The application of Petrifilm SM_®, Spiral plating®, Pro·media MT-21® and Colilert® methods for bacterial counting and total coliforms in pickled vegetables (Asazuke) were examined. Petrifilm SM®method, pour plate method and Spiral plating®R method were compared to determine standard plate counts of 127 pickled vegetable samples. Correlation coefficients of Petrifilm SM®R plate versus pour plate and Spiral®R plating method was 0.991 and 0.962, respectively. The replicate variances of these me thods were not significantly different at 5% level. Total coliforms of 137 pickled vegetable samples were determined by using brilliant green lactose bile broth (BGLB) tubes, Pro·media MT-21®R cups and Autoanalysis Colilert®R tubes. The results of these methods after incubation for 48±3h were closely coincided at the rate of 86.1-92.0%. Within 24±2h incubation, 89% of total coliforms could be detected by Pro·media MT-21®R method. The presence of E. coli was confirmed by fluorescence undera longwave (366nm) UV irradiation by Autoanalysis Colilert®R test.

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To improve utilization of whey protein concentrate (WPC) and whey protein isolate (WPI), effects of pH, sodium chloride (NaCl) and calcium chloride (CaCl₂) on heat aggregation of WPC and WPI were investigated by determining changes in turbidity and viscosity. A time course of turbidity was measured by heating at 2°C/min from 30°C to 95°C. The turbidity of WPC and WPI solution at pH 5.0 was increased from 75°C. The rate of turbidity of WPI solution was higher than that of WPC. Turbidity changes of WPC and WPI solution were observed from addition of 50 mM NaCl and 100mM NaCl, respectively. The turbidity of WPC solution by addition of 1 mM CaCl₂ was increased from about 72°C. The turbidity changes of WPI solution by addition of 1, 2, 5 or 10mM CaCl2 were sharply increased at the temperature from 72°C to 82°C, from 65°C to 75°C, from 55°C to 70°C, and from 50°C to 65°C, respectively. When WPC and WPI solution were heated at 80°C for 15min, viscosity of those was determined. There was little effect of pH on viscosity of WPC and WPI solution. Viscosity of WPI solution added 200mM NaCl was markedly increased by heating. The viscosity of WPI solution was increased by addition of CaCl2, and furthermore it was remarkably changed by heating. These results suggested that desirable coagulates of WPI were formed by adjustment of pH and addition of CaCl₂.

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Organic acids such as fumaric, malic and lactic acids are produced by associativeg rowth of fermentative microorganisms and contribute largely to flavor of fermented foods. In the present study, an attempt was made to select lactic acid bacteria producing strong fumarate hydratase (EC 4.2.1.2, known as fumarase) to transform fumarate to L-malate. Forty-nine strains of lactic acid bacteria were assayed for the ability exhibiting the conversion of fumarate to L-malate in cell suspensions incorporated with disodium fumarate and toluene. The ability was determined by an enzymatic method and high performance liquid chromatography. Most stains of Lactobacillus species showed high ability to transform fumarate to L-malate, although Streptococcus, Enterococcus, Lactococcus and Leuconostoc species had weak L-malate-producing ability. Among the tested strains, Lactobacillus delbruechii subsp. bulgaricus strain 7235 exhibited the highest ability of L-malate production in the reaction mixture without sodium chloride, whereas Lactobacillus delbruechii subsp. lactis strain 1135 was the highest in the reaction mixture supplemented with 5% sodium chloride. The optimal pH of L-malate-producing ability in strain 7235 and strain 1135 were 6 and 7, respectively, and higher L-malate production by both strains was observed in the range from 30 to 45°C. L-Malate production by strain 7235 and strain 1135 was maximal at the concentration of 3% and 10% sodium chloride, respectively.

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Basic 7S globulin, an unique protein in soybean seed proteins, was detected in the residue of soymilk production (Okara). A new preparation method of the protein from Okara was studied. Though the basic 7S globulin was not extracted with water, the protein was extracted with 0.3M NaCl, denaturant (6M urea or 0.1% sodium dodecyl sulfate) or a high pH solution, indicating that the protein associated with Okara through non-covalent bonds. On the other hand, the basic 7S globulin was not extracted even with the denaturants at 60°C or above. The two subunit bands (HMWS and LMWS) of the basic 7S globulin were observed in an extract with the denaturant containing 2-mercaptoethanol at 0.02M or above even in this high temperature. After heating with a solution containing N-ethylmaleimide, an intermidiata subunit band (IS) of the protein was detected. These results indicated that the protein easily made crosslinks through disulfide bridge upon heating. The basic 7S globulin extracted from Okara was purified on CM-Sepharose CL-6B. Two fraction (F1 and F2) obtained were 85kDa and 42kDa by HPLC. The electrophoretic patterns of the fraction, however, showed the same on SDS-urea electrophoresis, which suggested that the F1 fraction contained the dimer and the F2 fraction contained the monomer of the protein. The yield was 2.2% of soybean seeds. This preparation method was better than the previous methods on the yield and reproducibility.

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Tofuyo is an excellent vegetable protein food, and is made from tofu by the action of microorganisms in Okinawa Prefecture, Japan. In this study, changes in chemical composition, soybean protein and each nitrogen compound of tofuyo prepared by Monascus fungus during fermentation were investigated. Crude protein and crude fat contents of tofuyo decreased, but its reducing sugars increased during a ripening period. Sodium chloride content of the product was almost constant (around 3%) throughout the ripening period. Digestion of soybean protein during fermentation was examined by slab polyacrylamide gel electrophoresis. Some polypeptide bands of soybean globulin such as α'-, α-and β-subunits in β-conglycinin and acidic subunit in glycinin in the water-insoluble fraction of tofuyo disappeared after 3-month ripening but that of basic subunit in glycinin still remained. It was found that main component which formed the body of tofuyo consisted of basic subunit in glycinin and other polypeptides (Mr. 55 KDa, 11-15KDa). Some polypeptide bands in the water-soluble fraction of tofuyo, which have 31, 25, 23, 21, and 12-10 KDa of molecular weights, were disappeared during the ripening period (0-3 months). The ratio of water soluble nitrogen to total nitrogen (called protein solubility ratio, or ripening ratio) reached to 36.3% after the 3-month ripening. The ratio of 4% trichloroacetic acid soluble nitrogen to total nitrogen reached to 35.0% after the 3-month ripening.

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Dried radish chip extracts (DRCE) as a curing ingredient were added to nitrite-free sausage formulas and its effect was investigated through the color, flavor and preservative qualities of sausages. Experimental results showed that pork sausages manufactured with DRCE could produce NO₂- levels that were enough to develop the characteristic color of cured meat products during a shorter period of curing for only 4 days. However, for the pork sausage added DRCE at a level of 1%, the coexistence of sodium ascorbate as a reducing agent was necessary to maintain the stability of the characteristic color of cooked cured meat products during refrigerated storage after cooking. DRCE also possessed antioxidant activity, which was enhanced in the presence of sodium ascorbate. Further results obtained suggested that the given levels of DRCE might have antimicrobial effects in pork sausage samples. The taste and aroma acceptability of frankfurter sausage samples treated with DRCE at a level of 1% or 3%, respectively, could be favored over those of the corresponding samples with DRCE added at a level of 0% or 5%. The sausage samples with DRCE added at a level of 5% possessed a distinct radish-like flavor. The 1% or 3% level of DRCE with sodium ascorbate was found to be well suited to use in nitrite-free sausage formulas, ensuring the development of the characteristic color and flavor of cooked cured meat products.

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Antimicrobial substances in methanol extracts (room temperature, 48h) of Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) were investigated. The results were as follows: (1) All extracts of stems and leaves, roots, seeds and etiolated seedlings had antimicrobial activity. The extract of etiolated seedlings showed the strongest antimicrobial activity among them. Furthermore, coixol which was known as a physiologically active substance of Adlay had no antimicrobial activity. (2) The antimicrobial activity of etiolated seedlings was measured in each growth stage. The extract of etiolated seedlings which were 2cm length after germination, showed the strongest antimicrobial activity. (3) The extract of etiolated seedlings showed the strong antimicrobial activity against bacteria, yeast and fungi. This result suggested that the antimicrobial substances had a wide-ranging antimicrobial spectrum. (4) The antimicrobial substances of etiolated seedlings had heat resistance, as it showed stable activity even after heating at 120°C for 20min.

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The existence of limonoid in the tissue of Banpeiyu (Citrus grandis Osbeck forma Banpeiyu) leaves were investigated by HPLC and microscopy. Microscopic observation revealed that limonoid was localized in the phloem of the stem. Around the cortex cells there existed dark materials which were insoluble in water and soluble in dichloromethane, acetonitrile, ethyl acetate and chloroform. As limonoid in the Banpeiyu leaves 3.7ppm of limonin, 20.4ppm of nomilin and 4.5ppm of obacunone were detected. The crystalline substances extracted from the Banpeiyu leaves provided the same retention time as nomilin by HPLC analysis.

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The conditions of lactose hydrolysis and oligosaccharides formation of purified β- galactosidase from Alternaria alternate was studied. As the results of HPLC and enzymatic analysis, the β-galactosidase formed 6 kinds of oligosaccharides. It was assumed that 5 kinds were disaccharides and one kind was trisaccharide. There was the high posifive correlation between amount of liberated glucose and oligosaccharides. Formation of oligosaccharides was accelerated in high substrate concentration and high reaction temperature. Amount of oligosaccharides formed in lactose hydrolysis reached maximum at the optimum pH, 5.0-5.5. The rate of oligosaccharide formation on alkaline side was higher than onacdic side, and the kinds of oligosaccharides were different in different reaction pH.

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The dual-wavelength spectrophotometry was compared with the standard of JULIANO in which blue color of starch developed by reactioh with iodine to measure amylose and amylopectin contents in their mixture colorimetrically. The dual-wavelength spectrophotometry gave a more accurate blue color value of both amylose-iodine and amylopectin-iodine in their mixture than the standard method. Based on the amylose and amylopectin contents determined by the dual-wavelength spectrophotometry, the amylopectin contents or the proportion of amylose to amylopectin was considered to affect the difference in the eating quality of cooked rice among cultivars rather than the amylose contents.

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In a mixing process of preparing cream puff paste, mixing of air occurs with dispersion of ingredients. In this study, to investigate the influence of air mixing and homogeneity of the paste upon volume of baked cream puff, eggs were mixed with water-fat-flour mixture in a vacuum mixing apparatus under three different atmospheric pressures (160, 460, 760mmHg) and three different periods. Results were as follows: 1) Softness and whiteness of the paste increased with mixing period, but no significant correlation was observed between the volume of baked cream puff and either softness or whiteness of the paste. 2) The total volume of air bubble in the paste or the specific gravity of paste was significantly correlated with the volume of baked cream puff. 3) When the total volume of air bubble was 1% level, a sufficient expansion of baked cream puff was not observed regardless of mixing period or the extent of homogeneity of paste. 4) When the total volume of air bubble was 5% level, the volume of baked cream puffvaried depending on the mixing period or the extent of homogeneity of paste. These observations indicated that the size and the number of air bubble in paste should play an important role in the expansion of baked cream puff.

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The incubation condition of potato tubers prior to impedance measurement greatly influenced the reliability of detection of irradiated potatoes; the impedance ratio at 5kHz to 50kHz (Z_5k/Z_50k) determined at 22°C at an apical region of tuber which was pre-incubated at 22°C for 3 days or longer resulted in the best detection of radiation treatment of potatoes. The impedance ratio was dependent upon dose applied to potato tubers. Potatoes irradiated at 100Gy could be distinguished from unirradiated potatoes for 10 cultivars of potatoes. The impedance ratio of potatoes irradiated at the same dose was little influenced by the planting locality if the cultivar was the same, although the ratio varied with potato cultivars. These results indicate that irradiated potatoes can be detected if the potato cultivar is known. Potatoes 'Danshaku' commercially irradiated at the Shihiro Potato Irradiation Center could be differentiated from unirradiated 'Danshaku' at different planting localities; the impedance ratio was lowerthan 2.75 for the unirradiated potatoes and higher than 2.75 for the irradiated ones.

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[in Japanese]

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