• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2001.12a
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• pp.61-68
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• 2001

Soybean, rice and nuts are the staple foods in South East Asia. In order to clarify the function of these foods in relation to coronary heart diseases, we have done a series of experiments using animals and humans. Soybean protein preparations (SPI) in comparison with an animal protein, casein (CAS), resulted in reducing atherosclerotic lesion development in apolipoprotein (apo) E deficient mice that develop an advanced lesion similar to that in humans. This action was attributed to the protein, since the ethanol-extracted SPI (EE-SPI), from which isoflavones and saponins removed, lowered the lesion development in apo E-deficient mice. However, The EE-SPI, compared to the SPI, resulted in a decrease of mRNA for key proteins of cholesterol metabolism (low density lipoprotein receptor and cholesterol 7$\alpha$-hydroxylase) in hypercholesterolemic rats, followed by an elevation of the serum cholesterol level, indicating a contribution of isoflavones to the serum cholesterol level. Rice protein (RPI) was also effective to lower the lesion development in apo E deficient mice. Both the SPI and RPI led to an increased level of the serum NOiN03, metabolites of NO. This effect appeared to be attributed to their high content of arginine. Besides, C57BL/6J mice fed a diet containing whole grain rice had an elevation of the serum high-density lipoprotein cholesterol. Furthermore, rice bran oil and the unsaponifiable fraction that is rich in plant sterols were effective to lower serum cholesterol levels in hypercholeserolemic rats. Finally, we tested if walnuts consumption would be hypocholesterolemic for Japanese. A diet containing walnuts effectively lowered the serum total and low density lipoprotein cholesterol in Japanese men and women. These animal and human experiments would be relevant to advocate publics to keep consuming diets including soybean, rice and nuts for their healthful life.

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.554-558
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• 2010

In the study, the protease activity of kiwifruit (Actinidia deliciosa Planch) cultivated in Korea was estimated, with specific examination of proteolytic effects on myofibrilar protein. The crude protease extract of kiwifruit was prepared in two ways; one in which the kiwifruit was homogenized with buffer followed by centrifugation, and the other were the supernatant was precipitated by saturated ammonium sulfate followed by dialysis. The former had 21.23 mM/mL of protease activity, which corresponded to 112.28 mM/g kiwifruit utilized, and the latter had 11.58 mM/mL and 45.80 mM/g of kiwifruit. The crude protease extract of the kiwifruit showed high specificity for casein substrate followed by bovine serum albumin, egg white, collagen, and elastin, in order. The enzyme lost proteolytic activity in acidic conditions such as pH 2-3, and at high temperatures over $60^{\circ}C$. It showed optimal activity in both pH 3.0 and pH 7.5 as well as at $40^{\circ}C$ for casein substrate and at $50^{\circ}C$ for myofibrilar protein substrate. The proteolytic activity toward casein was high with up to 0.5M salt, followed by a sharp decrease beyond this concentration. On the other hand the proteolytic activity for myofibrilar protein decreased steadily with increasing of salt concentration. Kiwifruit has been used as a for meat tenderizer for in home cooking and these results support the its tenderizing effectiveness of kiwifruit especially for Korean style marinating of meat for cooking.

• KSBB Journal
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• v.9 no.5
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• pp.483-491
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• 1994

It is known that a key limiting factor to the use of ultrafiltration membranes is that of membrane fouling, which has been a major cause of permeate flux reduction. In this work, the effects of several factors (operating time, protein concentration, temperature and pH, etc.) influencing permeate flux during ultrafiltration of gelatin, casein and bovine serum albumin using a hollow fiber membrane(M. W. 10,000 cut off) reactor have been examined. The permeate flux of gelatin solution was maintained almost constant during the operation up to 6 hours, but those of casein and albumin solutions were decreased to 50% and 43% of initial value after an operation time of 60min. The permeate flux with increasing concentration and temperature of protein solutions increased, but the permeate flux showed a minimum value near the isoelectric point of proteins. The permeate fluxes of protein solution were enhanced by a temperature increase and pH control. Also, it is proposed that fouling can be decreased by the pretreatment of insoluble proteins with enzymes.

• Journal of Nutrition and Health
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• v.34 no.8
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• pp.843-849
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• 2001

This study was performed to investigate the effect of n-3 fatty acids and dietary protein levels on renal function. Fifteen-month old male Sprague-Dawley rats were divided into 4 diet groups. Two-month old rats were used as a control group. The experimental diets contained either a% or 25% casein and lipid levels of the diets were 20% by weight. For the control group, the lipid was composed of beef tallow and corn oil on a 1:1 basis, and fish oil was comprised 75% of the fat mixture for the fish oil group. Rats were fed the diets ad libitum for 8 weeks. GFR and urinary protein excretion were higher in high protein groups, while fish oil exhibited no effects. Renal medulla TXB$_2$and PGE$_2$ concentrations tended to be higher in high protein groups and lower in fish oil groups. Light microscopic examinations showed that glomerulosclerosis, tubular atrophy, tubular cast, interstitial inflammation and interstitial fibrosis fended to be higher in aged rats and in high protein groups and lower in fish oil groups. Serum levels of total lipid, triglyceride and total cholesterol were higher in aged rats and lower in fish oil groups while serum HDL-cholesterol level was higher in young rats and in fish oil groups. However, dietary protein level had no effect on serum lipid levels. Serum TBARS concentration was higher in aged rats and in fish oil groups. In conclusion, fish oil caused changes in serum lipid concentrations and eicosanoids metabolism. The effect of fish oil on renal function was less obvious than dietary protein. However, fish oil seemed to be effective in lessening deterioration of renal function due to aging and/or high protein diets through changes in lipid and eicosanoids metabolism.

• Journal of Animal Science and Technology
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• v.48 no.5
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• pp.671-682
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• 2006

This experiment was conducted to investigate the effects of dietary Ca levels and some feed additives such as isoflavone and casein phosphopeptide (CPP) on eggshell quality and hatching egg production in aged egg-type breeder hens. A total of three hundred and sixty, 56-week-old Hy-Line Brown breeder hens were divided into six groups and fed experimental diets of two levels of Ca (3.3% or 3.6%) either with addition of 0.2% isoflavone, 0.5% CPP or devoid of all for 5 weeks. There were no significant differences in laying performances and settable egg production among the groups. Significant increases (P<0.05) in eggshell strength were observed with increasing dietary Ca and addition of isoflavone, but not with addition of CPP. Fertility and hatchability were not influenced by dietary Ca and addition of isoflavone or CPP. The treatment had few significant effects on tibial proximal compositions and breaking strength. The concentrations of Ca, P, estrogen and calcitonin in serum were not affected by the dietary treatments. These results indicated that relatively high level of dietary Ca in combination with isoflavone had a beneficial effect on improving eggshell quality in aged egg-type breeder hens. But hatching egg production was not affected by dietary isoflavone or CPP.

• Journal of the Korean Applied Science and Technology
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• v.6 no.2
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• pp.89-104
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• 1989

The purpose of the study was to find an effect of phospholipid-free vegetable oils on the serum lipids and proteins of Sprague-Dawley rats. All experimental rats were fed ad libitum for 60days with the mixture of starch: casein: salt mixture: vitamin mixture (60:18:4:1) and at the same time fed administratively with 1 ml of soybean oil, corn oil and sesame oil bought in market as source of phospholipid-free vegetable oils(PFVO) and those extracted directly by and oil press as source of phospholipid-containing vegetable oils(PCVO) respectively. At the last day of experimental period, the rats were fasted for 12 hours and decaptitated to collect blood for analysis of serum lipid and protein. The results of this study were summerized as follows. 1. The supplementation of dietary phospholipid decrease food efficiency ratio and the growth rate of experimental rats. 2. The supplementation of dietary phospholipid improve correlation coefficient of body weight and organ weights. 3. The supplementation of dietary phospholipid increase the level of serum phosphatidylethanolamine. Therefore, I think that we must eat dietary phospholipid unpurified from vegetable oil to prevent development of atherosclerosis and fat liver.

• Journal of Nutrition and Health
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• v.5 no.4
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• pp.169-176
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• 1972

The present study was undertaken to determine the metabolic effect of various levels of fat in the diet. Forty males and the same number of females weighing $35{\pm}29$ were divided into three experimental groups and one control group, 10 rats each in both sexes. The dietary lipid contents were included in three levels, 2% as low, 30% as high and fat free diet in order to reflect the lipid consumption of present Korean diet. 20% sugar casein diet were employed as standard for control animals. This study was carried for 16 weeks. After these period animals were sacrificed to collect the internal organs and blood samples by heart puncture. In the result of this study, high fat diet group is lower than low fat diet group in the body weight gain, food efficiency ratio, protein efficiency ratio, urinary nitrogen and organ nitrogen contents were same trend but there is no significant difference in these respects. It was noteworty that high, and free fat diet group revealed more glucose total protein, albumin and globulin contents in the serum than other compared groups. It can be concluded that fat content whether low or high are free in the diet did not show significant effect on body nitrogen metabolism. But 30% high fat diet increased the total lipid and total cholesterol contents in the liver and the serum. This fact can be interpreted that 2% low fat diet and fat free diet do not need to increase the amount of fat content in the diet as high as 30% fat diet. This result might indicate the one possible reason to decide the recommanded dietary fat levels in Korean diet.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.119-126
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• 1986

A periplasmic endoprotease, named protease Pi, was purified to homogeneity from Escherkchia coli by conventional procedure with insulin as substrate. This enzyme degrades insulin and glucagon to trichloroacetic acid-soluble meterials, but shows little or no hydrolysis of bovine serum albumin, casein or globin. Its molecular weight was 110, 000 when determined by gel filtration on Sephacryl S-300 and was 105, 000 when estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Thus, it appears to be single polypeptide. This snzyme is metalloprotease, since it is completely inhibited by o-phenanthroline and can be activated by addition of divalent metal cations, such as $Mg^{2+}\;and\;Co^{2+}$. It is destinct from protease Ci, a cytoplasmic insulin degrading enzyme, since protease Pi is localized to the periplasm. Since protease Pi selectively degrades GTP cyclohydrolase I, it appears to play a role in the regulation of pteridine biosynthesis.

• Journal of Nutrition and Health
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• v.24 no.1
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• pp.20-29
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• 1991

This study was carried out to compare the protein quality of lamb and beef meat. by feeding to growing rats. Sixty weanling rats, 30 males and 30 females, were blocked into 12 groups(6 gruops of males and 6 groups of females). They were fed casein. beef, or lamb as a protein source at two levels, 6 and 15%, for 5 weeks. The amount of food intake. food efficiency ratio, protein efficiency ratio. body weight gain. and the weights of skeletal muscles and liver were measured. Nitrogen retention, protein content in the liver and skeletal muscles, and the levels of protein and cholesterol in the serum were also assayed. Summarzing the results, there were no significant differences between lamb and beef on the growth and nitrogen utilization in the rats fed same percentage of protein diet. However. rats fed 15% protein diet showed significantly higher growth rate than those fed 6%. Therefore, it can be concluded that lamb is as good a protein food as beef in terms of protein quality.

• Journal of Nutrition and Health
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• v.28 no.2
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• pp.144-151
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• 1995

This study investigates the supplementing effects of milks by various heat treatment on growth performance and protein and calcium metabolism of rats. For 4 weeks, raw, LTLT-HTST-and UHT-processed milks were given to rats which fed on a calcium free, semi-synthetic diet containing 5%casein. There were no significant differences among the experimental groups in weight gain, feed efficiency ratio and the serum level of total protein and calcium. Also, no significant differences were showed in protein efficiency, nitrogen balance, apparent protein digestibiltiy and the contents of weight and calcium of the left femur as well as 2 incisors. However, the biological value of protein in the UHT-milk group was significantly higher than that of the raw-milk group. The apparent calcium digestibility and calcium balance in the UHT-milk group were higher than those in the raw-, LTLT- and HTST-milk groups. The weight of left femur in all the groups supplemented with various heat-treated milks was significantly impair the nutritive value of protein and calcium in milk. Futhermore, UHT-processing may improve the bioavailability of protein and calcium in milk.