Study On The Technologies Of Combination Of Hot-Air Drying And Microwave-Vacuum Drying For Guava Slices

Guava,the typical fruits originated from South America,is now favored by customers for the fruits’ Fleshy pulp,fragrance,flavor as well as its nutrition and medicinal value.In recent years,the economic value of guava has been improved,and its cultivation scale has also been developing in the direction of industrialization and specialization.However,with the increasing amount of planting and production of guava,the problem of perishable emerged,which has shorten the storage time and seriously hampered the quality and economic value of guava.Hot air-microwave vacuum drying technology is a widely used food drying technology recently,this paper will apply it to the practice of guava drying production.The study of this paper is about sulfur-free color protection process,the hot air drying characteristics and kinetic model of guava fruit slices,the microwave vacuum drying characteristics and dynamic model,the process parameters of the response surface method and the establishment of HACCP system of the production,The main research results of this paper are as follows:1、In order to ensure the guava sensory quality during drying process,the research of non-sulfur color protection process was studied.on the basis of pre-experiment,sodium chloride,calcium chloride,citric acid were choosed as the color protection agent for pre-treatment of drying process.On the basis of single factor test,through the orthogonal test,The best results for the combination were 0.15%citric acid,0.6%NaCl,0.7%CaCl.2、The paper has studied the hot air and microwave vacuum drying characteristics and the dynamic model of guava fruit slices.In the hot air drying stage,it was found that the hot air drying rate of guava fruit slices was affected by material thickness,material loading,hot air wind speed and hot air temperature.There was no obvious speed up and constant speed stage,and the drying rate maintained a decreasing trend.The hot air drying kinetic process is in accordance with the Modified Henderson and Pabis thin layer drying dynamics model,which can be used to describe the change of moisture content with the time of hot air drying of guava fruit pieces.The microwave vacuum drying characteristics and kinetic model of guava fruit slices were studied.It was found that the microwave vacuum drying rate of guava fruit slices was affected by microwave intensity,material loading and absolute pressure of the cavity.As well as the deceleration phase.The microwave drying dynamics of guava fruit slices conforms to the modified Henderson and Pabis thin layer drying dynamics model,which can be used to describe the change of water content in the process of microwave vacuum drying of guava fruit pomegranate fruit.3、In order to further enhance the quality of the combined dried guava fruit slices,the response surface method was selected to optimize the drying process parameters of the hot air-microwave vacuum combined drying process.Considering the color difference,energy consumption,sensory evaluation value and the vitamin C,The optimum heating parameters were as follows:the hot air temperature was 63.20℃,and the Convert moisture content was 48.85%,microwave intensity was 9.67 w/g.With these optimization process parameters,the energy consumption is 1.47 kw/h,the color difference of dry guava fruit slices(ΔL*)is 2.43,sensory evaluation value is 87.88 points,vitamin VC content is 40.27 mg/100 g.4、In order to establish the HACCP system for the processing of guava fruit slices,the hazard analysis of the process parts of guava fruit slices was carried out,and the five key control ways are raw material acceptance,color protection,combined drying,metering and packaging Point,which can provide the technical guidance for the dry guava fruit pieces of product safety and quality control.