Research On The Impact Drying Technology Of Apple Chip Gas Jet

China is the country with largest apple production in the world.Apple（Malus pumila）contains apple polysaccharide,saponin,dietary fiber,mineral substance,thiamine,nicotinic acid,vitamins,essential amino acids and many other nutritional ingredients.It is called the "full range of health fruit." Drying is an effective way to extend the shelf life of an apple,reduce weight and save storage space.However,the existing apple drying methods are mainly fried or hot air dry,fried apple slices of finished oil content is too high,and there are high processing costs,serious loss of nutrition and other shortcomings,and hot dry and relatively dry for a long time,high energy consumption;Therefore it is necessary to seek efficient energy-efficient apple processing methods.Air-impingement jet drying is a technology with high heat and mass exchange efficiency,which can significantly shorten the dry time,save energy and get good dry effect.Therefore,in order to improve the processing quality of apple and improve the energy utilization rate,this paper applied the gas jet impact technology to the drying of apple slices,studies the characteristics of the gas jet impact drying of apple chips,discusses the law of water change during drying,The optimum process parameters of apple jet gas jet impact drying were obtained by using genetic algorithm.Moreover,the changes of peroxidase,polyphenol oxidase and VC in the air impingement drying of apple slices were discussed.In order to promote the innovation of apple slices processing technology,this paper provides a theoretical reference for studying the impact of gas jet drying on apple slices,fully exploiting apple resources and improving agricultural products economic value is of great significance.The main achievements were as follows:1 The process of air-impingement jet drying is slow drying.The effect of airflow temperature and slice thickness was the most obvious effect on the drying characteristics of apple slices,Deff is between（1.590 4～3.068 4）× 10^-10(m² · s^-1),increases with the temperature of the airflow,increases in slice thickness and increases in air velocity.The dry activation energy E_a was 26.8 KJ·mol^-1.The Modified Page model is best fitted to the experimental data in the airflow temperature 50～90 ℃,the slice thickness is 2～6 mm and the airflow velocity is 10～12 m·s^-1.The dynamic model of apple jet gas jet impact drying is:MR=exp{-[（-0.194+0.00092M-0.00641T+0.00264V）t](0.9529-0.00171-0.0038T-0.00471V},where T is the airflow temperature,℃,M is the slice thickness,mm,and V is the flow velocity,m·s^-1.2.Based on the factors of airflow temperature,airflow velocity and thickness,the combination of box-Behnken center design and the genetic algorithm in Matlab7.0 were used to optimize the process of vitamin C content,rehydration ratio and energy consumption.Get a better quality,low energy consumption per unit of apple slices.The effect of airflow temperature,slice thickness and airflow velocity on the rehydration ratio and unit energy consumption of the product was significant.Optimum process parameters:air temperature 62 ℃,slice thickness of 2 mm,wind speed 12 m·s^-1.3.The activities of polyphenol oxidase,peroxidase and vitamin C in the process of apple slices AIJD were decreased with the drying,and the increase of temperature will accelerate the loss rate.The thermal degradation kinetics model of vitamin C and the activation kinetics of peroxidase were studied.The first-order reaction equation was followed all.The half-life t1/2 of the polyphenol oxidase was 5.3～0.96 h,the specified constant was 1,425,452,the passivation activation energy E_a was 43.9383 KJ·mol^-1,the peroxidase half-life t1/2 is 6.7～1 h,the specified constant 3,836,227,passivation activation energy E_a is 47.186 KJ·mol^-1.Vitam in C half-life t1/2 is 6.68～1.5 h,the specified constant 73,130,passivation activation energy E_a 36.199 KJ·mol^-1,heating polyphenol oxidase and vitamin C are prone to degradation,while increasing the temperature increase the rate of degradation.