Features of microwave heating

The use of microwave heating has a fast heating speed, small heat loss, easy to operate and so on, not only can shorten the process time, improve productivity, reduce costs, but also improve product quality. Compared with the traditional heating method, microwave heating has the following characteristics: the general heating method by virtue of heating the surrounding environment to heat the radiation or through the hot air convection so that the surface of the object is first heated, and then through heat conduction conduction of the object's interior. This method is inefficient and takes a long time to heat.

The most important feature of microwave heating is that microwaves are generated inside the heated object, the heat source from the inside of the object, the heating is uniform, will not cause "outside the scorched inside the uncooked" phenomenon of entrapment, which is conducive to improving product quality, and at the same time, due to the "inside and outside of the simultaneous heating At the same time, due to "simultaneous heating inside and outside" greatly shortens the heating time, high heating efficiency, and is conducive to improving product yield. Microwave heating inertia is very small, can realize the rapid control of temperature rise and fall, is conducive to continuous production amount of automatic control. The microwave power absorbed per unit volume in the medium is proportional to the square of the electric field strength, so that it can be in a very high field strength

under the processing objects in a very short period of time to rise to the required processing temperature. The strong field high temperature can also produce sterilization effect without affecting the quality of the product. Far-infrared heating frequency than the microwave heating frequency is higher, as a matter of fact, the heating efficiency to be better, but in fact, there is also a penetration capacity of the concept. Although far infrared heating has many advantages, the application is also more extensive, but from the penetration of the object, far infrared far less than microwave. What is meant by penetration ability? Penetration ability is the ability of electromagnetic waves to penetrate into the medium, electromagnetic waves from the surface into the medium and its internal propagation, due to the energy is constantly absorbed and can be converted into heat, it is

carrying heat with the depth of the surface of the medium in the form of an exponential attenuation of the distance. Electromagnetic wave penetration depth and wavelength is the same order of magnitude, in addition to larger objects, generally can be done with the surface heating. The wavelength of far infrared heating is very long, poor penetration ability when heating, in the far infrared irradiation, only a thin layer of the object heating, and heat to the interior mainly by conduction, so not only the heating time is long, and easy to cause uneven heating. According to the comparison, microwave heating penetration ability than far-infrared heating is much stronger. (1) Microwave oven cooking food

(2) microwave oven convenience food

(3) microwave oven food containers Microwave vacuum dryer

(1) Advantages

High plant utilization. Production capacity is 3-4 times of the traditional dryer.

- - Fast drying speed and short time.

- - Good product quality

- - Good sanitary conditions

- - Energy saving. Adopting microwave drying can save 20%-25% energy.

(2) Disadvantages

- Large investment and high power consumption (1) Advantages

- Short time

- Small footprint

- Low water loss rate

- Surface is not easy to oxidize

- Not easy to discolour

- Low consumption of clean water

(2) Applications

(2)Application

Meat and its products, aquatic products, fruits and their products, home microwave ovens are used for defrosting frozen foods extremely convenient and fast. (1) mechanism

a, thermal effect: microwave effect on food, food surface and at the same time absorb microwave energy, the temperature rises. Make microorganisms and bacteria protein structure changes, thereby losing biological activity. So that the bacteria die or be seriously disturbed and can not reproduce.

b, non-thermal effects: the microbial chemical process in its life produced a large number of electrons, ions and other charged particles of the biological arrangement of the combination of the state and the law of motion change. In addition, microwaves can also lead to cellular DNA and RNA molecular structure in the hydrogen bond relaxation, fracture and recombination, induced mutations, thus interrupting the normal reproduction ability of cells.

(2) Application

a. It retains more active substances than conventional sterilization methods and is very suitable for drying and sterilizing ginseng, mushrooms, pollen, asparagus and other traditional Chinese medicines and proprietary Chinese medicines.

b, the liquid substance sterilization, such as microwave milk sterilizer, not only the colony number of indicators to meet the requirements, but also to improve the stability of milk.

c, the product of inactivation of enzyme preservation, can overcome the scalding method of a large number of water-soluble nutrients loss. Such as tea manufacturing process of killing. (1) Advantages

- The nutritional value of its products is higher than the traditional method of roasting

- Because it is heated inside and outside at the same time, the time can be reduced to a few minutes

- The internal moisture of the material is rapidly vaporized and migrated outward, forming countless strips of tiny pores, so the product structure is fluffy

- The equipment occupies a small footprint

(2) Disadvantages

Due to the fact that its surface temperature is too low during roasting, it is not enough to produce sufficient Meladic reaction. (1)Principle

Using the internal heating characteristics of microwave, the internal heat of the material is rapidly heated to produce a large amount of steam, a large amount of steam inside the outward rushing, the formation of countless tiny holes, so that the material organization expansion, loose.

(2) Advantages

Compared with the frying and drying type of puffing, it does not destroy the original composition of the material, and it is easy to deteriorate and low heat.