Seishu Tojo

X-ray CT imaging and quality detection of peach at different physiological maturity

Peach fruit at five different physiological maturities were X-ray scanned at different ripening stages. X-ray computed tomographic (CT) images of peaches at different maturity levels and ripening periods were compared. The effect of maturity and ripening on the X-ray absorption expressed in CT number and the physicochemical constituents of peach fruit were determined. Peaches were evaluated for values of CT number, density, moisture content, soluble solid, titratable acidity and pH. The CT number, density, moisture content, and titratable acidity decreased significantly with increased degree of maturity. Soluble solid and pH increased with increased maturity grade. Similarly, the CT number, density, moisture content, and titratable acidity decreased significantly with postharvest ripening time. The soluble solid and pH increased significantly as ripening time was prolonged. X-ray CT scanning could prove useful in monitoring the internal changes of peach fruit.

Measurement System of Air Permeability and Airflow Resistance in Soil Deodorizer

Soil deodorizer has been widely used in Japan since 1970’s. One of challenges on soil deodorizer is to reduce energy consumption of blower towards a low carbon society. Measurement system for air permeability was examined to real soil filter of the deodorizer. Air permeability of soil filter could be measured precisely by using soil sample of 60 mm in diameter and 150 mm in height with confined pressure. Darcy’s law for airflow in soil filter was true under the airflow rate of 50 cm3 s-1 in this test apparatus. To reduce airflow resistance, treatments of improving soil structure were tested. Effect of the repetitive process of water intake & drainage and air movement on reducing airflow resistance was clarified by measuring air permeability of soil filter.

Effect of bacterial stress on hydrogen fermentation microflora

In this study, we investigated effects of bacterial stress treatment on domination of hydrogen producing bacteria. As the bacterial stress treatment to control hydrogen fermentation microflora, we tested heat stress (105°C , 2 h ) and freeze-thaw stress (a total of 3 cycles, each including -15°C, 12 h and 4°C, 6 h ). The effect of bacterial stress on glucose hydrogen fermentation characteristic was determined by batch test using glass bottles. The results of the batch cultivation indicated that hydrogen fermentation characteristics differ among the stressed microflora. This result suggests that each original seed source has the suitable bacterial stress treatment to increase the hydrogen production. At the same time, we conducted 16S rRNA gene based analysis of hydrogen fermentation microbial community by PCR-minigel-single-strand conformation polymorphism (PCR-minigel-SSCP) method. Clostridium species such as Clostridium butyricum were identified from hydrogen fermentation batch culture.