Study On Microwave Vacuum Drying Technology Of Camellia Oleifera Seed

Camellia oleifera(Camellia oleifera)is a unique and important woody edible oil species in China.Its cultivation has a long history in China.Hunan Province is one of the main production areas.Camellia oleifera seed drying is one of the processes of camellia oil extraction,which is not only closely related to the storage time and quality of camellia seed,but also affects the quality of camellia oil produced.At present,there are still many deficiencies in several drying methods of Camellia oleifera seed,so it is necessary to enrich the drying methods of Camellia oleifera seed.According to the first and second laws of thermodynamics,the thermodynamic model of microwave vacuum drying of camellia seeds was established,and the steady temperature field in the process of microwave vacuum drying of camellia seeds was simulated.The effects of microwave power,vacuum degree and loading amount on the characteristics of microwave vacuum drying of Camellia oleifera seeds were analyzed by single factor experiment and orthogonal experiment.The optimum technology of microwave vacuum drying of Camellia oleifera seeds was obtained.In order to compare the difference between microwave vacuum drying and other drying methods,the experimental study of hot air drying and microwave intermittent drying was carried out.It was found that the drying characteristics of microwave vacuum drying were better than those of hot air drying and microwave intermittent drying.According to the theoretical simulation analysis and experimental results,the following conclusions are drawn:(1)The thermodynamic model of microwave vacuum drying of camellia seeds was established through thermodynamic analysis of materials and the inner cavity of drying oven in the microwave vacuum drying process of camellia seeds,and the principle and characteristics of microwave vacuum drying of camellia seeds were basically mastered.(2)According to the simulation results of steady-state temperature field of microwave vacuum drying of camellia seeds,there is a clear dividing line between the temperature of camellia seed kernel and shell,which is caused by the low thermal conductivity of camellia seed kernel and shell,and the large thermal contact resistance between kernel and shell.The higher the microwave power,the greater the difference between the internal temperature and the external temperature of camellia oilseeds.(3)The microwave vacuum drying experiment of camellia seeds was carried out by using single factor experimental method and orthogonal experimental method.The effects of microwave power,vacuum degree and loading amount on the drying characteristics of camellia seeds were studied,and the drying characteristic curve of camellia seeds was drawn.The results showed that:a.With the increase of microwave power and the decrease of vacuum degree and load,the drying time of Camellia oleifera seed decreased.Among them,vacuum degree has the most influence on drying rate and energy consumption.B.The microwave vacuum drying rate curve of Camellia oilseeds is divided into accelerated drying stage,constant drying stage and decelerated drying stage.(4)The comparative experiments of hot air drying and microwave intermittent drying of Camellia oleifera seeds were carried out to study the effects of different drying methods on the drying characteristics of Camellia oleifera seeds.It was found that the drying time needed by hot air drying was the longest.The drying rate curve of hot air drying has only accelerated drying stage and decelerated drying stage,and there is no constant drying stage.The drying rate curve of microwave intermittent drying fluctuates greatly.