To investigate the applicability of a gamma-ray irradiation for extending the storage life of fruits, measurements of pasteurizing effect, peel appearance, flesh flavor and taste, weight loss, sugar content and total acidity have been made on Satsuma mandarin and peach (Kurakata Wase) irradiated with the dose 300 krad of gamma-ray during the room- and low temperature storage.
It was confirmed that irradiation and low temperature storage combination was a very useful method to prevent Satsuma mandarin and peach from decay during the post-irradiation storage.
No marked influences of gamma-ray irradiation on the patterns of weight loss, sugar content and total acidity of Satsuma mandarin were detected, expect that off-flavor in flesh of fruits and the browning of peel were appeared during storage. However, off-flavor had a tendency to disappear after 40 day's storage at temperature 3-5°C, therefore, the gamma-ray irradiation might be applied to the long term storage of Satsuma mandarin for processing.
The appearance and taste of peach irradiated were mainatined for about one week, and the brown rot growth of fruits was markedly suppressed using the gamma-ray irradiation and the low temperature storage.

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A series of storage tests is conducted comparing paddy with brown rice, cold storage with ambient temperature one, under the dose of 0 krad, 30 krad, 300 krad and 1 Mrad irradiation by Co-60.
Overall count of survived bacteria for a grain is at the order of 10⁶ with non-irradiated grain, on the other hand 10⁵ with 30 krad, 10⁴ with 300 krad and 10³ with 1 Mrad irradiated one respectively, although the count decreases as the storage period increases in any cases. The decreasing rate of bacteria is less in case of paddy and cold storage than that of brown rice and ambient temperature storage. Mold disinfected grain decreases absolutely under the dose of 1 Mrad, and it increases in any cases as the storage period prolongs.
Germination ratio does not show significant change in cold storage, however, it decreases evidently as the storage period goes by in ambient temperature storage.
Significant deterioration of organoleptic evaluation is observed at 30 krad irradiated rice, but it recovers after the storage 10 months.
The irradiation technique may be useful as a supplement of common grain storage method which applied drying and storing in low temperature.

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This investigation was carried out to examine some of the physical characteristics of grain dust for the purpose of maintenance of clean environment and design of dust collection equipment, and to evaluate some parameters concerning morphological properties of grain dust. The results obtained were summarized as follows;
1) The density of grain dust had a tendency to increase with the decrease of particle diameter. The average value of the density was 1.55-1.65g/cm³, but the finer particle (less than 74μm) was larger than 1.7g/cm³. It was considered that the density might be concerned with composition of grain dust.
2) The specific surface area of the dust was not related to the particle diameter, and its constant value was estimated about 6000cm²/cm³. But the value obtained from particle size distribution curve was rather different from the above number. This seemed that the assumption of specific surface shape factor (φ) was not suitable for the calculation method.
3) From the comparison of the measured results on particle size distribution, liquid sedimentation method (hydrometer, and Andreasen-pipette method) had problems for measurement and analysis of particle size.
4) The average diameter of dust discharged from the rice drying facilities had a tendency to become smaller with the aduance of processes. The proportion of respirable dust in airborne particles was 9.1%, but in depositted dust, it was negligible.
5) The angle of contact of liquid to dust was approximately constant and independent of particle diameter. The value for water was about 90°. Hence, it was proved that wetting property of grain dust was awkward.
6) The value of φ for particle of grain hair (trichome) calculated as a model of hollow circular cone, was in good agreement with the measured value. Using this model, Some parameters concerning morphological properties of grain dust (trichome) made clear. Especially, the factor on the settling rate was considered to be a significance valae.

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