Starch and gluten were isolated from Australian Standard White, and five Japanese wheat cultivars and breeding lines classified into three different genotypes in amylose synthesis (Wx-genes). After their properties were assessed, they were reconstituted for making Japanese white salted noodle (WSN). Rupture properties and dynamic viscoelasticity of cooked noodles were evaluated. Differences of amylose content and setback (SB) of starch were most affectable on noodle texture. Significant increase in rupturing stress (F) and index of viscoelasticitic texture (V), and significant decrease in dynamic modulus (G') were induced by replacement of the starch with lower amylose content and lower SB. Both of F and G' were significantly increased by the gluten isolated from flour showed higher gluten index (GI). Therefore negative correlation between G' and F (or G' and V) were observed among each starch, positive correlation between them were shown among each gluten. Noodles made from reconstituted flour combined low-amylose starch and high-GI gluten showed higher V and moderate G'. However, combination of low-amylose starch and low-GI gluten induced depression of G' and V. It was suggested that coexistence of hard gluten, which was able to suppress the depression of G' by low-amylose starch, was important for making WSN with favorable viscoelasticitic texture from low-amylose flour.

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Electromyographic (EMG) measurements were made of the masseter muscles of healthy adults while masticating 7g of cucumber to identify the type and degree of mastication required when eating different cultivars and thicknesses. One cultivar required a longer mastication time and higher EMG activity than other three cultivars. In all the cucumber cultivars tested, a pile of thinly sliced samples (ca. 1mm) required more mastication than a 10mm slice, as indicated by a greater number of chewing strokes, longer mastication time, and higher EMG activity per chewing stroke. Higher amplitude and later peak position per chewing stroke were observed for the thinly sliced cucumber during the first five chews; however, these differences diminished during the later stages of mastication. These facts suggest that thinly sliced cucumber requires more effort than a 10-mm slice for mastication of the same weight.

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Large deformation properties and microstructure of soybean curd (tofu) were investigated by a compression test and confocal laser scanning microscopy (CLSM). Experimental stress-strain curves for tofu were successfully modeled using the BST equation. The Network structure of proteins and the state of oil droplets in tofu were observed using CLSM without fixation and using samples with thickness as less as 1mm. Rheological parameters correlated well with the network structure of proteins but not with the state of oil droplets. These results suggest that the network structure of proteins contribute predominantly to the rheological properties of tofu.

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The methanol extracts from 27 species of wild grasses were assessed for their inhibitory effects on the growth of Escherichia coli IFO 3301, Staphylococcus aureus IFO 12732 and Bacillus subtilis IFO 13722 with the smear culture method on agar plate. About half of the extracts, including such edible plants as Reynoutmia japonica, Gnaphalium affine and so on, completely repressed the growth of one or more kind of the microbes at the concentration of 1% (w/v). The minimum inhibitory concentration values of those extracts were further determined with the twofold dilution methods. As a result, both extracts from fresh and dried sample of Euphorbia maculata, called ‘Oonishikisou’ in Japanese, had particularly high antibacterial activities against all test microbes. Furthermore, the acid and phenolic fractions prepared from the methanol extract of E. maculata were found to have higher antibacterial activities than the basic and neutral fractions. The inhibitory effects of those fractions on the growth of S. aureus in particular were 4 times as strong as that of the original methanol extract and comparable with gallic acid.

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We evaluated a non-destructive determination for preventing collapse (foaming and shrinking phenomena through evaporation to dryness) in freeze-dried food products. Three different types of miso (soy-bean paste) soup prepared with different contents on a dry solid basis were used as the food product model. Differential Scanning Calorimetry (DSC) determination was used to evaluate the freezing ratio of the miso soup. The soup was freeze-dried to evaluate the relationship between the incident of collapse and the freezing ratio. We found that collapse was completely prevented when the freezing ratio was about 95% or greater. At any solid content of the soup collapse was also prevented when the freezing ratio was 95% or greater. Freeze-dried temperature of the miso soup was changed to determine the capacitance variation, and its relationship with the incidences of collapse was evaluated. The result revealed that the incidence of collapse was about 50% at a temperature where capacitance was maximal. Additionally, capacitance of the soup was graphically differentiated, and we found that the incidence of collapse was 0% at freezing temperatures lower than the inflection point where the soup exhibited a freezing ratio of 95%. These results suggested that in preparing freeze-dried food products, collapse during freeze-drying could be prevented by continuously monitoring the capacitance of food products during freezing process, and by freezing them to a temperature at which collapse can be suppressed.

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We selected lactic acid bacteria from 36 strains which could ferment vegetables. Eight strains of these lactic acid bacteria grew well at 10°C in model pickles. They did not generate uncomfortable flavor and prevented browing of radish pickles. Especially, Leuconostoc paramesenteroides DA-1 produced very favorable flavors. Therefore, we examined the fermentation conditions of DA-1 strain in detail.

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[in Japanese]

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