FLASH DRYING TECHNIQUES FOR SHELLING HIGH MOISTURE ROUGH RICE (QUALITY, POSTHARVEST, TECHNOLOGY).

摘要

Shelling high moisture rough rice is not a new idea. Various studies have been done globally but they have had limited success because the physical properties of the grain were ignored. In this study, causes of fissures in the rice grain were reviewed and analyzed. The analysis led to a flash drying technique that has essentially eliminated the fissures from developing after drying.;The best overall sequence was either with the two flash drying treatments using 316(DEGREES)C for 5 seconds per treatment with a 10-second period between them or with one flash drying treatment using 316(DEGREES)C for 10 seconds followed by a 10-second cooling interval.;Treatment effectiveness was evaluated in terms of shelling efficiency, moisture removal, brokens ratio after shelling and fissured grains 72 hours after drying. Shelling efficiency, moisture removal and gemination percentage were significantly affected by flash drying temperature, time and sequences. However, the brokens ratio and percentage of fissured grains were independent of flash drying time, temperature and sequences but were closely related to the moisture content and the percentage of fissured grains in the original sample.;A logarithmic drying model was developed to describe hull flash drying, shelling efficiency and germination percentage. The model parameters were estimated using the non-linear iterative procedure of the statistical analysis system (SAS).;Hulls on high moisture rice were flash dried with drying air temperatures of 204, 260 and 316(DEGREES)C (400, 500 and 600(DEGREES)F) for time periods of 2, 5, 10, 15 and 20 seconds. Sequences consisted of : (1) one flash drying treatment with no cooling interval, (2) one flash drying treatment with a 10-second cooling interval and (3) two flash drying treatments with a 10-second cooling interval between them.;Research was conducted with the Labelle variety of long grain rough rice. However, results generally should be applicable to other varieties as well.