The difference of fermentation types, homo-and hetero-types, is one of the most important key to classify the genus of lactic acid bacteria. The new method which can discriminate correctly both fermentation types of homo-or hetero-type by using near infrared spectroscopy has been investigated. Spectral data (raw and second derivative) of supernatants of 10 lactic acid bacterial type strains (calibration set) were subjected to discriminant analysis with Mahalanobis distances principals. A discriminant function with second derivative absorbance at the wavelengths of 2272nm and 2311nm was derivated, which produced a sum of inverse squared distance of 0.06. This function could be successfully used to discriminate between homo-type and hetero-type of validation set of lactic acid bacteria and of strains isolated from Miso-paste products. It was suggested that 2272nm was key wavelength associated with lactic acid and ethanol. By this method, the fermentation types could be classified using a little amount of culture supernatant (5ml) within 5 min.

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'Hiratanenashi' fruit is the most popular Japanese persimmon (Diospyros kaki Thunb.) in Japan. It has fine flesh and good taste after its astringency was removed. But the fruit has very short shelf life, because of rapid softening. There are two ways for removing astringency ; 1) treatment with alcohol and 2) treatment with carbon dioxide (CO₂). The present study was conducted to investigate the relationship between the changes in fruit firmness and cell wall composition (pectic and hemicellulosic composition). (1) The rate of fruit softening was different between treatments of alcohol in 20°C for 5 days and CO₂ in room temperature for 24 hours for removing astringency, the former was more rapid softening than the latter. The respiration and ethylene production of fruits treated with alcohol or carbon dioxide were temporarily increased after the treatment. (2) Sugar of phenol-acetic acid-water (PAW) fraction from fruits treated with alcohol or CO₂ were increased, but the content of non-treated fruit did not change during storage. Soluble polyuronide contents increased in order of control < CO₂ treatment < alcohol treatment. (3) The contents of guanidium-thiocyanate (GTC) -soluble and KOH-soluble sugar from hemicellulosic components did not change in non-treated fruit during storage and the sugar content of fruits treated with alcohol or CO₂ decreased by half in 3 days after treatment. These results indicated that the fruit softening of 'Hiratanenashi' is attributable to increase of water-soluble polyuronide and decrease of water-insoluble polyuronide contents. It was suggested that the different rate of fruit softening between alcohol and CO₂ treatments were depended on a degree of increase of water-soluble polyuronide and decrease of water-insoluble polyuronide. Breakdown of hemicellulosic component did not reflect the difference of the softening by both treatments.

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This study investigated the mechanism of development of viscosity in mannan, the primary component of yam mucilage. The viscosity of the viscous polysaccharide fractions was lower for mannan obtained from the Nagaimo variety, characterized by the large number of side chains, than for the Tsukuneimo and Ichoimo varieties. Mannan aggregates due to a hydrophobic interaction which in turn results in viscosity. The number of side chains in mannan molecules has a major effect on aggregation and viscosity. A mutual relationship exists between viscosity of viscous polysaccharides of Tsukuneimo, Ichoimo and Nagaimo varieties and mannan structure.

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