A gas chromatographic technique was investigated in order to determine water activities and equiliblium ethyl alcohol vapor concentrations correctly, in the presence of volatiles, without opening packages. Headspace gases of samples were analyzed, using a gas chromatograph equipped with TCD, Porapak S(Waters Ltd.)column and gas sampling device whose temperature was controlled. Water activities and equilibrium ethyl alcohol vapor concentrations were calculated from the contents of air, water and ethyl alcohol vapor. I it was important to keep the temperature constantly for precise results. The flexible containers which were suitable for measurements were prepared. Standard deviations in measurements of a sponge cake to which ethyl alcohol was added were as follows: water activity-0.004(C. V. 0.5%), equilibrium ethyl alcohol vapor concentration-0.008% (C. V. 1.0%).

View full abstract

A convenient and reliable method for evaluating fiber strength of soy protein dope during spinning was studied. The method applied to calculate the drags received by cylindrical body moving in the stationary fluid could be conveniently used to calculate the fiber strength during spinning. The spun-fiber strength was proportional to the protein concentration in dope. Finally fibers could not be spun when dope was prepared with less than 1.0% NaOH(pH12.20), and viscoelasticity of dope slightly increased with the laps of time and gel formation also increased. But, on the contrary, when dope was prepared with more than 1.1% of NaOH concentration(pH12.45), the viscoelastic value of dope decreased with the laps of time and showed the fluidity. By incubating dope with more than 1.1% NaOH, maturation effects could be obtained; when the dope was prepared with 1.5% NaOH(pH13.1)and incubated at 50°C for 30min, the spun-fiber strength was the highest. Ad-justing the NaOH concentration to over 1.6%, no maturation effects could be observe, and the viscoelastic value and strength of the fiber were also decreased, since dope changed to sol state and the molecular weight of the protein decreased.

View full abstract

Aqueous solution of neopurpuratin, obtained by mixed culture of Streptomyces propurpuratus with Bacillus sp. No. 751, shows a vivid purplish-red. Therefore, it's use for food colors was studied. By the physicochemical studies, it was revealed that the stability constant(log K) of neopurpuratin, chelate complex of Fe²⁺, was 14.19(pH5, 25°C)which was as high as that of EDTA and Fe²⁺. The color tone in aqueous solution on neopurpuratin was fairly stable in a wide range of pH(3.6-8.2)and was not affected by light but it's fading was observed by heating and also by the addition of chelating agents or metal ions such as Cu²⁺, Co²⁺, Fe³⁺, Zn²⁺ etc. It was possible to prevent fading significantly by the addition of reducing agents such as vitamin C. Application of neopurpuratin as food colors was studied on non-cooked foods and it was found to be available for coloring soft drinks, jellies, pickles and others. Neopurpuratin was suggested to be safe in the biological tests(acute toxicity and mutagenicity).

View full abstract

The effect of the addition of isolated soybean protein on gelatinization and retrogradation properties of starch during heating and storage was studied by measuring the enzymic susceptibility, swelling power, solubility and X-ray diffraction. The results are summarized as follows. (1)Swelling power and solubility of potato and sago starch decreased remarkably by adding isolated soybean protein. (2)During heat gelatinization of starch, the addition of isolated soybean protein caused a delay of gelatinization of all the starches examined. By the prolonged heating at 92.5°C, the degree of gelatinization reached the same level as the starch paste without isolated soybean protein. (3)During the cold storage of starch paste, the retrogradation of potato starch remarkably was accelerated by the addition of isolated soybean protein. Potato starch retrograded at the highest rate by the existence of isolated soybean protein among the examined starches. The rest of the starches were less affected by the addition of isolated soybean protein. (4)X-ray diffractogram obtained by the cold-stored starch paste with isolated soybean protein showed a much sharper pattern than the normal retrograded starch paste.

View full abstract

Recently, increasing attention is paid to effective utilization of animal blood in Japan. Processed meat products such as pork sausage, hamburg steak and smoked pork loin which contained dried pork plasma of four commercial brands were manufactured and evaluated for their quality and acceptability. The results showed that the quality of pork sausage and hamburg steak was not affected so much by the replacement of meat with approximately 10% plasma (as the weight after rehydration with four times of water) and that smoked pork loin could be added with approximately 1% plasma without marked changes in quality. However, the application of dried plasma slightly caused unfavorable effects on the texture of the products. This may be due to the insufficient gel formation of plasma which was supposed to be attributable to the low plasma content and the low heating temperature under the present manufacturing conditions. The acceptability of the products, especially flavor, was affected significantly depending on the brand of dried plasma.

View full abstract

The influence of temperature on the color of 10-30% Concord grape(Vitis labrusca L.)juice products was studied. Pale purple grape juice at room temperature(25°C)gave dark purple and became turbid at low temperature(5°C). The color density at 520nm of grape juice was increased with the fall of temperature. The increment of absorbance at 520nm of malvidin-3, 5-diglucoside solution with the change from 32°C to 7°C corresponded to the enrichment of absorbance with the decrease of 0.2pH units in pH range 1.0-3.0. However, the pH change with temperature did not explain the enrichment of absorbance accompanied by pH change. Potassium and tartaric acid were qualitatively detected in the precipitate which was separated from grape juice (pH>3.2)at low temperature. From these results, it was thought that the color change of grape juice with temperature resulted from the nucleophilic substitution reaction on anthocyanin pigment with water (hydration reaction)and a small quantity of tartar deposit.

View full abstract

Thiocyanate contents were determined for vegetables(33 samples), fruits(9 samples), fungi(3 samples)and spices(2 samples)by gas-chromatography with electron-capture detector. The recoveries of thiocyanate added to cabbage were in the ranges of 92-95%. It was found that most of foods tested contained thiocyanate. The thiocyanate contents determined by ECD-GC were n. d.-2424.34ppm (dry weight)in vegetables, n. d.-41.93ppm(dry weight)in fruits, 9.60-100.67ppm(dry weight)in fungi and 10.70-785.09ppm in spices.

View full abstract

Salted radish containing 5.5% salt was stored in an air tight bag which had been placed in a rigid container so as to touch closely. A weight stone for pressing down was put on the salted radish and the air tight bag was closed, deaerated and filled with nitrogen gas. The salted radish was stored at room temperature. Changes in pH, the amounts of alcohol and organic acids, and microbial flora in the liquid part during storage were investigated. The salted radish was stored safely from Dec. 3rd to next Jul. 6th (215 days). About 2% alcohol was produced in the liquid part at the final stage. Formation of lactic acid was depressed. After 215 days, malic acid was found over one half of that in first stage. Yeasts and lactic acid bacteria coexisted constantly throughout the storage.

View full abstract

Some cream cheeses commercially manufactured from fresh cream, whole milk and skim milk powder were examined for quality characteristics such as general composition, physical properties and microstructure. The results obtained were summarized as follows: (1)Average yield of final products was 40Okg per 1000kg of cheese milk. (2)The mean compositions of al1 21 samples were 0.92, 55.68, 33.32, 8.55 and 1.08% in acidity, moisture, fat, protein and ash, respectively. (3)Elastic modulus and adhesiveness of the cream cheese were estirnated using 11 and 10 samples, respectively. The former averaged 15.46×10⁶dyne/cmcm², the latter1.21×10³dyne/cmcm², indicating that these physical properties were liable to variation compared with chemical compositions. (4)Scanning electron microscopy for examining the microstructure of these cream cheeses revealed that remarkable structural changes occurred during cheese making: A part of fat globules was contaced with casein micelle aggregates forming amorphous clumps, while residues of fat globule fragments were fused one another and produced large clusters in every place.

View full abstract