Study On The Technology Of Microwave Vacuum Drying About Stropharia Rugoso-annulata

Stropharia rugoso-annulate is rich in protein, vitamins, minerals and many bioactive substances. The dried product odour is fragrant. It can enhance human body resistance by frequently eating Stropharia rugoso-annulate which was known as "mountain treasure". The traditional drying way of Stropharia rugoso-annulate were mainly solarization and airflow drying., which could make the product dark, rehydration ability bad and odor lack. Microwave vacuum drying technology was applied to Stropharia rugoso-annulate drying in this paper. The microwave vacuum drying characteristics of Stropharia rugoso-annulate was studied, and kinetic models of microwave vacuum drying was established correspondingly. Effects of each factor of microwave vacuum on dried Stropharia rugoso-annulate were studied. Then the optimal drying technology was determined by optimizing drying technology. The project would offer technical guarantee for energy-saving processing and producing dried product of high quality.1. The effects of different microwave power, vacuum degree and loadage on Stropharia rugoso-annulate drying characteristics were studied. The results showed: microwave vacuum drying could obviously reduce the drying time; Stropharia rugoso-annulate microwave vacuum drying course was divided into two stages that were speed-up and speed-down. Constant speed drying was not obvious, accelerating drying stage was short, and speed-down stage was long.The higher microwave power was, the shorter drying time was and the faster precipitation rate was. The higher vacuum degree was, the faster precipitation rate was. Moisture was removed thoroughly, the drying time was short, and product could keep the original form completely. The higher loadage was, the longer the drying time was.2. According to microwave vacuum drying characteristics,kinetic models of microwave vacuum drying for Stropharia rugoso-annulate was established. The model satisfied the Page equation MR = e?rtN, of which r=e-2.7554-0.0104X1-0.0524X2+0.0162X3 and N=1.1251+0.0035 X1 +0.1090X2-0.0021X3. It was proved that predicted date and experimental date were nearly accordant and the model could be used for describing the change of moisture in Stropharia rugoso-annulate during microwave vacuum drying.3. The effects of different factors on SOD, Vitamin C, polysaccharide and rehydration ratio of Stropharia rugoso-annulate were studied. The results indicated: microwave power had the great influence on nutrition of Stropharia rugoso-annulate; the higher microwave power was, the more nutrient was lost and the worse rehydration capacity. The possible reasons were that the damaged extent of cellular structure increased when microwave power increased; the increase of vacuum degree and loadage could keep product nutrients; rehydration capacity was greatest influenced by vacuum degree, the possible reason was that enhancing vacuum degree could make cell keep full to rehydrate quickly. Therefore, vacuum degree could be enhanced and microwave power could be reduced appropriately during processing to keep the nutrients, save time and reduce the production cost.4. Microwave vacuum drying technology optimization for Stropharia rugoso-annulate was studied.the optimal drying technology was obtained when microwave power was 1kW, vacuum degree was -90kPa and loadage was 150g.