Study On Drying Characteristic And Technology Of Paddy Dried By Far-infrared

For paddy rice to be safely stored for a long term, harvested rice needs to be dried quickly to relatively low moisture content, which is typically done with heated air in commercial production. Since the principle of the heated air drying is based on convectional heat transfer to remove the moisture from the rice, it determines that current drying technology possesses high energy usage and long drying time, which results in low energy and processing efficiencies. Using high temperature air drying can improve drying rate and reduce processing time, but it could significantly deteriorate the milling quality of dried rice. Therefore, the rice industry has been seeking more efficient rice drying technology.Infrared (IR) is the most efficient form of electromagnetic radiation for heat transfer. IR radiation is directly absorbed by the material. IR heating is gaining interest in heating biological products because of its high thermal efficiency and fast heating rate/response time.Drying rice by IR radiation could be one of the possible applications for achieving fast drying and high energy efficiency.This study was aiming at the better far-infrared and hot air drying technology on paddy. Some fundamental theories of the far-infrared technology were investigated and developed.Dying characteristics and mathematic model are drawed on paddy of single factor experiments.The regressive equations of objective functions of paddy are gotten.To be in detail,this study covers the following fields:First, experimental research of far-infrared and hot air drying on the dehydration characteristics of paddyExperiments are made to study the influence of drying temperature,load and initial moisture content on far-infrared and hot air dried paddy.A conclusion is reached that load less affects the speed of dehydration ,but drying temperature and initial moisture content affect significantly.To be more specific,the less the load is,the faster they dehydrate little by little and the less the drying time needs.The higher the drying temperature is, the faster they dehydrate and the drying time decreases significantly. The higher the initial moisture content is,the faster the paddy dehydrate during the prophase,but during the anaphase.it changes slowly.Finally,the Statistical Analysis System processes the date.The mathematics model indicates that the results accord with Page equation, quadratic equation, experiential equation .Second, experimental study on far-infrared drying of paddyExperiments are designed with three factors,which are drying temperature,load and initial moisture content,and five indexes ,which are head rice rate, amylose, Gelcont, HHWD and proteinK. The regressive equations of objective functions are obtained.Through the combination optimization analysis on the three factors respectively,we find when the objective functions are optimized.Then,the effects of the three factors on the indexes are analyzed.The main conclusions are shown as follows: Amylose is correlative with the three factors.In the regressive equation,correlation coefficient R=0.958020, p=0.0292<0.05.With the increase of drying temperature, amylose increases,then reduces.But amylose increases with initial moisture content increase and reduces with load increase;Gelcont is correlative with the three factors.In the regressive equation,correlation coefficient R=0.983995, p=0.0031< 0.01.With the increase of load, gelcont reduces,then increases.But gelcont increases with initial moisture content increase and reduces with drying temperature increase;HHWD is correlative with the three factors.In the regressive equation,correlation coefficient R=0.990809, p=0.0008<0.01.With the increase of load, gelcont reduces,then increases.But gelcont increases with initial moisture content and drying temperature increase;ProteinK is correlative with the three factors.In the regressive equation,correlation coefficient R= 0. 0.987452, p=0.0017<0.01.With the increase of load and drying temperature, proteinK increases.But proteinK reduces with initial moisture content increase;Head rice rate is correlative with the three factors.In the regressive equation,correlation coefficient R=0.980623, p=0.0049<0.01. Head rice rate reduces with the three factors. Third, experimental study on combined far-infrared and hot air drying of paddy Experiments are designed with three factors,which are the temperature of far-infrared drying, the temperature of hot air drying and breaking point of moisture content,and five indexes ,which are head rice rate, amylose. Gelcont > HHWD and proteinK. The regressive equations of objective functions are obtained-Through the combination optimization analysis on the three factors respectively,we find when the objective functions are optimized.Then,the influences of the three factors on the indexes are analyzed afterward.The main conclusions are shown as follows: Amylose is correlative with the three factors.In the regressive equation,correlation coefficient R=0.991674, p=0.0006< 0.01.With the increase of drying temperature, amylose increases,.But amylose reduces with breaking point of moisture content increase;Gelcont is correlative with the three factors.In the regressive equation,correlation coefficient R=0.976978, p=0.0073<0.01.With the increase of drying temperature, gelcont reduces,.But gelcont increases with breaking point of moisture content increase;HHWD is correlative with the three factors.In the regressive equation,correlation coefficient R=0.990974, p=0.0008< 0.01.With the increase of drying temperature, HHWD increases,.But HHWD reduces with breaking point of moisture content increase;ProteinK is correlative with the three factors.In the regressive equation,correlation coefficient R=0.990447, p=0.0009< 0.01.With the increase of drying temperature, proteinK increases.But proteinK reduces with breaking point of moisture content increase;Head rice rate is correlative with the three factors.In the regressive equation,correlation coefficient R=0.950158, p=0.0427<0.05. Head rice rate reduces with the three factors.