Changes in Grain Bulk Properties of Japonica Paddy in a Warehouse and Processing Quality during Lower Temperature Storage

Changes in temperature, relative humidity (RH), humidity ratio, wet bulb and dewpoint temperature, and processing quality in japonica paddy bulk with moisture of 14% were determined in a large flat warehouse with controlling of quasi-lower temperature in bulk surface by air conditionings. The results showed that during March 26 to September 30, 2019, the first layer of paddy bulk had two peaks in average temperature of 22 and 25.9 ℃ on June 21 and September 2, respectively. The average humidity ratio, wet bulb temperature, in dew point temperature in the first layer at the same dates also had two peaks of 0.0117 and 0.0147 kg/kg, 18.3 and 21.4 ℃, 16.5 and 19.6 ℃, respectively. The average temperature, humidity ratio, wet bulb and dewpoint temperature in the second, third, and fourth layer all presented approximately linear increase. The average RHs in the first, second, third and fourth layer were 69.9%, 71.1%, 68.9%, and 70.0%, respectively. The moisture content in the four samplings tended to decease, and the head rice yield and appearance quality of milled rice showed no significant change, with a taste score of more than 89 in cooked rice. During 117 days from May 20 to September 13, air-conditionings ran 74 days, the average temperature in bulk surface was 21.5 ℃. The wet-bulb temperature in the first, second, third, and fourth layer were 17.7, 10.7, 7.2, and 10.5 ℃, respectively. The eggs of Rhyzopertha dominica and Sitophilus oryze in gain bulk surface finished their life cycle, and resulted in twice local fumigations from July 2 to July 7, and August 6 to August 16, and finally a whole warehouse fumigation from September 23 to October 9.