tailieunhanh - Research for Agricultural Sciences:" Effect of high temperature fluidized drying and tempering on head rice yield and mechanical strength of Vietnamese rice varieties "

As a major rice exporter worldwide, the quality of rice has become a central issue for farmers in Vietnam, especially in the rainy harvest season. Therefore, it is important to dry the rice as quickly as possible to prevent damage but maintain quality. Conventional drying techniques such as flat bed dryers can take up to 8 hours (or more) to dry the moisture rice to safety. High-temperature drying can allow the rice to dry more quickly, so space and time taken to dry the rice can be shorter agricultural science. | SECTION 2 HIGH TEMPERATURE FLUIDISED BED DRYING Experimental study on high moisture paddy- Vietnamese rice varieties 75 Effect of high temperature fluidized drying and tempering on head rice yield and mechanical strength of Vietnamese rice varieties Introduction Being as a major exporter of rice all over the world the quality of rice has become a central issue for Vietnamese farmers particularly in rainy cropping season. Therefore it is important to dry rice as quickly as possible to prevent spoilage but maintain quality. The conventional drying technique such as flat bed drying can take up to 8 hrs or even more to dry the paddy to safe moisture level. High temperature drying can allow to dry the paddy faster therefore the space and time taken to dry the paddy can be much shorter. This can serve as a compact drier. High temperature fluidized bed drying technique has been investigated to be an effective method for drying high moisture rice grain which is easily deteriorated in humid tropic climate Taechapairoj et al. 2003 . In this method the rice grain are suspended by the upward-moving drying air with high velocity 2-3 m s thus paddy and air are mixed vigorously Kunze and Calderwood 2004 . Fluidized bed or fluid bed drying is applicable in the first stage of drying when paddy is required to decrease high moisture content down to 18 wet basis . Paddy then is continued to be dried at low temperature or by ambient air in storage bin Proctor 1994 Taechapairoj et al. 2003 . Alternately a multi-pass fluidized bed drying can be applied as a compact drying process. High temperature over 1000C fluidized bed drying of paddy has been reported by a few researchers. But normally it is recommended that hot air drying temperature should not exceed 1500C to avoid the adverse effect on the whiteness of rice. The lower range of drying temperature 40-1500C has been also investigated by Tirawanichakul et al. 2004 . They reported an improvement on the head rice yield when the drying .