A method was described for the analysis of soybean protein products in meat products, using gel permeation chromatography. This method is based on the analysis of a saccharide component found in soybean protein products which shows the same behavior as starch but is not digested by amylase.When the saccharide component is submitted to gel permeation chromatography, the chromatogram shows a peak around molecular weight 50×10⁴.The height of the peak differs with each kind of soybean protein products but linearity was recognized for respective kind; thus it is possible to make a quantitative determination. Monosaccharides composition of the saccharide component were limited to rhamnose, galactose, glucose, arabinose, xylose in all of the soybean protein products examined. From the quantity and ratio of these monosaccharides composition, it seemed possible to estimate various soybean protein products.
It is not possible to obtain a generalized value as a “peak height” for various soybean protein products, and therefore this method is used only for detecting them in meat products which contain uncharacterized soybean protein products. Quantitative analysis of soybean protein products, however, can be made in cases of the meat products containing those of which “peak height” is known. We applied this method to various meat products samples with varying amounts of various soybean protein products, and got reasonable values with a coefficient of variation less than 12% (one mesurement).

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In order to elucidate the interaction between muscle contractile protein (myosin B) and soybean protein (Cold Insoluble Fraction: CIF), rheological value, water holding capacity and solubility of the gel after heat treatment were determined. Gel filtration and SDS-polyacrylamide gel electrophoresis were also experimented. Especially, oxidizing agents (potassium ferricyanide, potassium bromate), reducing agent (β-mercaptoethanol) and sulfhydryl groups-blocking agent (N-ethylmaleimide) were applied to investgate the effect of disulfide bond on gel formation after heat treatment. The following results were obtained. 1) In the mixture of myosin B with CIF, disulfide bond contributed to the gel formation, which was more reflected by behavior of CIF than that of myosin B. In addition, rheological properties of the gel after heat treatment were affected by the interaction between these proteins before heating. 2) When myosin B was heated alone, it was suggested that the other bonds of the disulfide bond affected the gel formation. 3) When soybean protein CIF was heated alone, it turned out that the disulfide bond was required for the gel formation.

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Under five optimum conditions for gel formation, the effects of added Ca²⁺ or Mg²⁺ on the heat-induced gelformability were examined using a mixture of myosin B with soybean protein CIF (Cold Insoluble Fraction). The following results were obtained. 1) Rheologically, irregular networks were formed in the presence of Ca²⁺ or Mg²⁺ below 100°C which resulted in the formation of a short gel. Generally, the toughness and firmness of the gel increased with the increase of Ca²⁺ concentration, but Mg²⁺ was not as effective as Ca²⁺. 2) By a high-temperature treatment (135°C), the gel became firmer, tougher and shorter in the presence of Ca²⁺. When the gel was subjected to three-step heating, the properties of the gel were different from that subjected to the single-step heating, which was also observed in the gel formation with Mg²⁺ added. 3) When EDTA was added to the protein solution, the gel formation at 100°C or below was different from that at 135°C,i. e., gel formation was accelerated at 100°C and below by the addition of EDTA to the system, while at 135°C, it was suppressed. It was suggested from these results that a Ca²⁺ or Mg²⁺-linkage contributed to the gel formation at a high temperature (135°C), but induced the formation of irregular networks of the gel at 100°C or below.

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The conditions of curd preparation from soymilk suitable for making cheese-like fermented soy protein foods were examined. The curd frolm soymilk treafed by ultra high temperature heating method (135°C, 2 sec.) showed too low hardness, springiness and chewiness to make fermented soy protein foods. Seven coagulants including 4 kinds of salts and 3 kinds of acids, and lactic fermentation using Streptococcus thermophilus as a starter were tested for preparing curd from soymilk. The curds coagulated by the aid of calcium sulfate, δ-D-gluconic lactone and lactic fermentation were excellent in respect of texture of curds at cutting stage and whey separation. Preparation of curd was carried out with inoculation of Saccharomyces fragils and then the pressed curds were incubated for 40 days at 20°C. Hardness, cohensiveness, springiness and chewiness of the curds were measured during the incubation. The curd by lactic fermentation with inoculation of lactic starter and yeast gave the most smooth body like cheese along with the decrease of hardness, springiness and chewiness during the incubation.

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Commercial soybean lecithin was heated at 180°C for 10-120 minutes and its phospholipids were separated by three-solvent,two dimensional thin layer chromatography.Phosphatidylcholine,phosphatidylethanolamine,phosphatidylinositol and unidentified phospholipid were the major phosp holipids.They were reduced from 85.5% at initial to 15.1% by heating for 120 minutes.Phosphatidylethanolamine was decomposed completely and phosphatidylinositol and unidentified phospolipid were reduced to about one third by 10 minutes heating.Phosphatidylcholine content was about 35% after 120 minutes of the unheated soybean lecithin. Lysolecithin was not detected.

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Changes of sugar,acid and microorganisms in the liquid part of fermented turnips were investigated. The yield of lactic acid was higher when the turnips were fermented at 30°C for about a week after the preliminary pickling in which they were packed tightly into a jar with 3.0% salt and covered with a weight for pressing down at below 10°C for about a week. The trend of microbiological and chemical changes during fermentation was similar to that of sauerkraut. Although Leuconostoc mesenteroides, Streptococcus faecium, Pediococcus pentosaceus, Micrococcus, Coryneforms, Enterobacteriaceae and Pseudomonas were found in the initial stage of fermentation, soon they became extinct. Thereafter, Lactobacillus plantarum appeared to become a predominant florum and finally yeast increased gradually. Lactic, acetic and succinic acid were produced, whereas malic acid was disappeared during fermentation.

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Changes of organic acids and bacterial flora in fermented turnips during preservation at 5-20°C were investigated to obtain the following results. 1) The composition of organic acids in the liquid part of fermented turnips were mainly lactic, acetic and succinic acid at the early stage of preservation. Thereafter, lactic and succinic acid decreased, whereas acetic acid increased during preservation. Furthermore, formic and butyric acid were detected. The shelf-life of fermented turnips was less than 10 days at 20°C, 10 days at 10°C and 100 days at 5°C storage temperature. 2) Though the lactic acid bacteria and yeasts were predominant on the early stage of preservation, putrefaction took place at the end of preservation with the rise of pH by the consumption of lactic acid.

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[in Japanese]

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[in Japanese]

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