Compared with atmospheric pressure, a vacuum system is in a negative pressure state, and its absolute pressure is lower than atmospheric pressure. In other words, in a vacuum system, the air content per unit volume is lower than that in the atmosphere. Food processing in such a relatively hypoxic state can reduce or even avoid the harm caused by oxidation, such as fatty acid failure, enzymatic browning, or other oxidative deterioration.
In a vacuum system with a vacuum of 700 mmHg, that is, an absolute pressure of 60 mmHg, the boiling point of water can be calculated using the Clausius-Clapeyron equation, which is about 40oC. Under negative pressure, using oil as a heat transfer medium, the moisture (free water and partially bound water) inside the food will evaporate and spray out, making the tissue a loose and porous structure.
In the vaporization separation operation of aqueous foods, vacuum is closely linked to low temperatures. That is, operation under vacuum. It can effectively avoid a series of problems caused by high temperature processing, such as the deterioration of the polymerization of fried oil, the browning reaction of food itself, and the loss of nutrients.
The ideal mode of vacuum low temperature frying and dehydrating equipment, its basic structural elements include the following four points:
(1) Vacuum equipment with high efficiency, that is, it can process a large amount of three times of steam in a short time and can quickly establish a vacuum condition with a vacuum of not less than 0.092Mpa. High-quality equipment with a secondary vacuum system and an efficient water vapor capture system
(2) Try to have a degreasing device inside the machine, so that degreasing under vacuum conditions can avoid the oil being pressed into the porous structure of food during the process of vacuum returning to normal pressure to ensure that the product has a low oil content
(3) High-tightness vacuum fryer with a large loading capacity (requires an oil storage capacity and heat exchange area that matches the loading capacity, and the temperature rise is fast and stable).
(4) It has automatic control devices for parameters such as frying temperature, frying time, deoiling time, and different methods of frying to avoid the instability of product quality caused by human factors.
First, the scope of application of vacuum fryer:
1. Fruits: such as apple, banana, kiwi, pineapple, strawberry, jackfruit, jujube, green plum and so on.
2. Vegetables: such as carrot, radish, sweet potato, potato, pumpkin, garlic, onion, mushroom, winter melon, okra, lotus root, lotus rice, green beans, toon, houttuynia, asparagus, bamboo shoots, etc.
3, nuts: peanuts, walnuts, badam, various beans.
4. Meat: such as beef, fish fillet, shrimp, crayfish, octopus, small fish, Wuchang fish, etc.
Fruit and vegetable chips are made of fresh fruits and vegetables as the main raw materials, edible vegetable oil as the heating medium, and use advanced technologies such as scientific pre-treatment, low-temperature vacuum (hypoxia) oil bath dehydration (VF), etc. Quickly remove moisture from raw materials such as fruits and vegetables, while forming a uniform sponge-like fluffy structure, to obtain fruits and vegetables with very low water content (below 5%), low oil content, crisp and not greasy, and preserve the original fruits and vegetables to a limited extent Its shape, color, aroma and taste, and rich in vitamins, minerals, fiber and other nutrients, have low sugar, low salt, low fat, low heat and safety, long shelf life and other characteristics. There is no need to add preservatives throughout the product processing.
Composition of vacuum frying equipment
Vacuum oil bath dehydration kettle, oil heating system, oil treatment system, water vapor capture system, cleaning system, vacuum system, pneumatic system, automatic deoiling system, electrical control system.
Fourth, the equipment configuration:
This equipment is a highly integrated vacuum fryer, which can be used by users after connecting to water and electricity.
1. Vacuum fryer, made of food-grade SUS304, with matte finish on the outer surface and polished finish on the inner surface. Equipped with lighting window, observation window, built-in degreasing device, shaft seal parts adopt food-grade seals and vacuum seal.
2, the equipment uses electromagnetic heating, high thermal efficiency, heating temperature can be adjusted.
3. The combination of stainless steel primary filtration system and cardboard fine filtration system is adopted. Improve product quality and oil utilization.
4. The water vapor capture system is made of food-grade SUS304, with a matte finish on the outer surface, and a stainless steel heat exchange tube.
5, the vacuum pump is a water ring vacuum pump, stainless steel material, using a special structure to avoid noise under extreme vacuum conditions.
6. The electrical control system is an automatic control system, using Siemens touch screen and PLC, low-voltage electrical components from Schneider, France, to ensure the reliability of the control, a high degree of automatic control, stepless speed regulation by the inverter for oil removal, and can be free according to different food Choose deoiling revolutions to reduce the breakage of food. Imported sensors are used to ensure accurate control.