Study On Mechanism And Equipment Of Low Temperature And High-Pressure Infiltration Puffing For Kiwifruit

With the improvement of living standards,more attention is paid to nutritional status,quality,greenness,and natural aspects of food.The concept of diet has changed,and the sensual pleasure of food is more valued.How to make fruits and vegetables meet the high-quality consumption needs of modern people has become one of the important tasks of food science and technology workers.As is known to all,China's total fruit production is very high but most of them are mainly fresh food,and there are always problems such as " low income with good harvests " and "fruits hurting farmers".Therefore,the primary problem of all in our country is how to extend the shelf life of fruits while keeping their certain nutrition.One of the methods is to process fresh fruit into puffed food.Ways to produce puffed food vary while problems come with such as simple nutritional content,high in sugar,fat and salt.In this regard,this paper puts forward a low temperature and high-pressure infiltration puffing technology for the preparation of kiwi crisps,with a view to providing theoretical basis and technical support for the drying of fruit and the development of puffing technology and equipment.This paper explores the mechanism of low temperature and high-pressure infiltration puffing of kiwi,optimizes the process of nitrogen(N2)and carbon dioxide(CO2)as a high-pressure medium,and carries out the design of the low temperature and high-pressure infiltration puffing device of kiwi.Specific research contents are as follows:(1)The infiltration puffing mechanism of kiwifruit at low temperature and high-pressure was investigated.First,N2 was used as a high-pressure medium to conduct experimental research on low temperature and high-pressure infiltration puffing of kiwifruit.Different experimental factors(slice thickness,moisture content after pretreatment,vacuum drying time,pressure or temperature during puffing)on low temperature and high-pressure infiltration puffing of N2 kiwifruit were explored.The ideal N2 low temperature and high-pressure infiltration puffing parameters of kiwifruit were obtained.(2)Experimental research on low temperature and high-pressure infiltration puffing of kiwifruit using CO2 as a high-pressure medium.Different experimental factors(slice thickness,moisture content after pretreatment,vacuum drying time,pressure or temperature during puffing,intake time)were explored through single-factor experiments and response surface interaction analysis.The influence of moisture content after pretreatment,vacuum drying time,pressure during puffing,temperature during puffing,and feeding time on low temperature and high-pressure infiltration puffing of CO2 kiwi was taken into account,and the ideal CO2 low temperature and high-pressure infiltration puffing parameters of kiwi were obtained.In addition,the internal structure of kiwi slices under hot air drying and CO2 low temperature and high-pressure infiltration puffing was analyzed and compared.Experiments suggested that the kiwi crisps prepared by CO2 low temperature and high-pressure infiltration puffing had large cavities and loose structures inside.(3)Given the problems existing in the existing equipment and the optimal process parameters obtained through experiments,a continuous low temperature and high-pressure infiltration puffing equipment is designed.Including puffing tank,a vacuum drying tank and a cooling system.The tank is designed and calculated respectively for the cylinder,head,support,jacket,sight glass,etc.The puffing equipment can realize the continuous production of kiwi crisps by low temperature and high-pressure infiltration puffing.(4)The static analysis of the puffing equipment designed by ANSYS was used.Based on the design of continuous low temperature high-pressure infiltration puffing equipment,use SolidWorks to create a 3-D model,and then use ANSYS to conduct a static analysis of the designed cylinder,tapered head and open-end connection area.The results show that the designed equipment structure meets the production requirements.According to the characteristics of the cylinder and the tapered head,a fatigue analysis is also performed,and the results show that the design is within a safe range.