• Journal of Nutrition and Health
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• 제36권6호
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• pp.549-558
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• 2003

The purpose of this study was to determine which differences in the source of protein (soy vs casein) and isoflavones in soy protein are responsible for the differential effects of bone marks and hormones in growing female rats. Forty-two 21-day-old Sprague-Dawley female rats were randomly assigned to one of three groups, consuming casein (control group), soy protein isolate (57 mg isoflavones/100 g diet), or soy protein concentrate (about 1.2 mg isoflavones/100 g diet). All rats were fed on experimental diet and deionized water ad libitum for 9 weeks. Bone formation was measured by serum osteocalcin and alkaline phosphatase (ALP) concentrations. And bone resorption rate was measured by deoxypyridinoline (DPD) crosslinks immunoassay and corrected for creatinine. Serum osteocalcin, growth hormone, estrogen and calcitonin were analyzed using radioimmunoassay kits. Diet did not affect weight gain and mean food intake. Food efficiency ratio was lower in the soy protein groups. The soy isolate group had a higher ALP and osteocalcin concentration and lower crosslinks value than the casein group. Therefore, the soy isolate groups had a higher bone formation/resorption ratio than the casein group. And, the soy group had significantly higher growth hormone than the casein group. The findings of this study suggest that soy protein and isoflavones are beneficial for bone formation in growing female rats. Therefore, exposure to these soy protein and isoflavones early in life may have benefits for osteoporosis prevention.

• Journal of Nutrition and Health
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• 제29권10호
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• pp.1072-1079
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• 1996

This study was performed to elucidate the mechanism of dietary protein level on renal function through lipid and eicosanoids metabolism. Male rats of 337.8$\pm$5.7g body weight were undergone unilateral nephrectomy or sham-operation. The rats were divided into high protein(40% casein), normal protein(15% casein) and low protein(8% casein) diet groups and fed experimental diets ad libitum for 24 weeks. The results are summarized as follows. Serum total lipid, cholesterol and HDL-cholesterol of rats in 15% and 40% casein groups were higher than those of 8% casein group. But serum triglyceride was affected neither by uninephrectomy nor by dietary protein level. Serum thromboxane(TX) B2 and 6-keto prostaglandin F1$\alpha$ increased with increasing dietary protein level. Serum prostaglandin(PG) E2 was not affected by uninephrectomy nor by dietary protein level. Urinary PGE2 and TXB2 excretion tended to be lower in uninephrectomized groups. Renal tissue concentration of TXB2 was lower in uninephrectomized groups and in high protein group. These results suggest the possibility that the effects of dietary protein level on renal function could be due to changes in lipid and eicosanoids metabolism.

• 한국축산식품학회지
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• 제30권4호
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• pp.545-550
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• 2010

The effects of casein hydrolysate on blood pressure (BP) and serum lipid profiles were investigated in spontaneously hypertensive rats (SHR). Twenty-four 6-wk old male SHRs were assigned to 3 groups in a completely randomized design. Experimental groups were as follow: control, market milk group (MLG) and casein hydrolysate group (CHG). Reference blood pressure (RBP) showed average $198.94{\pm}1.46mmHg$. Blood pressure (BP) of CHG reduced 24 mmHg after 2 wk of treatment, but these increased after 3 wk. BP of CHG was significantly lower than BP of Control in experimental time (p<0.05). Serum lipid profiles were not differ significantly among groups (p<0.05). These data suggest that casein hydrolysate may beneficially improvement of blood pressure level in SHR.

• Journal of Nutrition and Health
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• 제40권3호
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• pp.229-234
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• 2007

This study was conducted to investigate the effect of different kinds of traditional Korean soybeans on blood and liver lipids and lipid peroxidation. SD male rats (n=48) were assigned to six different groups and provided experimental diets for 28 days. The protein source of the diet was casein, isolated soy protein (ISP), or casein plus traditional soy powders (yellow bean, huktae, jinuni or seorietae). The ISP, jinuni and seorietae diet decreased blood triglyceride compared to casein group. The ISP groups had lower hepatic total lipid and triglycerides than casein groups. The yellow bean and seorietae group had hepatic lipid lowering effects, but the effect was not found in huktae and jinuni group. The glutamate-oxaloacetate transaminase activity was significantly decreased in ISP and jinuni groups than in casein group. The glutamate-pyruvate transaminase activity was also decreased in ISP group. The results of this study suggest that jinuni, yellow bean and seorietae groups are more effective in lowering body lipids than huktae group.

• 한국식품조리과학회지
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• 제7권4호
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• pp.93-101
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• 1991

The object of this study was to investigate characteristics of kiwifruit protesae and effect of this enzyme on the functionality of casein. The specific activity of crudely prepared kiwifruit pretense on casein was 196.95 units/mg protein, it showed optimum activity at pH 3.0, $60^{\circ}C$. The degree of hydrolysis of casein with pretense treatment steeply increased to 73.5% and 78.9% for 10 and 20 minutes and then reached 84.1% and 89.3% for 1 and 4 hours, respectively. Solubility of non heated control group was 0.2% at pH 4, while the sample groups treated with enzyme for 0, 10 and 20 minutes were 14.5%, 19.2% and 24.0%, respectively. Casein treated with pretense showed marked increase in foam expansion near isoelectric point. However, enzymatically treated groups had lower foam expansion than the control groups. Foam stabilities of enzymatically modified group were lower than those of the control groups at all pH. Emulsifying activity of the non-heated control group was 0% at pH 4, while the groups modified enzymatically for 0, 10, and 60 minutes showed 51.0%, 55.5% and 54.5%, respectively.

• 한국식품과학회지
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• 제30권5호
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• pp.1035-1039
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• 1998

수용액상에서 단백질과 다당류 사이의 비혼합성은 일반적인 현상이므로 다양한 조성과 형태의 수용성 거대분자를 포함하는 식품에서 상분리는 매우 전형적인 현상이다. 본 연구에서는 식품원료로 자주 쓰이는 카제인과 알긴산을 이용하여, pH (6, 8, 10), NaCl 농도(0, 0.25, 0.5 M), 알긴산의 분자량$(1.64{\times}10^5,\;1.95{\times}10^5)$에 따른 상분리현상에 대하여 연구하였다. 식품에서 카제인이 유화제로 작용할 때 알긴산의 첨가에 따른 혼합성의 변화는 카제인의 유화안정성에 영향을 끼치게 된다. 알긴산의 분자량에 따른 혼합성의 차이는 크게 나타나지 않았다. pH가 높을수록, 염농도가 낮을수록 카제인-알긴산 혼합물의 비혼합성은 감소하였다. 이 결과로 보아 카제인과 알긴산 사이의 정전기적 작용이 혼합성에 관련되어 있는 것으로 생각된다.

• 대한가정학회지
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• 제30권4호
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• pp.89-105
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• 1992

The purpose of this study was to see the effect of oral administration of reserpine (2mg/d) and tryptophan (40.35mg/d) on the serum amino acid concentrations and organ composition, food consumption, body weight, blood hematocrit(Hct) and hemoglobin(Hb) levels in Sprague-Dawley rats fed 6% or 20% casein diet. Any adverse effects of reserpine and tryptophan were not observed in animals, except that liver fat contents were increased in low protein group. In other words the administration of typtophan decreased liver fat contents in 6% casein and reserpine-treated 20% casein groups, but increased in reserpine-treated 6% casein group. But the low protein diet had significant adverse effects in animals. The 6% casein diet, therefore, had a tendency to decrease food consumption and body weight. The simillar tendency was shown in serum essential amino acid concentrations, organ weight and protein contents of liver and muscle. From the results, it would be safe to conclude that the oral administration of large deses of reserpine and tryptophan did not induce such a signifcant malnutrition as the low protein diet did.

• Nutrition Research and Practice
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• 제11권4호
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• pp.281-289
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• 2017

BACKGROUND/OBJECTIVE: The incidence of colorectal cancer (CRC) has been attributed to higher intake of fat and protein. However, reports on the relationship between protein intake and CRC are inconsistent, possibly due to the complexity of diet composition. In this study, we addressed a question whether alteration of protein intake is independently associated with colonic inflammation and colon carcinogenesis. MATERIALS/METHODS: Balb/c mice were randomly divided into 4 experimental groups: 20% protein (control, 20P, 20% casein/kg diet), 10% protein (10P, 10% casein/kg diet), 30% protein (30P, 30% casein/kg diet), and 50% protein (50P, 50% casein/kg diet) diet groups and were subjected to azoxymethane-dextran sodium sulfate induced colon carcinogenesis. RESULTS: As the protein content of the diet increased, clinical signs of colitis including loss of body weight, rectal bleeding, change in stool consistency, and shortening of the colon were worsened. This was associated with a significant decrease in the survival rate of the mice, an increase in proinflammatory protein expression in the colon, and an increase in mucosal cell proliferation. Further, colon tumor multiplicity was dramatically increased in the 30P (318%) and 50P (438%) groups compared with the control (20P) group. CONCLUSIONS: These results suggest that a high protein diet stimulates colon tumor formation by increasing colonic inflammation and proliferation.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2006년도 정기총회 및 제37차 춘계 국제학술발표대회
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• pp.250-252
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• 2006

Casein을 인공 소화관 내의 조건으로 처리한 가수분해물의 ACE 저해활성 측정 및 이를 유제품에 적용하기 위한 기초자료 수집을 위해 관능검사를 실시하였다. Casein을 인공위액과 인공장액으로 각각 단독으로 처리했을 때의 ACE 저해 활성보다는 인공 위액과 인공 장액의 연속처리를 받은 가수분해 분해물의 ACE저해 활성이 더 높게 나타났다. 또한 가수분해물의 관능검사를 실시한 결과에서는 백색 시유에는 0.3% 정도의 첨가가 적당하였으며, 초코우유나 커피우유에 첨가할 경우에는 0.5% 정도까지 첨가하여도 맛에 크게 변화를 주지 않았다.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1031-1035
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• 2004

The adsorption kinetics of ${\beta}$-casein on a hydrophobic surface has been studied by means of the quartz crystal microbalance (QCM). The self assembled monolayer of 1-octadecanethiol on a gold coated quartz crystal was used as a hydrophobic surface for adsorption. The adsorption kinetics was monitored in different solution conditions. Formation of monolayer is observed in most cases. At high concentration of protein, micelle formation which is interrupted by high ionic strength of solution is observed. Casein binding cations such as $Ca^{2+},\;Ba^{2+}\;and\;Al^{3+}$ increase the hydrophobicity of the protein and the multiple layer adsorption occurs. The strong and weak points of the QCM method in the study of protein adsorption are discussed.