The hottest radiation food and sterilization

Radiation food and sterilization

key words: radiation food sterilization

1 mechanism of radiation sterilization

when it comes to nuclear science and technology, people often think of powerful nuclear bombs and the destructive consequences of nuclear explosions. In fact, just as human beings can control electric energy and light energy at will and make them serve human beings, the correct control and use of nuclear energy can benefit mankind in many areas of the national economy. Radiation preservation of food and sterilization, disinfection, is the nuclear industry applied to people's lives in a new technology. The sterilization mechanism of γ - ray produced by radioactive Co-60 can be divided into direct effect and indirect effect. Direct action refers to the direct destruction of RNA, protein, enzyme and other life-related substances of microorganisms by rays, causing the death of microorganisms. Indirect action refers to that the rays first act on the substances around the important molecules of life (mainly water molecules) in the micro organism to produce free radicals, which then act on nucleic acids, proteins and enzymes to kill microorganisms, so as to achieve the purpose of food preservation and sterilization

2 selection of dose

for the articles to be disinfected and sterilized, due to the supplier's negligence of the overall improvement of the functional characteristics of local products, the original infection level is different, the composition state of the articles is different, and the standards of disinfection and sterilization requirements are different, so the irradiation dose should be very different. The most suitable dose that can meet the requirements of health indicators without affecting the original physical and chemical properties of the articles and ensure the economic operation of the irradiation device should be selected. According to the theoretical formula of disinfection and sterilization dose selection: sd=d10lg

sd: sterilization dose, D10: D10 value of indicator bacteria, No: number of contaminated bacteria before sterilization, N: number of viable bacteria after sterilization

in radiation sterilization, microbiological classification and identification of the types of contaminated microorganisms are not required. The task of microbiological identification of so many microorganisms is very arduous. And for those microorganisms with weak radiation resistance, it is not important in irradiation sterilization. Therefore, when considering the types of contaminating microorganisms, it is only necessary to measure the D10 value of anti radiation bacteria, and also take them as indicators of sterilization effect. Bacillus pumilus E601 is generally used as the indicator bacterium in the world

3 determination of d10 value

determination method of d10 value, D10 value refers to the radiation dose required to kill 90% of microorganisms. The most common method is to mark the D10 value with the survival curve

Table 1 microbial test results of bacteria slices after irradiation

dose (kGy)

number of viable bacteria

lg number of viable bacteria

0

5.7 × 106

6.76

1.74

1.9 × 106

6.27

3.21

1.8 × 105

even considering the $% $7 maximum energy-saving effect brought by setting the accumulator

5.25

6.23

3.9 × 103

3.59

11.51

5

0.70

prepare bacterial tablets with the same number of bacteria, Bacillus pumilus E601 5.7 × 106 pieces/piece. These bacteria were used to receive different radiation doses, and the radiation dose was measured by ferrous sulfate chemical dose. Count the viable bacteria (pouring method), and carry out microbial detection on the irradiated bacteria. The results are shown in Table 1

the horizontal axis is the auxiliary irradiation dose, and the vertical axis is the logarithm of the number of viable bacteria, and the survival curve is drawn

the dose value corresponding to the difference of one unit in the logarithm of the number of viable bacteria in the survival curve is D10. It is known that the D10 value of Bacillus pumilus E601 is 1.75kgy. According to the number of viable bacteria after sterilization required by different articles, the radiation dose can be determined by giving the number of bacteria contaminated by articles before irradiation. If the type of microbial pollution of the manufacturer's products and their resistance to radiation are measured, the minimum radiation dose is relatively easy to determine, otherwise, the dose should be increased, and the microbial pollution level should be taken into account. At present, although civilized production is very important, this alone cannot guarantee the hygienic quality of food, including refrigerated and frozen poultry, pork and beef and mutton, some seafood and condiments. These foods can also transfer microorganisms and pathogenic microorganisms to other foods. In food processing, if the electronic universal testing machine needs to be transported, especially in international trade, there are strict requirements for the microbial indicators of some foods. It is particularly important that there should be no pathogenic microorganisms in most foods, such as Salmonella, Staphylococcus aureus and Escherichia coli. The D10 values of common pathogenic bacteria in food are Staphylococcus aureus 0.3kgy, Salmonella 0.25kgy and Escherichia coli 0.34kgy, respectively

4 characteristics of radiation sterilization

compared with traditional methods, the advantages of radiation treatment of food are summarized as follows: it can eliminate microorganisms, prevent pests and diseases, and improve quality and sanitary conditions; Extend the storage time of food and agricultural products, and some irradiated foods can remain fresh for months or years even if they are not frozen; Ray penetration is strong, and it can pass through heavy packaging, so it can kill work without opening the packaging; Radiation treatment does not require heating, so the food disinfected by radiation is almost no different from fresh food in appearance and quality; Radiation treatment will not leave any residue, which has great advantages compared with pesticide fumigation; The operation of radiation food is extremely safe and efficient

according to the decision of the Joint Expert Committee on the health and safety of supplementary food organized by the United Nations Food and Agriculture Organization, the World Health Organization and the International Atomic Energy Agency in 1980, any food irradiated within the dose of 1 megarads will not cause any toxicological harm. According to the large number of health and safety experiments in this study, supplementary food is safe and edible, and will not cause nutritional and microbiological problems. The number of countries that process certain kinds of food with supplementary lighting is increasing, and the number of food processing is also increasing. Supported by a large amount of scientific evidence about its economic and health safety and benefits, this technology is moving forward

Chinese Journal of Microbiology

maxiaomei Chai guangsecretary author unit: Dalian Institute of Applied Technology of nuclear industry 116032