• Korean journal of food and cookery science
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• v.11 no.1
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• pp.26-32
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• 1995

This study was carried out to investigate the effect of protease on the functionality of soymilk protein. The protease from Bacillus polymyxa was selected because of the least production of bitter taste and calcium-aggregation. The results are summarized as follows: 1. Solubility of SMP(soymilk protein) and SPI(soyprotein isolate) were lowest at pH 4.7 and increased as the pH value reached closer to either ends. PT-SMP(pretense treated soymilk protein) showed higher solubility at all pH range, especially at pH 4.7 than SMP, SPI. 2. Emulsion activity of three samples was lowest at pH 4.7 and significantly increased as pH approched higher acidic or alkaline regions. PT-SMP showed similar activity to other samples, but less stability. 3. Foam capacity of PT-SMP was lowest at pH 8 and increased in acidic, alkaline pH. PT-SMP showed higher foam capacity at all pH range, but lower foam stability than SMP and SPI. 4. PT-SMP showed higher heat coagulability than other samples at all pH range except pH 4.7.

• Korean Journal of Food Science and Technology
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• v.21 no.3
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• pp.338-344
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• 1989

This study was conducted to investigate the mechanism involved with gelation of soybean proteins, 7S and 11S. For the preparations of soybean gels, calsium coagulation and isoelectric point precipitation through the lactic acid fermentation were employed. The textural properties and microstructure of soybean curds were examined by Instron Universal Testing Machine and Scanning Electron Microscope(SEM), respectively. Soybean cheeses were also prepared from soyprotein curds. The characteristics of prepared soybean cheeses were studied by Instron and Sensory evaluation. Microstructure of soybean curds demonstrated by SEM differed markely, postulating that molecular interaction occured in the curds varied with type of protein and coagulative conditions. Textural parameter measured by Instron demonstrated that the curds and the cheeses made through lactic acid fermentation showed higher values in hardness, gumminess and chewiness than those coagulated with $CaCl_2$ 11S PRF could give the curds with higher values in hardness, cohesiveness, springiness, gumminess and chewiness than SPI and 7S PRF Sensory evaluation results showed that soybean cheese made from 11S PRF scored higher values in taste, chewiness, and hardness. However, panels preferred soybean cheese prepared from SPI in color, chewiness and brittleness.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.267-272
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• 1996

Effect of freezing of soybeans on instrumental and sensory textures of soybean curd was investigated. The hardness, gumminess and chewiness of soybean curd prepared with frozen soybeans were about three times as high as those prepared with unfrozen soybeans, while cohesiveness and elasticity were affected little by freezing. Sensory evaluation showed that freezing improved the quality of soybean curd. Instrumental and sensory textures of soybean curd prepared with frozen soybeans were excellent and almost same regardless of the boiling time when the soy slurry was boiled for 2.5 min or 5 min. However, the textures of soybean curd prepared with unfrozen soybeans were deteriorated by reducing the boiling time to 2.5 min. It was postulated that freezing facilitate the heat-denaturation of soyprotein to enhance aggregation of soy proteins and formation of cross-linkage between aggregate and $Ca^{++}$. Frozen soybeans resulted in soybean curd which lower fat content, while protein content of soybean curd was almost he same. Frozen soybeans gave a lower yield of soybean curd, which is supposed to be caused by the more fat loss during whey-off.

• Journal of Nutrition and Health
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• v.15 no.4
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• pp.301-312
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• 1982

A series of growing and digestion trials was conducted using Sprague- Dawley weanling male rats in order to determine the effects of two protein sources (casein and ISP (isolated soyprotein) ), three protein levels (10, 20 and 30%), and two feeding patterns (ad libitum and meal feeding) on the growth, protein and energy metabolism, and body composition of rats. The total energy level of experimental diets was kept constant in 3,600 kcal ME /kg diet. The results were as follows : 1) The amount of food intake and the weight gain of meal-fed group were lower than those of ad libitum group. Though the intake of meal-fed group on 20 and 30% casein diet was only 85% of ad libitum group, it was able to gain as much as ad libitum group. 2) There were no significant differences in the food efficiency ratio (FER) and the energy efficiency (weight gain per 100 kcal GE intake) between ad libitum and meal feeding group. The FER and the energy efficiency of 20 and 30% casein diets of meal-fed group were greater than those of ad libitum group. 3) Though the gross energy intake (GE ), the digestible energy (DE) and the metabolizable energy (ME) tended to be lower at meal-fed group, the DE/GE and the ME/GE ratios for meal-fed group were the same as those for ad libitum. 4) Though meal- fed group fed less amount of nitrogen than ad libitum group, there were no differences in nitrogen balance and the retention of rats among the treatments. Actually meal-fed group retained more nitrogen than ad libitum group at the levels of 20 and 30% dietary protein. 5) After growing and digestion trials, the body composition of rats was constant among all treatments. Significantly high negative correlation coefficient (r = -0.77) was found between the body fat content and the body moisture content. Consequently, this study suggests that meal- fed group on 20 and 30% casein diets has shown more effective utilization of the ingested food and energy than ad libitum group, and increasing tendency of weight gain and the body fat deposition. Those influences of meal feeding pattern in rats were more effective on the casein diet than on the ISP diet.

• Korean Journal of Poultry Science
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• v.13 no.2
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• pp.209-219
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• 1986

This study was designed to investigate the effects of various sources of dietary fats on the blood and liver cholesterol(CHOL) levels in young Single Comb White Leghorn male chicks, In experiment 1, corn oil, palm gil, tallow and fish oil were added individually at a level of 4% to semipurified type diets composed of isolated soyprotein and glucose as major components. The diets were fed ad libitum for a period of 15 days. In experiment 2, various fats such as corn oil, soybean oil, repeseed oil, palm oil, tallow, fish oil and hydrogenated fish oil(HFO) were added individually at a level of 11.4% to practical type diets primarily based on corn and soybean meal. Control diet contained 3% of corn oil. All these diets were formulated to contain equivalent amount of nutrients such as protein, vitamins and minerals on a basis of unit kcal of metabolizable energy. The third Experiment was to compare the effects of different levels of calorie/protein(C/P ratio) of diets on the performances and various biological parameters in the chicks. Control diet was the same as in experiment 2. Another diet was added with 11.14% corn oil(C/P ratio=146) and the other diet with 10% corn oil(C/P ratio=164), The diets in experiment 2 and 3 were fed ad libitum for 26 days. In the first experiment, the chicks fed the diet containing vegetable oils tended to grow faster and show better feed efficiency without significance than those fed diets added with animal fats. However, this tendency was not observed in the experiment 2. Birds consumed the diets added with fish oil appeared to have heavier liver weight and higher liver CHOL than the others(p〈0.05), No significant differences in the levels of blood CHOL and triacylglycerol(TG) were observed among the chicks of various dietary groups(Exp. 1). Weights of liver or heart were significantly heavier in the chicks consumed the diets added with HFO or fish oil, respectively(Exp. 2). However, chicks ingested diet containing fish oil appeared to have significantly lower plasma CHOL. No significant differences were observed in the levels of liver CHOL and plasma TG among the dietary groups. Birds consumed the diet with a wider C/P ratio resulted in higher liver TG levels in experiment 3(p〈0.05). Although no statistical differences were observed among the various dietary groups, chicks fed the diet with a wider C/P ratio tended to show higher levels of plasma CHOL, TG, liver CHOL and total liver lipids compared to those of the control group.