Studies On Technology Of Microwave Vacuum Drying For Pumpkin Slices And Packaging And Storage Of Dried Pumpkin Slices

Pumpkin(Cucurbita moschata Duch.)is a kind of vegetable with rich nutrition,high healthy and medical values,but fresh pumpkin is perishable and inconvenient transportation,so dried is a good choice to solve these problems.Compared the drying time and energy consumption of the drying methods and the quality of products,technology of microwave vacuum drying is suitable for the processing of fresh pumpkin dried.The mass transfer model,optimized the processing of pumpkin by microwave vacuum drying and the characteristics of dried pumpkin slices during storage were studied.Finally,HACCP system was established in order to provide complete technical support for the industrial production of microwave vacuum dried pumpkin slices.Fresh pumpkin was dried by hot air drying(60,70,80?),vacuum drying(60,70,80?),microwave drying,microwave vacuum drying and freeze drying.Their drying time,energy consumption,carotenoids content,color,rehydration,porosity and other quality parameters were analysed comparatively.The results showed that the products of freeze drying had the best quality,but the highest drying energy consumption.Hot air drying and vacuum drying need longer time and their products had poor quality.The products of microwave drying scorched.The quality of microwave vacuum drying products was just below freeze drying,and its drying time and energy consumption is far less than the freeze drying.Taken together,microwave vacuum drying is more suitable for pumpkin dried.The microwave vacuum drying characteristics of pumpkin slices under differentmicrowave power density levels,chamber pressure and slice thickness were investigated,and the moisture content of pumpkin in microwave vacuum drying could be predicted by establishing the mathematical model.The results showed that the drying time and rate were noticeably influenced by microwave power level,while not noticeably influenced by chamber pressure and slice thickness.According to the statistical parameters as the correlation coefficient,square sum of error and root mean square error,Page model was suitable for describing and predicting the moisture ratio change kinetics of pumpkin microwave vacuum drying process.The research can provide technical basis for the industrial of pumpkin drying by microwave vacuum technology.In order to product high-quality pumpkin slices with low energy consumption,optimization of drying process parameters for pumpkin microwave vacuum drying using the response surface method based on single factor tests.The mathematical model of consumption,sensory quality and carotenoids content were established.In order to study the quality variation of dried pumpkin slice during storage,fresh pumpkin slices were microwave vacuum dried and packed.The changes of moisture content,water activity,color and carotenoids content during the 5-mounth storage period were measured for deciding the effects of packaging and temperature(0,20,35?)on quality.The kinetics of color(a*,b*values)loss,carotenoids degradation of dried pumpkin slice and the relationship between them were invetisgated.By analysing potential hazards in the drying processing of pumpkin,critical control points were determined.Limitation values for critical control points,monitoring procedures and corrective measures were set up to improve the level of safety and quality of dried pumpkin.