Analysis of Development Status and Trend of Domestic Food Drying Machinery

Food processing includes many processes such as sorting, crushing, separating, mixing, sterilizing, refrigerating, and drying raw materials, and the drying process is a key link to ensure food quality. Most foods are wet materials that contain a lot of moisture. If the food is too much water, it will cause life activities of the microorganisms and lead to corruption of the food or shorten the shelf life of food, and increase transportation costs. Drying foods can prevent the proliferation of microorganisms in foods, facilitate storage, reduce the volume and weight of foods, and reduce transportation costs. Due to the variety of shapes and types of foods, such as powders, flakes, bars, blocks, slurries, etc., as well as liquids, wet solids, and biological tissues, a series of physical and chemical changes may occur during the drying process of food materials. (such as shrinkage, surface hardening, porosity, looseness, reversible irreversibility), as well as changes in the loss of nutrients, changes in flavor, browning and other changes in the food, thus drying the dryer structure, work characteristics and performance parameters There are different requirements.

Since the 1950s, China has developed and manufactured many drying machines for foods and grains through the introduction and self-research. It has achieved certain results, but development has been repeated and development has been slow. In the early 50's, China imported food series dryers and drying towers (rooms) from the former Soviet Union. Through mapping, it carried out domestic design and manufacturing. Although there are many forms, the basic structure is generally the same. Heating, ventilation, dehumidification and loading facilities, etc. Combine firewood as a heat source and dry or wet heat transfer through the ventilation or blast to dry the material. The product can basically be used for production, but there is uneven heating and baking. Long time, labor intensity and other shortcomings. Its performance and equipment support are also not perfect. It can be said that before the 1980s, food drying in China was largely dependent on natural drying (such as air drying, drying, and drying), and drying equipment in convenience foods, brewing, sugar production, and dairy products was basically in place. blank.

In the 1980s, along with the reform of the rural economic system and the development of township and village enterprises, China's food industry has achieved rapid development and has also promoted the development of food drying machinery. However, the production of food drying machinery is basically a small scale, it cannot form large batches, the technical content is low, there are not many mature models, and the drying process, production capacity, energy types, and measurement and control technologies are still relatively backward. The main method is to dry the food by traditional heating method, that is, rely on heat to heat the material through conduction, heat convection and heat radiation. This drying process from the surface to the inside prolongs the drying time of the food and leads to the loss of nutrients in the food. , and destroyed the original natural taste of food.

In the 1990s, people’s demand for high-grade foods increased, plus the investment and breadth of foreign investment in the food industry in China increased, advanced foreign food drying machinery was continuously introduced into the country, and the development and innovation of food science and technology personnel in China emerged one after another. Many types of food drying machinery, such as air convection drying equipment, drum drying equipment, vacuum drying equipment, pressurized drying equipment and electromagnetic radiation drying equipment. In the late 1990s, China's food drying machinery workers conducted a lot of research on electromagnetic radiation drying equipment. For example, the Tianjin Packaging Food Machinery Research Institute absorbed the most advanced foreign technology and developed the WTJ series of microwave energy drying equipment with a drying speed. Fast, high thermal efficiency, uniform heating, no pollution, and no damage to the nutritional components of foods, can be widely used in food drying. In addition, far-infrared radiation emitted by far-infrared radiating elements is converted into heat energy to dry foods. The equipment is simple, energy is saved, and the drying speed is fast. Especially for the drying of fruits and vegetables; according to the principle of solar energy can be converted into heat, developed a series of solar drying equipment for drying fruits and vegetables and other agricultural and sideline products. At present, the most advanced cryogenic sublimation drying technology in food drying methods, especially the cryogenic sublimation drying equipment that uses the inexpensive steam jet vacuum pump system in China, has also started to be used in food drying in China, such as in meat and seafood. Fruits, vegetables, beverages, condiments, and flavors and fragrances are dried, but there are few mature models, and further improvements are needed in terms of advanced structure, superior performance, high energy efficiency, and cost.