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Experimental infrared dryer was used to study the effect of rough rice temperature and air velocity on grain crack during infrared radiation and convection drying. Factorial experiment with Completely Randomize Block design was applied to the experiment at three temperature levels of 45, 60 and 75°C (equal to radiation intensities of 0.19, 0.39 and 0.58 W/cm2) and two inlet air velocity levels of 0.4 and 0.6 m/s. The result showed that the rough rice temperature (radiation intensity) and air velocity had significant effect on crack losses. Increasing the radiation intensity and decreasing air velocity caused to increase of crack percentage during drying of rough rice samples. The comparison of infrared and convectional drying method showed that grain cracks with infrared drying energy at 60 and 75 °C (0.39 and 0.58 W/cm2) were less than that with convection drying at the same temperatures. But it did not have a significant difference at 45 °C (0.19 W/cm2). The mathematical model relationship of grain crack percentage with rough rice temperature and air flow velocity was derived. Also the result show that the effect of rough rice temperature was more than air velocity on grain crack in infrared radiation drying.

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The objective of this study was to examine the effects of the fluidized-bed drying me-thod on the final quality of two varieties of Iranian rice, medium- and long grain. The re-sults were compared to that of paddy drying using a traditional method. Rough rice was treated in the fluidized bed drier at 140ºC for 2 minutes. Similar samples were dried for 8-10 hrs by the traditional method. Dried samples were dehusked and polished. Quality factors, including trade quality (head rice yield percent and whiteness), cooking quality (amylose content, gelatinization temperature, gel consistency, aroma and flavor) and nu-tritional quality (thiamine and lysine contents), were then measured for each sample. Fi-nally, the data was analyzed. Results show that paddy drying in a fluidized bed dryer would reduce the quality factors except for rice whiteness for which conventional drying is more acceptable. Therefore modification of fluidized-bed drying technique is recom-mended.