There are two ways to preserve vegetables for long periods of time: fresh preservation and dry preservation. The vacuum freeze-drying method combines the advantages of these two methods, and can better preserve various nutrients of vegetables, especially volatile and easily decomposable nutrients, and maintain the original color, aroma and taste of vegetables. Can restore the original form. This method is favored in the international market and is also used in fast food.

With the continuous improvement of consumption, consumers' demand for food and beverage is also constantly improving. Fruit and vegetable chips can be said to be products produced by this trend. Since its launch on the market, it has always been popular with consumers and has been chosen as a natural healthier choice for casual food.
Some people say that dried fruit contains too much additive and is not healthy. In fact, the real dried fruit is a product made of fruit through a boring process. The manufacturing process is neither sugared nor salted, and no fragrance or pigment is involved. This boring process concentrates the sugar, protein, fat and minerals in the fruit. Dietary fiber and some anti-oxidant ingredients and vitamins that are not afraid of heat are also concentrated. Therefore, dried raisins, dried mangoes, dried apricots and other natural fruits can help the body to make up for minerals such as potassium and calcium and dietary fiber, especially for summer sweating.
Most of the fruit and vegetable chips sold on the market today are dry and dry with a dryer. Vitamin C content in fruits and vegetables is extremely rich. Vitamin C is a colorless and odorless flaky crystal, soluble in water and insoluble in organic solvents. It is stable in an acidic environment and can cause oxidation damage in the presence of oxygen, heat, light, and alkaline substances in the air, especially when it is present by oxidase and trace metals such as copper and iron. Oxidase is generally more abundant in vegetables, so there are different degrees of loss in the process of vegetable storage. Although the dryer is boring, the nutrients in it are easily damaged.
The real dried fruit is processed by the air freeze-drying skill. The principle is to use the principle of improvement in the vacuum state of the pre-frozen food, and the moisture in the water is removed from the solid state by the ablation, and then the material is removed. It is boring and can retain the color, taste and nutrients inherent in the food, such as vitamins, carotene, dietary fiber and trace elements. The real dried fruit is bright and colorful, and it is soft and crunchy. It will form a powder when crushed with fingers. It can be restored into fresh fruit by putting it in clear water, with a high nutritional adherence rate of 98%. It is important to note that when purchasing, carefully read the label on the package and select non-fried, natural fruit dried fruit that is not rated with added salt or sugar. Fruit is a kind of food with high added value, and freeze-dried fruit will have a very broad market prospect. Now, the implementation of freeze-dried fruits using freeze-drying machines has encountered bottlenecks. The reasons for this are mainly the following three reasons.
First, the difference between different fruits is relatively large
The variety of fruits is complex. Even for similar fruits, if the environment is different, climate inequality will lead to great differences. Therefore, the skill parameters of the fruit freeze-drying process are difficult to classify and calculate a consistent standard process. For example, different kinds of fruits have different color protection processes due to different enzymes, and the fruit is also very well loaded. Different thicknesses of the plates will result in different quality of the final freeze-dried products, so Different fruits should be selected for specific freeze-drying processes.
Second, the freeze-drying process takes a long time and consumes a lot of energy. Vacuum freezing and boring is considered to be the most expensive and boring method. By vacuum freezing the boring food, the cost is about 5 to 7 times that of hot air and boring, 7 to 8 times that of frozen food, and 7 times that of spray drying. The pre-freezing energy consumption in the process of vacuum freezing and boring only accounts for 4% to 14%, and the total energy consumption of vacuum pump, heating plate and cold trap operation in the boring process accounts for 86% to 96%. Because of the high capital cost of its equipment, the high energy consumption in the production process has caused some manufacturers to be afraid and then limit the practical application and development of freeze-drying skills.
Third, the appropriate skill parameters are more difficult to determine the parameters of the vacuum freeze boring process, have a decisive impact on the quality of freeze-dried fruit. The freeze-drying process consists of pre-freezing, one boring, secondary boring, and storage stages, all of which are proper messy heat and mass transfer processes; and these processes are intimately linked to the nature of the fruit. Therefore, it is necessary to determine a variety of thermophysical properties of fruits, clarify the factors affecting heat and mass transfer in the process of freezing and boring, in order to formulate a robust program, select an optimized freeze-drying control process, and produce high-quality freeze-dried products.
However, the freeze-dried fruit is quickly frozen, vacuum-dehydrated, preserves the original color, aroma, taste, nutrients and the appearance of the original material, and has outstanding rehydration, and does not contain any additives, is an ambition Natural and hygienic high-end food. With the growing food safety problem, the space that followed was beyond fantasy.
 

Freeze-dried spinach

Freeze-dried garlic

Freeze-dried celery

Freeze-dried onion

Freeze-dried carrots and yam