The Soy Protein Research Committee(Japan)

EFFECTS OF THE SOYBEAN PEPTIDE ON AN INCREASE IN MUSCLE MASS DURING TRAINING IN MICE

Tohru FUSHIKI, Kengo ISHIHARA, Keitaro MATSUMOTO,
Ryohei UOHASHI and Kazuo INOUE

Department of Food Science & Technology, Faculty of Agriculture, Kyoto University

Rep. Soy Protein Res. Com., Jpn. 16, 1-3, 1995.

Increasing in the muscle mass of mice administered amino acid mixture simulated the soybean peptide was observed Mice were fed with stock diet and 5% amino acid mixtures solution ad libitum during endurance swimming training every 2 days for 5 weeks. The gastrocnemius and quadriceps muscle mass of the soybean peptide group were larger than those of the control group which was givin water instead of the soybean peptide. Amino acid mixture which simulated the barley protein gave the similar increase in the muscle mass when it was administered to the mouse instead of soybean peptide. However, the increase in muscle mass was rather smaller in the case of the barley protein-amino acids. The soybean peptide has much lysine, arginine and branched chain amino acids. These results suggested that soybean peptide would stimulate muscle hypertrophy during exercise training with its characteristic amino acid composition. .

INDUCTION OF HEAT SHOCK PROTEINS IN RATS FED SOY PROTEIN ISOLATE

Tetsuya HIRAKAWA, Kazuhito ROKUTAN, Shigetada TESHIMA,
Takeshi NIKAWA, Yasuhiro KIDO and Kyoichi KISHI

Department of Nutrition, School of Medicine, The University of Tokushima

Rep. Soy Protein Res. Com., Jpn. 16, 4-8, 1995.

We examined the stress-induced synthesis of a heat shock protein with molecular mass of 72 kilodalton (HSP70) and its modification by protein nutrition in rats. Male Wistar rats were fed 5% casein, 5% soy protein isolate(SPI), 20% casein, or 20% SPI diet for 3 wks and subjected to restraint and water-immersion stress. The stress rapidly induced accumulations of HSP70 mRNA and its protein within 30 min in rats fed 20% protein diets. Rats fed 20% SPI diet showed more enhanced stress response than rats fed 20% casein diet. Protein malnutrition impaired the induction of HSP70 and caused severe gastric ulcer lesion. However, when 5% SPI diet was given instead of 5% casein, it preserved the stress-induced expression of HSP70 mRNA and partially suppressed ulcer formation. These results suggest that SPI may have a beneficial effect on acquisition of resistance to stress ulcer possibly by enhancing the induction of heat shock proteins in gastric mucosa.

EFFECTS OF SOY PROTEIN ISOLATE ON SUCROSE - INDUCED FATÅ@ACCUMULATION IN LACTATIONAL MATERNAL RATS AND SUCKING BABY RATS

Eiko HARA ¹, Yasutake SHIMIZU ² and Takashi SHIMAZU ²

¹ Imabari Meitoku Junior College
² Department of Medical Biochemistry, School of Medicine, Ehime University

Rep. Soy Protein Res. Com., Jpn. 16, 9-13, 1995.

Effects of dietary soy protein isolate (SPl) on high sucrose diet-induced fat accumulation were examined in lactational maternal rats and sucking baby rats. Maternal rats were fed 30% sucrose diet with and without 20% SPI during pregnant and lactational period. In maternal rats, sucrose diet increased the liver triglyceride contents remarkably, but SPI suppressed the augmentation completely. In sucking baby rats, the liver and serum triglyceride levels were also lowered by SPI diet. Thermogenic activity of brown adipose tissue (BAT) was examined by measuring the uncoupling protein (UCP) content in the mitochondria by means of immunoblotting. In lactational maternal rats, the UCP contents were decreased markedly irrespective of the diet, suggesting that thermogenesis was lowerd in lactational period to supply energy to baby rats. In sucking baby rats, the UCP contents were not changed by SPI diet.

EFFECTS OF SOYBEAN PROTEIN ON LIPID METABOLISM IN GENETICALLY OBESE RAT

Nobuko IRITANI, Hitomi FUKUDA and Kayoko TADA

Tezukayama Gakuin College

Rep. Soy Protein Res. Com., Jpn. 16, 14-17, 1995.

The effects of dietary soybean protein on lipogenic enzyme gene expression in livers of the Wistar fatty rats have been investigated. The genetically fatty rats with non-insulin dependent diabetes mellitus are obese, hyperinsulinemic and hypertriglyceridemic, and show decreases in glucose tolerance and glycemic response to exogenous insulin. Lipogenic enzyme gene expression was markedly suppressed by dietary polyunsaturated fatty acids in the lean rats, but not so suppressed in the fatty. On the other hand, when the Wistar fatty rats and their lean littermates of 7-8 wk old were fed a casein or soybean protein diet containing hydrogenated fat (4% hydrogenated fat plus 1% corn oil) or corn oil (5%) for 3 wk, the hepatic mRNA concentrations of lipogenic enzymes were significantly lower in the rats fed soybean protein than in those fed casein, regardless of genotype and dietary fatty acid species. The conversion rates of thyroxine to triiodothyronine by liver microsomes and plasma triiodothyronine concentrations were lower in the fatty rats than in the lean, but significantly elevated by soybean protein. Conversely, the plasma and liver triacylglycerol concentrations were lowered by soybean protein in both the fatty and lean rats. Thus, it is suggested that dietary soybean protein can reduce the triacylglycerol concentrations due to the greater triiodothyronine production, which causes a stimulation of lipolysis and fatty acid utilization. Moreover, although dietary polyunsaturated fatty acids did not contribute to the suppression of lipogenic enzyme gene expression in the fatty rats, soybean protein suppressed the gene expression. The increase in body weight of the Wistar fatty rats was also significantly reduced by feeding soybean protein after 3 wk. Thus, soybean protein appeared to be a diet contributing to the reduction of obesity.

REGULATION BY SOYBEAN PROTEIN OF Éø - LINOLENIC ACID METABOLISMÅFEFFECT OF DIABETES

Michihiro SUGANO and Akira IKEDA

Faculty of Agriculture, Kyushu University

Rep. Soy Protein Res. Com., Jpn. 16, 18-20, 1995.

To know the effect of dietary protein source on the metabolism of Éø-linolenic acid under the disease state where the reduction of É¢6 desaturation is anticipated, rats were fed either casein (CAS) or soybean protein (SOY) diets containing perilla oil (Éø-linolenic acid) or safflower oil (linoleic acid) and treated with streptozotocin. Analyses of fatty acid composition of liver phospholipid indicated that the reduction by soybean protein in the linoleic acid desaturation index shown in control rats was reversed in diabetic rats. In contrast, the proportion of 20:5 n-3 increased in CAS groups. The ratio of aortic prostacyclin production to platelet thromboxane A2 production decreased only in diabetic rats fed SOY. Thus, dietary protein influenced differently on several lipid parameters between normal and diabetic rats.

SUPPRESSIVE EFFECTS OF SOY PROTEIN ON THE PRODUCTION OF PEROXIDIZED LDL AND ENLARGEMENT OF LDL MOLECULAR SIZE

Takemichi KANAZAWA

The Second Department of Internal Medicine, Hirosaki University School of Medicine

Rep. Soy Protein Res. Com., Jpn. 16, 21-31, 1995.

In human and rabbit, it was investigated whether the administration of soy protein was effective or not to reduction of plasma cholesterol, inhibition of LDL peroxidation and suppression of enlargement of LDL molecular size.
1. Peroxidized LDL and large molecular size LDL are injurious to arterial vessels.
2. Soy protein suppressed the peroxidation of LDL in vitro and in vivo experiments.
3. The increase of LDL-cholesterol after cholesterol feeding was suppressed more than that of LDL-apo B by soy protein. Namely, LDL-cholesterol/LDL-apo B ratio became lower by soy protein administration. The ratio after cholesterol feeding increased with enlargement of LDL molecules. Thus, it was speculated that enlargement of LDL molecules due to cholesterol feeding was inhibited by soy protein administration.
4. Soybean is very good food for protection of vessel injuries and prevention of cardiovascular disease.

EFFECT OF DIETARY SOYBEAN PROTEIN ON ARTERIAL LESIONS IN HYPERCHOLESTEROLEMIC (ExHC) RATS

Katsumi IMAIZUMI, Toshihiko FUKUYAMA and Masanobu SAKONO

Faculty of Agriculture, Kyushu University

Rep. Soy Protein Res. Com., Jpn. 16, 32-35, 1995.

Atherosclerotic lesions of the aorta were induced in ExHC (exogenous hypercholesterolemic) rats treated with 2Å~105 IU of vitamin D2/kg body weight for the initial 4 days and subsequently fed a purified diet supplemented with cholesterol and cholic acid for an experimental period of 72-180 days. Dietary soybean protein, as compared with casein, fed for as long as 180 days significantly decreased the degree of atherosclerotic changes in the aorta.

SOY PROTEIN ISOLATE FAVORABLY AFFECTS A POSTPRANDIAL LIPEMIA IN NORMOLIPIDEMIC SUBJECTS

Hideki SHIGE, Kenji HIGASHI, Toshitsugu ISHIKAWA, Takeshi YAMASHITA,
Koji TOMIYASU, Hiroshi YOSHIDA, Hiroshi HOSOAI, Toshimitsu ITO,
Kei NAKAJIMA, Makoto AYAORI, Atsushi YONEMURA, Emiko MIYAJIMA,
Miyuki NOMI, Miyuki TAKEMURA and Haruo NAKAMURA

First Department of Internal Medicine, National Defense Medical College

Rep. Soy Protein Res. Com., Jpn. 16, 36-40, 1995.

Postprandial lipemia has recently been considered to be atherogenic. Soybean protein has been reported to reduce plasma cholesterol concentrations in humans as well as in experimental animals. However, the effect of soy bean protein on postprandial lipemia has not been examined yet. To elucidate the effect of soybean protein on postprandial lipemia, oral fat load test was performed in normolipidemic male subjects. Eleven normolipidemic male subjects were assigned to either a 20 g/day soy protein isolate (SPI) diet or a casein diet for three weeks in a crossover design. Both diets consisted of ordinary food compositions added with 20 g/day of SPI or casein. Forty grams per square meter of body surface area of cow milk fat were administered before and three weeks after the experimental diets. Fasting plasma lipid and apolipoprotein concentrations did not change during both SPI and casein diet. Triglyceride (TG) response and Remnant Like Particles (RLP)-TG response to the fat load were not affected by both diets. However, RLP-C response area was significantly increased by a casein diet (AUC + 26.7%, P = 0.032), whereas it was decreased by SPI diet (AUC -37.5%, P = 0.071). These results suggest that SPI diet favorably alter a postprandial lipemia, particularly improving remnant metabolism, in normolipidemic subjects.

KINETIC STUDY OF EXTRACTION OF WATER - SOLUBLE POLYSACCHARIDES FROM "OKARA"

Hidefumi YOSHII ¹ and Takeshi FURUTA ²

¹ Department of Biochemical Engineering, Toyama National College of Technology
² Department of Biotechnology, Tottori University

Rep. Soy Protein Res. Com., Jpn. 16, 41-45, 1995.

Kinetics of okara-hydrolysis was investigated with an autoclave at pH 4.5 in the two fold of water to the initial wet-okara with or without the chelator, 0.5-2% sodium hexametaphosphate. The reaction of okara-hydrolysis proceeded with the surface degradation mechanism without chelator. The characterization of the extracted water-soluble polysaccharides (WSP) suggested that the egg-box regions in okara were labile for the degradation with chelator and the non-egg-box regions were in higher content of WSP bound with hydrophobic proteins. The molecular weight of WSP higher than 10 and the content of WSP bound with proteins was important for emulsifying characteristics of WSP. The hydrolysis of okara without chelator was effective for obtaining WSP as emulsifier.

EFFECT OF EDIBLE OIL ON BEANY FLAVOR FORMATION IN SOYBEAN HOMOGENATE

Teruyoshi MATOBA ¹,Hitoshi TAKAMURA ¹ and Keisuke KITAMURA ²

¹ Department of Food Science and Nutrition, Nara Women's University
² National Agriculture Research Center

Rep. Soy Protein Res. Com., Jpn. 16, 46-50, 1995.

Soybean seeds contain three lipoxygenase isozymes (L-1, L-2, L-3). Effect of soybean oil in hexanal formation in soybean homogenate was investigated by using normal and their isozyme deficient seeds. The seeds used were normal type, null type (L-1, 2, 3 deficient), L-1 type (L-2, 3 deficient), L-2 type (L-1, 3 deficient) and L-3 type (L-1, 2 deficient). The defatted homogenate prepared from a lot of null type seeds produced a high level of hexanal in the presence of linoleic acid, but the raw homogenate from its single seed did not produce. As the result of single seed analysis, L-1 type seed contaminated about 20% in the null type seed group harvested at the same season. However, the homogenate of complete null type seed produced enzymatically a low level of hexanal. Hexanal formation in other seeds was not influenced significantly in the addition of soybean oil.

GENETIC VARIATION OF 11S GLOBULIN A5 SUBUNIT IN GLYCINE SOJA

Kyuya HARADA

Faculty of Horticulture, Chiba University

Rep. Soy Protein Res. Com., Jpn. 16, 51-54, 1995.

It is well known that A4 and A5 acidic (group II) subunits of soybean 11S globulin are responsible for gel hardness and gelling characteristics of tofu gels and heat-induced gels. I have searched accessions of Glycine soja for new variants of the group II subunits. Among seeds of one accession, a few seeds were found to lack the A5 subunit but to have a novel acidic subunit (A5a,). Genetic analysis revealed that A5a, is encoded by an allelic gene at the same locus as that for the A5 subunit. The A5a subunit was found to have a molecular weight of about 27,000 and an isoelectric point of less than 3.0. No disulfide bond was detected between A5a, subunit and other subunits. The group II subunits of the mutant were separated by two-dimensional electrophoresis, and the N-terminal amino acid sequence of the A5a, subunit was determined by gas-phase sequencer. Fifteen out of twenty amino acid residues from the N-terminal were aspartic acids or glutamic acids and there was no homology with previously reported sequences of 11S globulin acidic subunits. To evaluate the effects of the A5a, subunit on properties of heat-induced gels of 11S globulin, A5a, was introduced into soybean varieties having different 11S globulin subunits.

MOLECULAR ANALYSIS OF THE MECHANISM THAT REGULATES EXPRESSION OF A SOYBEAN SEED STORAGE PROTEIN GENES IN RESPONSE TO SULFUR NUTRITIONÅFTOWARD A DEVELOPMENT OF A NOVEL STRATEGIES FOR MOLECULAR BREEDING OF SOYBEAN

Toru FUJIWARA

Department of Applied Biological Chemistry, The University of Tokyo

Rep. Soy Protein Res. Com., Jpn. 16, 55-57, 1995.

Mutants of Arabidopsis that are resistant to selenate, an analog of sulfate, were isolated for the molecular genetical analysis of sulfur uptake and assimilation. Some of the mutant lines exhibited reduced rates of sulfate uptake, which is presumably the cause of selenate resistance. A 300 bp fragment in the promoter region of a soybean seed storage protein gene was found essential for regulation by sulfur nutrition. Activity of a DNA binding factor that recognizes this region of the promoter was also regulated by sulfur nutrition. Sulfur deficiency was found to reduce free sulfate concentration in developing seeds which causes changes in the levels of a seed storage protein composition. Mutants of Arabidopsis that are defective in regulation of gene expression in response to sulfur nutrition were isolated.

CLONING OF THE GENES FOR AN ALLERGENIC PROTEIN IN SOYBEAN

Tetsuo TAKANO ¹,Isamu NOGUCHI ¹,Tao LI ² and Keisuke KITAMURA ²

¹ University Farm, Faculty of Agriculture, The University of Tokyo
² National Agriculture Research Center

Rep. Soy Protein Res. Com., Jpn. 16, 58-61, 1995.

Gly m Bd 30K is a major allergenic protein in soybean seed. We have isolated two cDNA clones for Gly m Bd 30K and we screened a genomic library of soybean using a cDNA clone as a probe. Twelve positive clones were obtained. Among them, B7 and B9 were identified to contain the genes which have homology to Gly m Bd 30K genes. DNA fragments (PB7, PB9 and PSU) which contain coding region of the protein were amplified by PCR using phage DNA of B7 and B9, and genomic DNA of variety 'Suzuyutaka' as templates. They were cloned and sequenced. Comparing amino acid and nucleotide sequences of the PB7, PB9 and PSU, it was clarified that PB9 is the different gene from PB7 and PSU. The result of genomic southern hybridization of the soybean varieties using Gly m Bd 30K cDNA as a probe also suggested the presence of two copy of the gene.

DEVELOPMENT OF HYPOALLERGENIC SOYBEAN PROTEINÅFANALYSES USING MODEL ANIMALS

Tadashi OGAWA, Rintaro YAMANISHI, Hideaki TSUJI and Noriko BANDO

Department of Nutrition, School of Medicine, The University of Tokushima

Rep. Soy Protein Res. Com., Jpn. 16, 62-66, 1995.

The allergenicity of two soy proteins was investigated using model animals. The serum from Balb/c mice immunized with Kunitz-type soybean trypsin inhibitor (KSTI), the most potent experimental allergen for Balb/c mice among soy proteins, exhibited the allergen specific reaginic activity either in the passive cutaneous anaphylaxis (PCA) test or in the micro-assay with RBL-2H3, a rat basophilic leukemic cell line. The serum from mice immunized with Gly m Bd 30K, a major allergen for patients with atopic dermatitis evoked by soybean intake, was also exhibited the allergen specific reaginic activity with the concentration dependent manner in the micro-assay. The mice immunized with Gly m Bd 30K accompanied by alum adjuvant were applied to the allergen feeding test after long interval from last immunization. The serum of mice fed with the allergen exhibited highly allergen specific reaginic activity in the micro-assay. The allergen-sensitized mice could be subjects in substitute for soybean allergic patients.

EXPRESSION OF SOYACYSTATIN IN E. Coli AND INVESTIGATION OF ITS INHIBITORY ACTIVITY

Soichi ARAI

Department of Applied Biological Chemistry,
Division of Agriculture and Life Science, The University of Tokyo

Rep. Soy Protein Res. Com., Jpn. 16, 67-69, 1995.

Cystatin is a proteinaceous inhibitor against cysteine proteinases. Soyacystatin is a phytocystatin which has been cloned from soybean seed. Soyacystatin protein has extension sequences in NH2- and COOH-termini. The effect of extension sequences of soyacystatin against inhibitory activities was investigated. As a result, the truncated mutant of soyacystatin from which both extension sequences were deleted showed lower inhibitory activity against papain than wild type and the other mutants of soyacystatin. Therefore, the extension sequences of soyacystatin have a certain effect on the intensities of inhibitory activities. On the other hand, expressed soyacystatin protein in E. coli showed the inhibitory activity against proliferation of poliovirus in vitro. This activity is as effective as both those of other cystatins of plant origin and that of the egg white cystatin. This result indicated that soyacystatin has anti-virus effect.

BINDING OF SECONDARY BILE ACIDS TO POLYPEPTIDES FROM SOY PROTEIN, AND ASSESSMENT OF THEIR MASKING EFFICIENCY IN RELATION TO ANTITUMORIGENICITY

Kimikazu IWAMI, Masahiro KANAYA, Naoyuki ADZUMA and Ryuhei KANAMOTO

Department of Agricultural Chemistry, Kyoto Prefectural University

Rep. Soy Protein Res. Com., Jpn. 16, 70-77, 1995.

The high-molecular weight fraction of indigestible polypeptides from soy protein (HMF) was examined for its ability to trap secondary bile acids in Fischer rats fed on casein or HMF diets supplemented with and without deoxycholate. The HMF intake caused a considerable increase in the fecal excretion of secondary bile acids relative to the casein intake; implying that the colon had been exposed to high concentrations of such bile acids. Secondary bile acids are well-known to serve as risk factors for colonic tumorigenesis. For this reason, the safety of HMF against tumorigenesis was revaluated by measurement of aberrant crypt foci (ACF) in the colon of rats loaded with azoxymethane and/or deoxycholate. As a result, it was revealed that the multiplicity of ACF, but not the number of ACF, was significantly depressed by HMF feeding in DCA-loaded rats. Further study is required for assessment of the safety or antitumorigenicity of HMF.

EFFECTS OF DIETARY SOYBEAN PROTEIN, PROLEENA 200 ON PLASMA LIPID IN HYPERLIPIDEMIC AND HYPERTENSIVE PATIENTS

Hirofumi KAMBARA

Cardiovascular Center, Osaka Red Cross Hospital

Rep. Soy Protein Res. Com., Jpn. 16, 78-82, 1995.

To examine the effects of new powder-type soybean protein (Proleena 200) on lipid and blood pressure, 19 patients with hyperlipidemia and hypertension but without other systemic diseases were enrolled. All patients (6 males and 13 females) took 20g of Proleena 200 daily mixed with water or other appropriate liquid for 1 month but did not take any medications for hyperlipidemia or hypertension. Clinical and laboratory data obtained just before and 1 month after the start of Proleena 200 administration were compared. Total cholesterol in the plasma was significantly reduced from 252Å}30 (meanÅ}SD) mg/100 mL to 237Å} 25 mg/100 mL (P=0.011), and LDL-cholesterol from 172Å}30 to 157Å}31 mg/100 mL (P=0.002). No significant reduction was obtained in plasma triglyceride, HDL-cholesterol or apoprotein subfraction. Blood pressure also did not show any significant change with Proleena 200 as well as other routine blood chemistry. This, new type of soybean protein, Proleena 200 appears to play an important role in diet therapy of hyperlipidemia.

X - RAY ANALYSIS OF SOYBEAN PROGLYCININ

Shigeru UTSUMI

Research Institute for Food Science, Kyoto University

Rep. Soy Protein Res. Com., Jpn. 16, 83-86, 1995.

Glycinin is one of the most abundant storage proteins in soybean seeds. We earlier reported the preparation of proglycinins modified by protein engineering to improve food functions. Crystals of the normal and the modified proglycinins (É¢I, É¢V8, IV+4Met, V+4Met, C12G, and C88S) expressed in Escherichia coli were grown, each under different suitable crystallization conditions. The crystals of the normal, É¢I, V+4Met, C12G, and C88S diffracted X-rays sufficiently for crystallographic analysis. The normal, É¢I, C12G, and C88S crystals were tetragonal, space group P41 or P43, and with unit cell dimensions a=b=114.3-115.9Å&Mac240; and C=145.1-147.1Å&Mac240;. V+4Met crystals were monoclinic, space group P2, and with unit cell dimensions a=118.7Å&Mac240;, b=78.1Å&Mac240;, c= 109.9Å&Mac240;, and É¿=119ÅK. The number of protomers per asymmetric unit of all the crystals of the normal and the four modified proglycinins was about 3. This value is consistent with proglycinins being trimers. Moreover, the structure of the normal proglycinin trimer was determined at 6Å&Mac240; level.

IMMUNOLOGICAL RESPONSE AND TO LERANCE TO DIETARY SOYBEAN PROTEIN

Tsukasa MATSUDA, Naohito AOKI, Takahiro ADACHI and Ryo NAKAMURA

School of Agricultural Sciences, Nagoya University

Rep. Soy Protein Res. Com., Jpn. 16, 87-93, 1995.

Immune response of several inbred mice to fed soybean proteins was investigated to get information on immunogenic properties of soybean proteins. The inbred mice (A/J, BALB/c, C57BL/6, C3H/He, DBA/2, B10.A and B10.D2) were fed a purified diet containing 25% soy protein isolate (SPI) as a protein source, and blood was collected individually from each mice before and after the soy protein feeding. Measurement of serum antibodies specific for major soybean proteins such as 2S, 7S and 11S fractions indicated that no remarkable antibody response was induced in these mice by the feeding with the SPI-based diet. However, a considerable level of serum antibody to soybean proteins was shown to exist already in several mice before the feeding, probably due to the pre-sensitization by soy protein antigens contained in commercial non-purified diet used for the mouse breeding. Several antigens recognized by the pre-existing antibodies were further purified from 2S fraction, and their antigenic and trypsin inhibitory activities measured for each sub-fraction indicated that the major antigens differed from mouse to mouse and antigenic activity did not necessarily correlate to trypsin inhibitory activity. Such pre-existing antibodies to soy proteins were remarkably decreased by feeding with the SPI-based diet, suggesting that oral immune tolerance to soy protein antigens was induced by the SPI feeding.

STUDIES ON STRUCTURAL FACTOR INVOLVED IN PHYSICAL PROPERTIES OF THERMALLY INDUCED SOY PROTEIN GELS

Tomohiko MORI

Research Institute for Food Science, Kyoto University

Rep. Soy Protein Res. Com., Jpn. 16, 94-99, 1995.

Heat-set gels were prepared from 11S globulins of various soybean cultivars at protein concentrations of 18 to 20%. The gels were measured for mechanical parameters by means of a compression-decompression test. Textural properties of the gels were evaluated in terms of three-dimensional representation of the gels through factor analysis of the instrumental data and calculation of factor scores for each gel. Texture of the gels was discriminated each other in terms of two textural attributes, elasticity and fracturability, primarily, on the three-dimensional diagram, where the third attribute was hardness. Differences in gel texture were clearly observed among the soybean cultivars. Shirotsurunoko gel was the most fracturable and Yamabe-A3 gel the most unfracturable. The most elastic was the gel from Hill, and Matsuura gel exhibited the lowest elasticity. Textural feature of the gels was also different between the cultivars containing A4 subunit and those lacking A4. The gels of A4-contained cultivars were more unfracturable and less elastic compared to those of A4-lacked cultivars. Physical properties of the gels, gel network structure, and subunit composition of the l1S globulin were related each other to some extent. Compressibility which corresponds to textural attribute of fracturability was related to regularity and/or pore size of network structure of the gels. The acidic subunit of A4 seemed to be responsible for whether the gel network is aggregate or strand type, thereby relating to the physical properties, compressibility and resiliency, of the gels. The results obtained here suggest that subunit composition of the 11S globulin affects the properties of gel networks and thereby generating different physical and textural properties of the gels.

ANALYSIS OF FREEZE - DENATURATION OF SOY PROTEIN AND ITS CONTROL

Osato MIYAWAKI

Department of Applied Biological Chemistry, Division of Agriculture and Life Science,
The University of Tokyo

Rep. Soy Protein Res. Com., Jpn. 16, 100-103, 1995.

Freezing denaturation of soy protein was investigated through the behavior of water in freezing. Mean ice structure size formed in the protein gel was proved to be inversely proportional to the moving speed of freezing front. For the analysis of freezing denaturation of soy protein, the effect of freezing itself was separately analyzed from the rate process of denaturation in the storage. As for the effect of freezing itself, rapid freezing was favorable for the less denaturation as measured from the increase in gel elasticity. Frozen soy protein gel was stored at the three different temperature levels and the change in elasticity was compared. The higher temperature below the freezing point gave the higher change in gel elasticity. The addition of glucose in the gel substantially inhibited the denaturation. For the estimation of the protein concentration in the frozen gel, the ice fraction was measured by using differential scanning calorimetry (DSC). Ice fraction for the soy protein gel containing 10% glucose was much lower than that for the sample not containing glucose, which seemed to explain the slower denaturation rate for the frozen gel containing glucose.

IMPROVEMENT OF THE FUNCTIONAL PROPERTIES OF SOY PROTEIN BY SPONTANEOUS DEAMIDATION OCCURRED IN A LOW WATER ACTIVITY

Akio KATO, Nao FUJISAWA and Naotoshi MATSUDOMI

Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University

Rep. Soy Protein Res. Com., Jpn. 16, 104-108, 1995.

Soy protein (APP) was deamidated by a controlled dry-heating (relative humidity 65%, 60Åé) in an atmosphere of nitrogen gas without a drop of solubility. After 7 days storage of soy proteins, the deamidation rates were 8.2, 12.2 and 14.3 percents at pH 5.5, 8.0 and 10.0, respectively, suggesting that a considerable deamidation occurred in dry-heating. Deamidated soy proteins resulted in remarkable improvements of the emulsifying properties in proportion to the deamidation rates. On the other hand, the improvement of foaming properties was also observed by the deamidation of soy protein, regardless of the deamidation rate. These results suggest that a controlled dry-heating in an atomosphere of nitrogen gas is a useful method for improving food functionality of soy protein.

SURFACE PROPERTY OF DEHYDRATED PROTEIN OF POLYSACCHARIDE FILM AND MASS TRANSFER THROUGH THE FILM

Shuji ADACHI, Shuichi SEGAWA and Ryuichi MATSUNO

Faculty of Agriculture, Kyoto University

Rep. Soy Protein Res. Com., Jpn. 16, 109-114, 1995.

Pullulan-or sodium caseinate-based films which contained soy protein isolate (SPI) or peptide (Hinute PM) were prepared. Surface property of the films were estimated by contact angle measurements for liquids with various surface tensions. The critical surface tensions of the films were determined from the measurements. Solubility and diffusion coefficients of oxygen for the films were also measured. An addition of SPI to pullulan-based films decreased the critical surface tension and increased the permeability of oxygen. It seemed that the addition of SPI made the structure of pullulan-based film rough. On the other hand, an addition of PM to pullulan-based films gave no significant effects on both the surface property and the permeability. The critical surface tensions of sodium caseinate-based films were not affected by the addition of both SPI and PM.

SPI AS THE PRINCIPAL NITROGEN SOURCE OF A DESIGNED DIET FOR GALACTOSAMINE - INDUCED HEPATITIC RATS

Tadashi NOGUCHI, Asako TAKENAKA and Tomomi HIDAKA

Department of Applied Biological Chemistry, Division of Agriculture and Life Sciences,
The University of Tokyo

Rep. Soy Protein Res. Com., Jpn. 16, 115-118, 1995.

A diet containing soy protein isolate (SPI) as the principal nitrogen source was designed for galactosamine-induced hepatitic rats. This SPI diet contained high branched-chain amino acids and low aromatic and sulfur amino acids and was of low value nutritionally because the normal rats given this diet did not grow practically. However, when the SPI diet was given to the rats which received galactosamine (0.3g per kg body weight) every day for 8days, these rats showed a slightly but not significantly higher body weight than those fed on a 12% casein-based diet. There was no significant difference in plasma GOT or GPT between the two groups of rats. The results show that it is possible to improve the symptoms of hepatitis by taking amino acid modulated diets.

EFFECT OF INGESTION OF SOY PROTEIN ON RENAL HEMODYNAMICS IN HEALTHY VOLUNTEER SUBJECTS

Kazunori UTSUNOMIYA ¹ and Yoshio IKEDA ²

¹ Department of Internal Medicine (áV), The Jikei University School of Medicine
² Center for General Health Care, The Jikei University School of Medicine

Rep. Soy Protein Res. Com., Jpn. 16, 119-123, 1995.

Protein intake has a profound influence on renal hemodynamics and it has been recently suggested that protein restricted diet retards the progression of chronic renal disease including diabetic nephropathy. This study was designed to assess different influences in renal hemodynamics after acute loading of meat and soy protein using 3 healthy volunteers. All subjects ingested 50g of beef meat or soy protein on separate days. Glomerular filtration rate (GFR), serum atrial natriuretic peptide (ANP), and urinary excretion of 6-keto-PGF1Éø, TxB2, and c-GMP were measured before and after ingestion of each protein. There was no significant increase in GFR after ingestion of beef meat and soy protein. There was no significant change in urinary excretion of 6-keto-PGF1Éø and TxB2 after ingestion of beef meat and soy protein. There was also no significant change in serum ANP and urinary excretion of c-GMP during both protein loading. In this study, we cannot find any evidences suggesting that metabolism of prostaglandin and ANP may participate in alteration of renal hemodynamics after acute protein loading.

MEASUREMENT OF TRYPSIN INHIBITOR ACTIVITY OF DIFFERENT TYPE OF TOFU

Sumie SHINJO ¹, Yuko MIYAGI ¹, Ryoko NISHIDA ¹, Kayoko UEZU ¹,Katsumasa SHIMADA ¹ ,Shigeru YAMAMOTO ¹,Kiyoharu TAKAMATSU ² and Takashi YAMAMOTO ²

Research Center of Comprehensive Medicine, University of the Ryukyus
Applied Research Institute, Fuji Oil Co

Rep. Soy Protein Res. Com., Jpn. 16, 124-127, 1995.

In previous studies, the beneficial effects of trypsin inhibitor (TI) on the inhibition of cancer induced in animals were evident. However, intake of it in human is not recognized, because it is assumed to be hazardous. In this experiment, we tried to find the TI activity of commercially available "tofu" as the first step to find the actual intake of TI in our daily life. Average TI activity of dried raw soybean (n=4) was 4811 unit/100g. Average retention of TI in comparison to the dried raw soybean was : "Momen-tofu", 2.3% (n=7) ; "Yushi-tofu", 3.0% (n=5) ; "Kinugoshi-tofu", 4.4% (n=5) and "Jyuten-tofu", 5.6% (n=1). The result indicates that we have been consuming active TI in our daily life.

EFFECT OF PROTEIN NUTRITION ON HEPATITIS AND HEPATIC CANCER IN LEC (LONG EVANS CINNAMON) RATÅF(2)FEEDING OF F1 (LEC Å~ FISCHER) RATS A SOY PROTEIN DIET WITH OR WITHOUT ADDITION OF METHIONINE

Naoki SUGAWARA ¹, Chieko SUGAWARA ¹, Motoyuki YUASA ¹,Yu-rong LAI ¹, Hirotsugu Miyake ¹, Michio MORI ¹,Akihiro YAMAGUCHI ² and Tomoki OHOTA ³

¹ School of Medicine, Sapporo Medical University
² Sapporo City Institute of Public Health
³ Hokkaido Food Processing Research Center

Rep. Soy Protein Res. Com., Jpn. 16, 128-132, 1995

The LEC rat suffers from spontaneous hereditary hepatitis and liver cancer. The severity of the hepatitis and incidence of hepatic cancer depend on nutritional conditions, for example protein components. We prepared soy protein (12.5%) diets containing methionine at the level of 0.13% or 0.43%. F1 (LEC Å~ Fischer) male rats were fed the diets for 35 days from 70 days of age. With the low methionine diet (0.13%), hepatic GGT (É¡-glutamyltranspeptidase) activity was higher in F1 rats than in Fischer rats. However, the low methionine diet led to larger decreases of the serum homocysteine concentration in the F1 group than in the Fischer group. The correlation coefficient between liver GGT activity and serum homocysteine was significant (P ÅÉ0.01) for all groups of rats. The high sensitivity for methionine shortage found in F1 rats may be implicated in their high susceptibility to chemical carcinogens.

The soy protein protein reserch(Japan)