Microwave industrial equipmentteaPrinciples of Sterilization Technology

Microwave sterilization equipment utilizes the combined effects of microwave heating and biological effects. Microwaves affect the potential distribution of bacterial membrane cross-sections, affecting the concentration of positive and negative electrons and ions around the cell membrane, thereby altering its permeability. As a result, bacteria are malnourished, unable to metabolize normally, and their growth and development are hindered, leading to death. From a biochemical perspective, the nucleic acid (RNA) and deoxyribonucleic acid (DNA) that bacteria grow and reproduce normally are coiled macromolecules tightly connected by several hydrogen bonds. Microwaves cause hydrogen bond relaxation, breakage, and recombination, thereby inducing genetic or chromosomal abnormalities, even breakage. Microwave sterilization utilizes electromagnetic and biological effects to kill microorganisms. Practice has proven that using microwave devices has significant advantages in sterilization temperature, sterilization time, product quality maintenance, product shelf life, and energy saving.

Characteristics of Microwave Sterilization

1. Short time and fast speed

Conventional thermal drying sterilization involves transferring heat from the surface of an object to its interior through methods such as heat conduction, convection, or radiation. It often takes a long time for the interior of the object to reach the required dryness and sterilization temperature. The medium is composed of polar and non-polar molecules. Under the action of an electromagnetic field, these polar molecules shift from their original random distribution state to orientation according to the polarity of the electric field. Under the action of high-frequency electromagnetic fields, these orientations constantly change according to the frequency of alternating electromagnetic waves, causing molecular motion and mutual friction to generate heat. At this time, the field energy of the alternating electric field is converted into thermal energy inside the medium, causing the temperature of the medium to continuously rise. Therefore, microwave heating is caused by the loss of electric field energy by the medium material itself and generates heat. So the microwave heating treatment time is greatly shortened, and under a certain power density intensity, satisfactory results can generally be achieved in just a few seconds or minutes.

2. Low temperature drying sterilization to maintain nutritional content

Microwave has a dual bactericidal effect of rapid heating with thermal effect and non thermal effect. Compared with conventional thermal drying and sterilization, it can achieve the desired drying and sterilization effects at relatively low temperatures and in a shorter time. The general sterilization temperature is between 65-70 ℃, 75-80 ℃, or 103-121 ℃, with a duration of 3-8 minutes, and can retain more nutrients and flavors such as color, aroma, taste, and shape. For example, vegetables treated with conventional heat can retain 46-50% of vitamin C, while microwave treatment can achieve 60-90% of vitamin C retention. Pig liver treated with conventional heating has a vitamin A retention value of 58%, while microwave heating can achieve 84%.

3. Conservation oriented machinery

Microwave energy conversion efficiency is high, generally above 70%. Microwaves directly process food, and the heating box itself is not heated, so there is no additional heat loss, so it is energy-saving and can generally save 30-50% of electricity.

4. Uniform and thorough

Conventional thermal drying and sterilization start from the surface of the material and then transfer to the interior of the material through thermal conduction. There is a temperature difference between the inside and outside of the material, resulting in poor drying and sterilization effects. In order to maintain flavor and shorten processing time, the internal temperature is often not sufficient, which affects the drying and sterilization effects. Raising the processing temperature can improve this phenomenon, but it leads to a decrease in the quality of the surface of the item, such as color, aroma, taste, and shape. Microwaves have penetrative properties, acting simultaneously on both the surface and interior, ensuring that both internal and external temperatures reach the required values, resulting in uniform and thorough drying and sterilization.

5. Easy to control, convenient for maintenance, and easy to achieve automated production

Microwave food drying and sterilization equipment is easy to operate, easy to control, without thermal inertia, and can be processed according to different food process specifications, reducing production operators and lowering production costs.

6. Simple equipment and advanced technology

Compared with conventional sterilization, microwave equipment does not require boilers, pipeline systems, coal yards, and transportation vehicles. As long as it has basic water and electricity conditions, there are no special requirements for the factory building, with less investment and quick results.

7. Improve working conditions and save land area

Microwave equipment has no high temperature, helpless heat, does not generate heat itself, and has no thermal radiation. It can greatly improve working conditions, and the equipment structure is compact, saving factory space. It can also be designed and customized according to the actual location of the user.In addition, tea withering is different from sterilization. Although temperature is important, tea withering is the most labor-intensive process, while sterilization is the last step in the production of tea products. Design safe, reasonable, energy-saving, and efficient tea sterilization equipment for tea export enterprises.