Nowadays, in order to preserve fruits and vegetables for a long time, people often use dried fruits and vegetables to treat fresh fruits and vegetables.The biggest advantage of fruit and vegetable drying is that the content of water in fruits and vegetables decreases sharply after rapid drying.
Microorganisms cannot survive because they cannot use the water inside fruits and vegetables, and they can effectively inhibit the enzyme activity in fruits and vegetables during drying, so as to ensure the long-term storage of fruits and vegetables.
Microwave drying technology for fruits and vegetables:
Microwave drying equipment for fruits and vegetables uses the strong penetrating power of microwave to penetrate heat into the interior of fruits and vegetables.ntegral heating is formed by simultaneously heating the interior and exterior.
Microwave drying is one of the most advanced drying technologies in recent years.Due to its high thermal efficiency, fast heating speed, uniform heating and high degree of automation, more and more attention has been paid to it.
Advantages of microwave fruits and vegetables drying equipment:
1.The fruits and vegetables dried by microwave drying machine are porous, and their volume density is smaller than that obtained by traditional drying,fluffy and crispy.
2.Microwave drying equipment for fruits and vegetables has better elasticity, it could reduced viscosity, combined with vacuum drying,increased elasticity more significantly.
3.Under the condition that the initial moisture content of apple slices is 37.5%, the microwave drying equipment can dry and puffed apple crisp slices within 4 minutes, and the moisture content of puffed apple crisp slices is 5.66%.
4.The fruits and vegetables dried by microwave drying machine have strong fragrance.
5.The fruits and vegetables dried by microwave drying equipment are closer to the primary colors of fruits and vegetables.
Other drying processes:
1.Air drying at normal pressure
Atmospheric hot air drying is the most traditional way of fruit and vegetable drying. Heat exchange is carried out by means of heat convection and heat conduction.The heat conducting medium is flowing air.
Atmospheric hot air drying technology is easy to operate, with low cost and convenient for maintenance. However, when fruits and vegetables are dried, the heat transfer and mass transfer directions are different, which reduces the drying rate and leads to large energy consumption.
Moreover, the surface of fruits and vegetables dried by hot air is warped due to shrinkage and deformation, serious color difference occurs after fruits and vegetables are dried, a large amount of loss of nutrients, the quality of dry products decreases, and the taste is poor.
2.Vacuum drying technique
The principle of vacuum drying technology is to make fruits and vegetables in a vacuum environment. Through heating and continuous vacuumization, the resulting difference in concentration and pressure will transfer the water inside fruits and vegetables to the surface.The gas with moisture leaves the closed environment with vacuum to achieve the purpose of drying.
The advantage of vacuum drying is that fruits and vegetables can be dried at a lower temperature, so as to achieve the purpose of preserving water. Vacuum drying can avoid oxidation and deterioration of fruits and vegetables, and avoid hardening on the surface of materials.
However, due to technical reasons, the output of vacuum drying is small, and the energy consumption is large, which cannot meet the market’s demand for rapid and large amount of drying.After vacuum drying, fruits and vegetables have better preservation, color and rehydration of nutrients.
Dried fruits and vegetables are a kind of healthy and delicious leisure snacks.However, the import of fruits and vegetables dried products accounts for a large proportion in China.
In view of this situation,it is necessary to further improve and optimize the drying technology of fruits and vegetables, promote the use of large microwave drying equipment, make good use of the inherent advantages of abundant fruit resources in China, seize the market, and enhance the competitiveness.