Powdered natural derived colorants, such as beet red, red cabbage, cochineal extract, carthamus yellow, gardenia yellow, kaoliang, annatto and spirulina colors, inoculated with 3×10 ⁴ counts/g of Bacillus subtilis were irradiated with an electron beams at doses of 2.5kGy to 40kGy. All the colorants were sterilized completely by 10kGy of irradiation. Influences of irradiation on colorants were examined by measuring color tones, color values and visible absorption curves and HPLC analysis. Slight color tone changes and decolorizations by irradiation were detected but they were smaller than those by sterilization with heat. Electron beam irradiation was a practical technique for sterilizing powdered food colorants, which is easy and results in high level of sterility without any adverse effect on the color tone.

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Differential scanning calorimetry (DSC) was used to study the gelatinization of starches inside cotyledon cells of adzuki bean (Vigna angularis) and isolated starches. DSC thermogram of cotyledon cells showed a endothermic transition with peak temperature at about 70°C which trailed a shoulder up to about 98°C, although that of isolated starches showed a single endothermic transition with peak temperature at about 71°C. The transition enthalpy (cal/g starch) for cotyledon cells was nearly equal to that for isolated starches. From these results it was assumed that the endothermic phenomenon at 70°C of cells was ascribed to the starch gelatinzation taken place by the same mechanism as that of isolated starches and the higher temperature transitions were ascribed to the starch gelatinization inside cells at higher temperatures, which suggested that the gelatinization of starches inside cotyledon cells was suppressed. Cotyledon cells were subjected to such treatments with pectolyase or cellulase under appropriate conditions that caused an rupture of cells by swelling of starch granule accompanied by gelatinization of starches inside cells. DSC thermograms and the transition enthalpy (cal/g starch) obtained for the cells previously treated with enzymes were almost the same as those for isolated starches except that a small shoulder was observed at about 75°C. Thermograms for isolated starches were not affected by the addition of adzuki protein. From these results it was assumed that the suppression of gelatinization might be related to the physical strength of cell walls and the limited supply of water required for the gelatinization of starches inside cells.

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Browning of shiitake was inhibited by packaging with polyethylene film bags (PE). In order to clarify the inhibitory effect on browning of shiitake, we investigated the relation between gas composition and browning of shiitake with PE packaging or by treating with ethyl alcohol (EtOH) vapor in desiccator. Concentration of EtOH in tissues of shiitake packaged with PE increased during storage (15 mM, 6days storage at 20°C), and there was a negative correlation (r=-0.75**) between EtOH concentration and browning-index. Treatment of air+EtOH inhibited the increase in both browning-index and polyphenoloxidase activity. The inhibition of browning in the treatment of CO₂ 10%+0₂ 1%+EtOH was more effective than in air+EtOH. On the other hand, the inhibition of polyphenoloxidase activity was identical with both of two treatments. From these results, we suggested that the inhibition of browning in shiitake packaged with PE was not directly caused by high CO₂ and low 0₂, but resulted from endogenous EtOH accumulation in shiitake under the conditions of high CO₂ and low 0₂.

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Miso was prepared from buckwheat, and its characteristics were compared with other types of miso. Koji were prepared from buckwheat, rice or barley, respectively, and their enzyme activities were measured. Neutral and alkaline protease activities of buckwheat koji were higher than those of others. Each koji was mixed with cooked soybean, salt and yeast, and they were incubated for 30 days at 25°C. Chemical components, color and the number of yeast in the miso were measured every ten days. Buckwheat-miso showed at least the same or higher values when compared with other miso, except for the degree of sugar degradation and color lightness. The free amino acid content of buckwheat-miso aged for 30 days was much higher than those of others. Rutin was recognized in buckwheat-miso.

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It is generally accepted that brined ume fruit treated with Ca(OH)₂ becomes hard in texture, though in some cases wrinkles appear on the peel of the brined fruit. The hardened brined ume fruit having wrinkles is known as shrunk fruit. Since the reason for this phenomenon hasn't been clarified, we thought that it was very important to research the mechanism of the shrinking of the hardened brined ume fruit. In this paper we report the relationships between the shrinking, maturity of fresh ume fruit, and the amount of Ca(OH)₂ added as a hardening agent, and speculate the mechanism of the shrinking. The results obtained were as follows: (1) Scanning electron microscopic observation showed that shrinkage of the fruit was a result of shrinkage of cells. (2) The shrunk fruit occurred when ume fruit used as materials was unripe, and the additional amount of Ca(OH)₂ was in small quantity. (3) The NaCl failed to permeate the ume fruit in sufficient amounts, and the acid flow from the fruit was greatly restricted. (4) The peel of the shrunk ume fruit contained markedly larger amounts of Ca than the flesh, whereas that of the hardened brined fruit contained the same amounts of Ca in both peel and flesh. (5) The flesh of the shrunk fruit contained a high ratio of water soluble pectin (WSP), but the hardened brined ume fruit contained very little WSP. As a result, it was found that the shrinking of the hardened brined ume fruit occurred when unripe ume fruit was used as a material and the added Ca(OH)₂ was in small amounts. It was presumed that the shrinking might occur by the change of permeability of peel resulting from the difference in tissue structure of the peel and flesh.

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To investigate change in solubility of an acetic-acid-soluble protein during fermentation, the constituent polypeptides of acetic-acid-soluble glutenin from fermented dough were fractionated. Using differential solubility to 70% ethanol, the polypeptide components of the reduced and cyanoethylated glutenin from the fermented dough were fractionated into three fractions (AF-1, AF-2, and AF-3). SDS-PAGE analysis showed that AF-1, AF-2, and AF-3 were polypeptides mainly containing aggregative, high molecular weight, and low molecular weight subunits, respectively. Fermentation caused to decrease in the amount of solubleglutenin fractionated by a modified Osborne's method. The phenomenon would be due to mainly decrease in the AF-1 and AF-3 fractions. However, the differences among SDSPAGE patterns from the dough at various fermentation times were almost negligible except only AF-2 from the fermented dough contained one distinct polypeptide with the lowest mobility on SDS-PAGE. The same ethanol-fractionation was applied on the flour treated with or without the purified lipoxygenase isozymes to fractionate constituent polypeptides into three fractions (BF-1, BF-2, and BF-3). Compared to the control flour not treated with lipoxygenase, the lipoxygenase treated flour showed a decrease in the amount of BF-1 and BF-3. These results suggested that lipoxygenase might cause similar changes in the solubility of soluble-glutenin as that caused by fermentation.

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This study was conducted to investigate the effects of glucose, sucrose and cornsyrup solids on the sweetness, stability and softness of ice milk, and to determine the optimum composition of these three sugars. A total of 15 ice milk specimens were prepared by assigning three content levels for each sugar type through factorial design. Thecharacteristic properties evaluated were sweetness, stability and softness. The relationship between specific sugar content and the characteristic properties was analyzed by the response surface methodology. As a result, regression equations with multiple correlation coefficients of 0.76 to 0.95 were developed for each characteristic property. We found that (1) increasing glucose content degraded stability, though it softend the texture; (2) increasing sucrose content improved sweetness and stability; and (3) increasing corn syrup solids content improved stability. The interactions between the sugar types were also discussed. The optimum sugar composition satisfying the conflicting nature of the quality requirements was obtained from response surface maps.

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The thermal gel-formation properties of oval filefish muscle proteins in the presence of n-butanol were examined by means of thermal gelation curves, SDS-electrophoretograms, solubility tests, and changes in the fluorescence intensity caused by ANS (8-anilino-1naphthalene sulfonate). The addition of 0.3M or 0.6M n-butanol markedly accelerated the thermal gelation of oval filefish myofibrillar paste, and perfectly depressed the gel disintegration (himodori) at 60°C. In the presence of n-butanol, the actomyosin solubility dependent upon the KC1 concentration decreased and there was a marked increase in actomyosin-ANS fluorescence intensity due to heating.

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Stability of 4-methylthio-3-butenyl isothiocyanate (MTBI) was studied in an aqueous medium. Most of (E)-MTBI was degraded within 3h by shaking or sonicating and within 6h on an agar plate. (Z)MTBI was more stable. Antimicrobial activity of MTBI on 8 bacteria, 3 yeasts, and 5 fungi was estimated in a gaseous phase. The growth of fungi were strongly inhibited by MTBI in the dose range 2.5-7.5 μmol/ plate. The fact that the maximum amount of MTBI in head space was only 0.2% of the dose suggested that the antimicrobial activity of MTBI was very high.

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