Studies On Technologies Of Hot-air Combined Microwave Vacuum Drying Of Red Heart Sweet Potatos

Sweet potato is a traditional Chinese cuisine,it is loved by people because of its attractive color,delicious and nutritious,and is also one of the most common"green food".This thesis applied the hot air drying and microwave vacuum drying technologies for the red heart sweet potato from YongTai Fuzhou,studied the drying Mechanisms and dynamic models.And on this basis,optimized the hot air combined with microwave vacuum drying process.Meanwhile,explores the effects of several different drying methods related qualities of red heart sweet potato.1?Rotary air drying Mechanistic studies indicated that the throughout of hot air drying is deceleration phase,drying rate was affected by the hot air temperature,air velocity and loadage.The affect of the loadage was not obvious.The Modified Henderson and Pabis equation could accurately describe the hot air drying process of the red heart sweet potato.2?The microwave vacuum drying process of red heart sweet potato could be characterized three distinct drying rate regions:increasing rate region,constant rate region and falling rate region.While entering the constant rate region,puffing phenomenon appears.The whole process was affected by the microwave power,vacuum degree,Intermittent and loadage.The affect of vacuum degree was not obvious.The Modified Henderson and Pabis equation could accurately describe the microwave vacuum drying process of the red heart sweet potato.3?Choose 4 factors in the hot air combined with microwave vacuum drying process:hot air temperature?conversed moisture content?microwave power and vacuum degree.Then the four factors and four levels of orthogonal test was carried out to inverstigate the optimum method.It was determined as follows:the hot air temperature was 60?,conversed moisture content was 50%,microwave power was 2 kW,vacuum degree was-75 kPa.4?Using hot air drying,microwave drying,microwave vacuum drying,combined drying and vacuum drying joint 5 Ways for red heart sweet potato dried,and compare the drying time of each drying method,the unit energy consumption,color,and the resulting product starch content,total soluble sugar content and carotenoid content.5?Analyze possible hazards in each process of combined drying,established five critical control points:acceptance of the raw fruit,peeling,combined drying,packing and storing-distributing.Then develop a HACCP plan based on this table,propose preventive measures and corrective measures to ensure the quality and safety of products.