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With the further development of food microwave processing equipment, microwave ovens and industrial microwave ovens, the pace of social life has further accelerated, people's demand for convenience foods has become more and more large, and microwave foods and microwave processed foods have developed rapidly. Therefore, microwave energy equipment has been widely used in the domestic food industry to achieve the purpose of food drying, sterilization, preservation, and puffing; especially in the process of food research and development of new products, bringing convenience, improving research efficiency, shortening the research cycle, and accelerating the turnover of funds. Increased financial resources and achieved high economic returns. Microwave energy application has been adopted by many domestic food, pharmaceutical, and chemical companies, expanding the application field, and pushing products to the international market, occupying many markets and achieving great results.
First, China's microwave energy applications have been successfully applied in industrial, agricultural, scientific research, medical and other aspects. There are two main types of applications in terms of mechanism:
1, using its thermal effects, such as heating and drying, mainly food heating, cooking, baking, blanching, boiled white, drying, heating and drying of industrial products, dehydration and drying of agricultural and sideline products, pre-baking and sintering of ceramic industry , rubber heating vulcanization, grease refining, printing and dyeing pre-fixing, printing glazing and so on.
2. Use its non-thermal effects, such as alcoholization and ripening of liquor; sterilization of food and medicine; suspension of fermentation, quarantine, breeding, promotion of chemical reactions, microwave sterilization, etc. Microwaves also have different understandings of their thermal and non-thermal effects in medical applications.
It can be seen that the field of microwave applications is very broad, but it is not easy to really use it. We must fully understand its superiority and limitations, in order to be effective in its use. For this we come to know its superiority.
1. Energy-saving, because the water-containing articles are easy to absorb microwaves and generate heat, the microwaves directly act on the materials, so there is no additional heat loss, and the air in the furnace concentrates on the corresponding containers without heating, so the thermal efficiency is extremely high. The production environment is also obviously improved. Compared with far-infrared heating, it can save 30% of electricity. The equipment can be used immediately, without thermal inertia, and the operation is flexible and convenient. Therefore, instant heating and stop heating reflect the advantages of energy saving and easy control.
2, selective heating, because water molecules are best for microwave absorption, so the part with high water content absorbs more microwave power than the part with lower water content. This is the characteristic of selective heating. Heat evenly and evenly.
3, the characteristics of microwave sterilization: the effect of microwave sterilization is good. The microwave test results of various strains showed that the microwave sterilization temperature value was lower than the conventional method. The microwave food sterilization test also confirmed this conclusion. The sterilization temperature of the conventional method is 120 to 140 ° C, and the time is about one hour. The temperature of microwave sterilization is 70~105 °C, and the time is about 90~180 seconds.
The effect of microwave sterilization is generally caused by two factors: thermal effect and non-thermal effect. However, the sterilization effect cannot be seen without reaching a certain temperature. Microwave sterilization, both internal and external heating, rapid temperature rise, speed up the sterilization. It is divided into three stages, the first stage, which is to rapidly heat up and reach the predetermined sterilization temperature. At this time, a stronger uniform energy density should be adopted; the second stage is a heat preservation process, so that the temperature of the sterilizing material is in a temperature-balanced process, and the sterilization process is perfected, and the power density is low in this stage; the third stage is a cooling process or Forced cooling process. The sterilization temperature and sterilization time are also different due to different contaminated strains. The sterilization temperature is higher than 100 ° C and must be carried out under high pressure conditions.
Due to the short time of microwave sterilization, it is used for food sterilization, which less damages the nutrients of food and improves the quality of food. Sometimes microwave sterilization and food technology combine to maintain the flavor of the original food and to sterilize more thoroughly than traditional processed food methods. The combination of microwave food sterilization and packaging technology can extend the shelf life to more than three months. The mass production of packaged foods is expected to greatly reduce the amount of household labor. Microwave sterilization method can be used in many fields, such as food, Chinese patent medicine, biological products, Chinese herbal medicines, soy sauce, beverages, corrugated paper, mildew, fruit tree surface lesion treatment and so on.
Second, the principles that must be mastered in the application of microwave energy technology
Although microwave energy can be effectively utilized in various fields, it must be done with caution in order to be successful. The following discussion is about the issues that should be addressed when promoting the application of this new technology.
1. It is necessary to fully understand the physical and chemical properties of the material to be treated in the microwave electromagnetic field, so as to make full use of the advantageous characteristics of the microwave treatment.
2. For economic and social benefits, it must be fully estimated.
The application of microwave technology to transform traditional technologies must pay attention to the improvement of economic benefits. The failure of many early projects is often not a technical problem, but the economic benefits are not good enough. Microwave energy application equipment is a high-tech product. Through nearly two decades of efforts, the development and production level of microwave energy application equipment in China has been greatly improved, optimizing design, improving quality, reducing costs, improving automation, and providing after-sales service. As a result, users of microwave energy application devices have been accelerating in recent years.
Users should give priority to the benefits of using microwave energy, which can bring about the improvement of product quality, how much energy can be saved, and how much output can be increased. In theory, microwave energy per kilowatt hour can vaporize 1.39 kilograms of water. The actual effect is 1.1 kg/kWh due to factors such as line loss and cavity efficiency.
The user can estimate the required microwave power based on the difference between the initial and final moisture content of the material to be treated and the production requirements. The initial cost is estimated based on the investment cost of the microwave equipment to calculate economic benefits. In most cases, the direct benefit is obvious because of the outstanding energy-saving effect after applying microwave. In some cases, the direct economic benefits are not obvious, and even increase the cost. For example, the microwave is used to sterilize the food. Because of the increase of a process, the cost seems to increase. However, the overall benefit is still good because the shelf life is reduced and the loss of goods is reduced. And the social benefits that bring benefits to people's health are even more commendable.
3. Equipment manufacturers and users must work together to make the improvement of equipment performance and product technology adjustments in order to achieve success. |