Freeze-dried dried fruit is dried fruit made by freeze dry candy machine. Fruits and vegetables provide people with nutrients such as vitamins. In order to prolong the shelf life of these foods, people have developed, sun-dried, dried, pickled, and cooked and made into canned fruits, but things like vitamins are , the ability to withstand high temperature is really poor, once it encounters high temperature, it will suffer serious losses. When there is a need, there is creation, so people full of wisdom have developed low-temperature processing technology and working principle of freeze dryer. Therefore, freeze-drying machines are also recognized by more and more people, and the application of freeze-drying machines is becoming more and more extensive soup.
How are freeze-dried dried fruits made?
According to the phase equilibrium theory in thermodynamics, the temperature of the triple point of water (the coexistence of vapor, liquid and solid) is 0.0098°C, and the triple point pressure is 609.3pa (4·57mm/mg). During the phase transition of water, When the pressure is lower than the triple point pressure, solid ice can be directly transformed into gaseous water vapor, that is, ice crystal sublimation.
The principle of fruit freeze-drying is to freeze fresh food containing a lot of water in advance, so that the free water in the fresh food is crystallized and frozen into a solid, and then the ice crystals in the food are sublimated under high vacuum conditions, and the food is removed after the ice crystals sublime. The middle part absorbs water, and finally a dry product with a residual water content of about 1-4% is obtained, that is, freeze-dried food. Equipment that processes freeze-dried food is also known as a food freeze dryer.
What are the characteristics of food freeze-drying technology?
In the process of drying food, the temperature must be controlled within the range of -40°C to +55°C. At the same time, the surrounding environment must be in a high vacuum state during the processing. In food processing that is highly sensitive and prone to oxidation problems, it preserves the food's own taste and protects the nutrients of the food.
Keep the original shape of the material
After drying, the product will not lose its original skeleton structure, and can maintain the original shape of the material to the greatest extent.
Freshness is guaranteed
Once again, the food processed by freeze-drying technology has a porous structure, so it has good rehydration, and at the same time, it dissolves in water very quickly. In this case, the freshness of the food is also well guaranteed. .
Nutrients are not lost
In the process of sublimation, the water-soluble substances can be precipitated smoothly, which also effectively prevents the loss of nutrients and inorganic salts due to the transfer of water inside the material to the surface of the material by other drying methods, which can keep the material to the greatest extent possible. nutrient content.
Product quality is improved
The last point is that freeze-dried food is packaged in vacuum or nitrogen flushing in the production process, and can also be stored in the dark, so the shelf life of such substances can be as long as five years. Compared with quick-frozen food, No need for transportation and storage, this processing method can be very effective in improving the quality of the product.
Is freeze-dried dried fruit healthy?
Most people think that freeze-dried fruit is unhealthy, but they are wrong. Freeze-dried fruit is nutritious and harmless. Because freeze-dried fruit adopts the vacuum freeze-drying method of mini freeze dryer machine
, the water in the fruit is frozen in advance, and then the frozen water in the fruit is sublimated in a vacuum environment to obtain freeze-dried fruit. Compared with the traditional high-temperature heating, the nutrient loss of fruit chips is relatively small, the nutritional value is much higher, and the original nutrients of the fruit are basically retained.
In short, the water in the fruit is pumped in a low temperature environment to retain its original nutrition. Not only that, but freeze-dried fruit is storable, lightweight and easy to carry. Whether it is home travel or spaceflight (most of astronauts in space are freeze-dried products) freeze-dried is the best food, which can satisfy your hunger and satisfy your stomach. It can also supplement nutrition.
What is the difference between freeze-dried fruit and dried fruit?
Freeze-drying and drying are two processing techniques
Freeze-drying technology: Also known as low-temperature vacuum drying technology, it uses a special machine to quickly dehydrate the food at a low temperature of minus 40 degrees Celsius in a vacuum environment. , and then in a vacuum environment, the solid ice directly sublimates into a gaseous state. The food produced in this way has a relatively crisp taste and low moisture content, which can well retain the original color, taste and nutritional content of the product.
Drying technology: Drying does not require vacuum or low temperature. Generally, it is in a relatively ventilated place with a high temperature to evaporate the water in the food. volatilize out. The drying technology results in shrinkage and deformation of the product, deepening of the color, and large loss of nutrients at high temperature.
Freeze-dried fruit is sublimated and dehydrated, and the moisture of the fruit is directly converted from the frozen state to water vapor, which has less impact on the plant frame (cell wall) than drying. It will shrink a little when dried
Freeze-dried fruit is processed in a vacuum environment, so the oxidation reaction is less, and the color is more vivid
The oxidation reaction of dried fruit is more carried out, so the color is darker.
Nutrient retention comparison:
The full name of freeze-drying is vacuum freeze-drying, which is frozen at more than minus 40 degrees, and then sublimated and dehydrated. The vacuum environment reduces the oxidation of the fruit, and preserves the nutrients in the fruit as high as 95%.
The temperature of the dried fruit is above 100 degrees, the high temperature damages the vitamins very high, and the vitamin or loss rate is higher.
The dehydration rate of freeze-dried is as high as 95%, and most of them are crunchy. Freeze-dried fruit is biologically active, and it will absorb moisture in the air and become soft when exposed to the air.
Drying mainly depends on the dehydration situation. Less dehydration is soft, and more dehydration is brittle.