests also showed that during heat treatment, a mixture of $\alpha$-La and $\beta$-Lg was less stable than $\alpha$-La alone. As such, it was assumed that $\beta$-Lg induced holo-$\alpha$-La to be less stable than apo-$\alpha$-La during heat treatment. The reaction behavior of $\alpha$-La (holo-, apo-form) during heat treatment showed similar patterns in the 2-D-PAGE electropherogram, but the mixture of $\alpha$-La and $\beta$-Lg created new bands. In particular, the results showed a greater loss of native $\alpha$-La in the holo-$\alpha$-La and $\beta$-Lg mixture than in the apo-$\alpha$-La and $\beta$-Lg mixture. Thus, it can be concluded that the holo-$\alpha$-La and $\beta$-Lg mixture was more intensively affected by heat treatment than other samples, and that free sulphydryl groups took part in the heat-induced denaturation.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.3
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• pp.420-427
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• 2015

It is necessary to understand the cellular uptake and cytotoxicity of food-grade delivery systems, such as ${\beta}$-lactoglobulin (${\beta}$-lg) nanoparticles, for the application of bioactive compounds to functional foods. The objectives of this study were to investigate the relationships between the physicochemical properties of ${\beta}$-lg nanoparticles, such as particle size and zeta-potential value, and their cellular uptakes and cytotoxicity in Caco-2 cells. Physicochemical properties of ${\beta}$-lg nanoparticles were evaluated using particle size analyzer. Flow cytometry and confocal laser scanning microscopy were used to investigate cellular uptake and cytotoxicity of ${\beta}$-lg nanoparticles. The ${\beta}$-lg nanoparticles with various particle sizes (98 to 192 nm) and zeta-potential values (-14.8 to -17.6 mV) were successfully formed. A decrease in heating temperature from $70^{\circ}C$ to $60^{\circ}C$ resulted in a decrease in the particle size and an increase in the zeta-potential value of ${\beta}$-lg nanoparticles. Non-cytotoxicity was observed in Caco-2 cells treated with ${\beta}$-lg nanoparticles. There was an increase in cellular uptake of ${\beta}$-lg nanoparticles with a decrease in particle size and an increase in zeta-potential value. Cellular uptake ${\beta}$-lg nanoparticles was negatively correlated with particle size and positively correlated with zeta-potential value. Therefore, these results suggest that the particle size and zeta-potential value of ${\beta}$-lg nanoparticles play an important role in the cellular uptake. The ${\beta}$-lg nanoparticles can be used as a delivery system in foods due to its high cellular uptake and non-cytotoxicity.

• Development and Reproduction
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• v.4 no.2
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• pp.221-229
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• 2000

Lactogenesis in mammary gland is under the control of various lactogenic hormones including hypophysial growth hormone and prolactin. Recent studies reported that such pituitary lactogenic hormones are also expressed in mammary cells as well as in pituitary. For the purpose to analyze the role of these non-pituitary hormones in mammary cells, $\beta$ -lactoglobulin (BLG) gene promoter was selected as a model system. The growth hormone suppressed BLG promoter activity when it was applied alone on cultured mammary HCll cells. Along with lactogenic hormones such as insulin, prolactin and glucocorticoid, however, it significantly enhanced expression of BLG promoter activity in a dosage- dependent manner. Exogenous expression of the growth hormone gene in cultured mammary cells also strongly promoted cell proliferation and BLG promoter activity. Bovine growth hormone promoter, on the contrary, did not revealed any notable activity. Above results suggest that endogenous expression of the pituitary hormone genes in mammary cells is not a regulation leakage but a physiological control. Moreover, artificial overproduction of the growth hormone in mammary gland may help increase milk production.

• Food Science of Animal Resources
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• v.24 no.2
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• pp.182-188
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• 2004

To determine the concentration of Lactoperoxidase (LPO), an indirect enzyme-linked immunosorbant assay(ELISA) was developed. Anti-LPO egg yolk immunoglobulin(IgY) was transferred to egg yolk by immunizing of Brown hens with LPO. The titer of purified anti-LPO IgY was 1: 520,000. The immunological response of anti- LPO IgY with ${\alpha}$-lactalbumin, ${\beta}$-lactoglobulin, casein and lysozyme were evaluated, resulting that the anti-LPO IgY found to be a specific antibody toward LPO and no cross-reaction was observed against ${\alpha}$-lactalbumin, ${\beta}$-lactoglobulin, casein, and lysozyme in double immunodiffusion test and ELISA test. In indirect ELISA method, coating concentration of LPO and dilution rate of anti-LPO IgY was 0.25$\mu\textrm{g}$/mL and 1:8,000 respectively. Sensitivity in the standard curve of LPO was ranged from 0.01 to 1$\mu\textrm{g}$/mL using anti-LPO IgY.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.2
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• pp.187-194
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• 1995

Genetic variants of ${\alpha}s_1$-casein, ${\beta}$-casein, ${\kappa}$-casein and ${\beta}$-lactoglobulin were investigated by starch urea gel electrophoresis in milk samples of 280 Korean native cattle. A new ${\beta}$-casein variant, designated ${\beta}$-casein $A^4$, was found in milk samples of Korean native cattle. It has a much slower electrophoretic mobility than the ${\beta}$-casein $A^3$ variant in acid gel. This new variant appeared together with either ${\beta}$-casein $A^1$, $A^2$ or B variant. Gene frequencies and genotypic frequencies were estimated. Gene frequencies of four milk protein loci in Korean native cattle were compared with those of imported cattle breeds raised in Korea and Japanese brown cattle. Gene frequencies were ${\alpha}s_1$-casein B .846, ${\alpha}s_1$-casein C .154; ${\beta}$-casein $A^1$ .216, ${\beta}$-casein $A^2$ .666, ${\beta}$-casein $A^4$ .048, ${\beta}$-casein B .070; ${\kappa}$-casein A .648, ${\kappa}$-casein B .352; ${\beta}$-lactoglobulin A .148, ${\beta}$-lactoglobulin B .852. The population was in Hardy-Weinberg equilibrium at all milk protein loci. Gene frequencies of Korean native cattle were very similar to those of Japanese brown cattle. Interestingly, a new variant, ${\beta}$-casein $A^4$, was found only in Korean native cattle and Japanese brown cattle. These results support the hypothesis that Korean native cattle were used in the development of the Japanese brown cattle.

• Journal of the Korean Applied Science and Technology
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• v.17 no.3
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• pp.158-166
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• 2000

A conductimetric study of foam formed from mixture of the protein, ${\beta}-lactoglobulin$, and the nonioinc surfactant, SML, revealed that their stability was reduced at concentrations of SML in the range $3{\sim}10mM$. The interaction of SML with ${\beta}-lactoglobulin$ was investigated by fluorimetry and a dissociation constant of $0.2{\mu}M$ was calculated for the complex. Surface tension studies confirmed the presence of interaction between the two components and provided evidence for the progressive displacement of ${\beta}-lactogloblin$ from the air/water interface with increasing SML concentration. Experiments using air-suspended microscopic thin liquid films revealed transitions in the chainage characteristics and thickness of the film at SML concentrations below that which resulted in destabilization of the foam. However, measurements of surface mobility of fluorescent-labeled ${\beta}-lactoglobulin$ by a photobleaching method identified that a transition to a mobile system occurred at a SML concentration which correlated with the onset of instability in the disperse phase. The results would indicate that maintenance of the viscoelastic properties of the surface is paramount importance in determining the stability of interfaces comprising mixtures of protein and surfactant.

• Food Science of Animal Resources
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• v.36 no.4
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• pp.516-522
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• 2016

Goat milk is highly nutritious and is consumed in many countries, but the development of functional foods from goat milk has been slow compared to that for other types of milk. The aim of this study was to develop a goat milk protein hydrolysate (GMPH) with enhanced digestibility and better hypoallergenic properties in comparison with other protein sources such as ovalbumin and soy protein. Goat milk protein was digested with four commercial food-grade proteases (separately) under various conditions to achieve the best hydrolysis of α_s -casein and β-lactoglobulin. It was shown that treatment with alcalase (0.4%, 60℃ for 30 min) effectively degraded these two proteins, as determined by SDS-PAGE, measurement of nonprotein nitrogen content, and reverse-phase high-performance liquid chromatography. Hydrolysis with alcalase resulted in a significant decrease in β-lactoglobulin concentration (almost to nil) and a ~40% reduction in the level of α_s-casein. Quantification of histamine and TNF-α released from HMC-1 cells (human mast cell line) showed that the GMPH did not induce an allergic response when compared to the control. Hence, the GMPH may be useful for development of novel foods for infants, the elderly, and convalescent patients, to replace cow milk.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.8
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• pp.1212-1217
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• 2003

Fifty-two Holstein cows with different phenotypes of $\kappa$-casein ($\kappa$-CN) and $\beta$-lactoglobulin ($\beta$-LG) were selected to provide weekly milk samples for heating at 30, 70, 75 and $80^{\circ}C$ for 2 min. Coagulating properties of heated milk samples measured as rennet clotting time, rate of curd firming and curd firmness at cutting were determined by a Formagraph. Milk samples were analysed for fat and casein. Least squares analyses of data, after adjustments were made for effect of milk casein and fat contents, indicated that although an increase in heating temperatures resulted in less desirable coagulating properties, the effect of milk types was inherent irrespective of heating temperatures. The shortest rennet clotting time (6.06 min), fastest rate of curd firming (5.61 min) and firmest curd (38.05 mm) were obtained from milk with the B variant for $\kappa$-CN and B variant for $\beta$ -LG when preheated at $30^{\circ}C$. It appears that milk bearing $\kappa$-CN B is more resistant to heat perturbation. All milk samples having the $\kappa$-casein AA (milk types AA/AA, AA/AB, AA/BB) did not have a measurable K20 value when preheated at $70^{\circ}C$. This effect was observed for $\kappa$-casein AB (milk types AB/AA, AB/AB, AB/BB) at $75^{\circ}C$ and $\kappa$-casein BB (milk types BB/AA, BB/AB, BB/BB) at $80^{\circ}C$.