Due to various reasons in the process of processing, storage and transportation, for example, the raw material itself contains a high amount of bacteria, and it is difficult to kill pest eggs and microorganisms in the process of production and processing. Improper storage of raw materials or finished products and pollution in the production process can easily lead to excessive microorganisms and economic losses. Due to the particularity of paprika powder, general heating or chemical sterilization methods are not applicable. Irradiation can effectively control microorganisms and improve the sanitary quality of paprika powder to some extent, but it has the following disadvantages: the location of the radiation source is limited, the irradiation odor or irradiated residue is generated, the special spicy flavor of paprika powder is lost, and the color changes greatly after irradiation. Therefore, it is very important to find appropriate sterilization methods.
Mr. Meng, from yu county, shangqiu county, henan province operating seasoning processing plants, plans to improve the production process and bring samples to the factory to exchange experiments. The water content of chilli powder is about 9%. In order to achieve the best microwave sterilization effect, multiple experiments were arranged and the optimal effect was recorded.
Experimental design table
|EXPNO||Power output（w）||Sterilizing time（s）||The material thickness（mm）|
Microwave power has an important impact on the sterilization effect of chilli powder. With the increase of microwave power, the number of bacterial colonies in chilli powder decreases gradually after sterilization. However, due to the high microwave power (850 w), the phenomenon of burnt chili powder was caused. Therefore, 680,510,340 w was selected as the horizontal values of the orthogonal optimization experiment.
The output power and material thickness are the same, and the sterilization time is different.Compared with the control group, the recorded data showed better bactericidal effect in each group, and with the extension of microwave treatment time, the bactericidal degree of chilli powder gradually increased, and the number of colonies gradually decreased. At the same time, it was observed that the excessive microwave time (150s) had the best bactericidal effect, but some scorched phenomenon appeared in the chilli powder, which may be caused by the low moisture content in the chilli powder, and the excessive heating time caused the evaporation of water and local overheating. Therefore, the sterilization time levels of 60, 90 and 120s were selected in the next optimization test.
Each experiment has good bactericidal effect. When the material thickness is 10,15,20 mm, the microwave sterilization effect of cayenne pepper powder is better. Compared with the non-sterilized cayenne pepper powder, the total number of bacterial colonies can be reduced by 90%, which is mainly because the material thickness has little influence on the microwave sterilization under a certain penetration depth of the microwave field. And because the microwave energy in the microwave oven is certain within the same time, the sterilization effect of 25mm is not good when the material thickness is too high. When the material thickness is 5 mm, the sterilization effect is the best, but the pepper powder appears burnt and the color changes greatly, so the next optimization test chooses the material level of 10,15,20 mm. 510w, sterilization time 120 s, microwave sterilization is the best process condition when the material cover thickness 10 mm.In the experiment, the optimal number of colonies is 2300, and the bactericidal effect is better.
The microwave power of 510W, sterilization time of 120s and material thickness of 10,15 mm were selected for verification test. The experimental results showed that the total number of colonies was 2250 when the material thickness was 10mm and 2960 when the material thickness was 15mm. These two have little difference. However, in terms of the simplicity of operation and cost saving, the best sterilization condition should be selected, which is microwave power 510w, sterilization time 120s and material thickness 15mm.
The mechanism of chilli powder microwave sterilization machine is to use the thermal effect and non-thermal effect of microwave for sterilization. Thermal effect refers to the sterilization at a certain sterilization temperature after microwave heating, while non-thermal effect refers to the denaturation and death of the bacterial cell wall and the active protein contained in the cell fluid under the action of microwave electromagnetic field wave. Microwave sterilization belongs to physical sterilization, sterilization temperature is low, sterilization effect is also good. The whole machine is made of 304 stainless steel, and the conveyor belt is sterilized by automatic assembly line. According to the customer’s request to install a vibration hopper. Microwave equipment can kill escherichia coli and mold.After sterilization, the quality of chili powder and color and taste remain unchanged.