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Nghiên cứu khoa học nông nghiệp " Fluidised-bed drying experiments "

Trong nghiên cứu trước đây, đáp ứng bề mặt (RSM) Phương pháp thử nghiệm để sấy tối ưu điều kiện đã được xác định trong điều khoản của HRY bằng cách sử dụng một máy sấy giường lò tầng sôi nhiệt độ cao. Nhiệt độ không khí sấy và thời gian trong lần chạy đầu tiên các thí nghiệm RSM (75-87oC và 2,5 phút) đã được sử dụng có hiệu quả về tốc độ sấy và HRY. Ở điều kiện tối ưu, năng suất lúa đầu (HRY) đã tìm thấy gần như tương tự như các mẫu được kiểm soát. Tuy nhiên, cảm giác Thí. | Appendix 1 Fluidised-bed drying experiments INTRODUCTION In the previous study Response Surface Method RSM experiment for optimum drying condition has been determined in terms of HRY using a high temperature fluidised bed dryer. The drying air temperature and time in the first pass of RSM experiments 75-87oC and 2.5 mins has been used effectively in terms of drying rate and HRY. At optimum condition the head rice yield HRY has found almost similar to the controlled sample. However sensory experiment has shown that the whiteness of optimum sample was lower than of the controlled sample. This has reduced the sensory score of the optimum sample. Statistical analysis has also indicated that first drying pass affected remarkably on the colour of the samples. In this period the tempering time in the first pass was thought to be a factor affecting the colour of the cooked rice samples. The objectives of this experiments were to study the effect of tempering time and drying air temperature of the first pass on i the whiteness of the cooked rice ii moisture removal rate of paddy in the ventilation stage and iii head rice yield. MATERIALS AND METHODS Fluidized bed dryer A batch lab-scale dryer HPFD150 developed at the Nong Lam University Vietnam was used in this study. This dryer consists of three main components i a cylinder shaped drying chamber 40 cm in height and 15 cm in diameter ii two 5 kW electric heating units and iii a centrifugal fan driven by a 0.75 kW motor. The inlet drying temperature range of 20-100 oC was monitored by a temperature controller Hanyoung Electronics Inc. Model DX7 Seoul Korea . The outlet drying temperature was monitored by a Daewon thermocouple. Rice samples Freshly harvested paddy of OM4900 was collected at Kien Giang Province during March 2009. These paddies were cleaned transferred to laboratory and kept at 4 - 5 oC. Before drying remove paddy from cooler and soak in water for 1.5 h then drain for 30 min to obtain moisture content of 31-33