Study On The Drying Methods To The Drying Characteristics And Quality Of Melon Pieces

Xinjiang melon was used as experimental material in this study, which researched on the effects of drying characteristics and quality of melon pieces by airflow drying (AFD), hot air drying (HD), microwave airflow drying (MAD), microwave airflow+vacuum microwave drying (MA+VMD), airflow+vacuum drying (AF+VD) and vacuum freeze drying (FD). Drying characteristics contained rate of water loss, drying curve, rehydration rate, drying time. Drying quality contained Vc content, total sugar, total acid, color, aroma components, microstructure and texture. And the technology of melon pieces by microwave airflow+vacuum microwave drying (MA+VMD) was in specialized research. The results are as follows: compared with the several drying methods, drying time by MA+VMD was the shortest and drying could finish in3h by this method, followed by was the method MAD. The drying time by FD was the longest18h. With the drying temperature increased, the drying rate of HD and FD increased, but rehydration ratio decreased.Compared drying quality of the melon pieces by these several drying methods, MA+VMD could get high-quality dehydrated melon piece. MA+VMD drying products had a higher ascorbic acid retention(86.17%) drying rate, the puffing(285%), better color, texture and rehydration capacity.Using MA+VMD method to extrude dried melon pieces, the condition of which was28℃and the airflow speed of2m/s. Under this condition the finally moisture content was50%, then using dry vacuum microwave drying to the dry end. The parameters of vacuum microwave drying melon pieces was explored by testing Software Design Expert8.0.3and Box-Behnken central composite experimental design. And regression model of vacuum microwave puffing of melon pieces and the initial moisture content, microwave power and the vacuum degree was established, that was Y=310.40-19.62X1+0.00X2+13.38X3-4.50X1X2-4.75X1X3-12.00X2X3-33.83X12-32.58X22-29.32X32The model was proved to be reliable. The model’s response surface and contour were used to discuss critical factors of vacuum microwave drying melon pieces and their interactions and optimization of process parameters were as follows:microwave power89%, degree of vacuum0.075MPa, initial moisture content of22.5%(w. b.), puffing was287%.