A basic knowledge of disinfection
1, what is called disinfection
Disinfection refers to the removal or killing of pathogenic microorganisms and other harmful micro-organisms in the external environment, but it is not required to remove and kill all the micro-organisms, the significance of which is relative, and only required to make the micro-organisms reduce to the extent that they can no longer cause disease. The concept of killing all microorganisms is called "sterilization", which is more demanding than disinfection. Catering units are mainly to solve the problem of disinfection, only the central kitchen and collective distribution of meal units in individual places involving sterilization.
2, the significance of disinfection
Pathogenic microorganisms discharged from the source of infection, can survive in nature for a certain period of time. The length of its survival time with the type and environment, short of a few hours, long up to a few days to several years, therefore, disinfection is an important part of food safety work in the catering unit. Through the implementation of disinfection measures, can kill or eliminate food utensils and the working environment of pathogenic microorganisms, so it is very positive and important means of preventing disease from entering by mouth.
3, factors affecting the effect of disinfection
The effect of disinfection is good or bad, not only with the choice of disinfection methods, but also with the disinfection process factors. These factors are mainly the following six points. ① Intensity (or concentration)
Intensity in thermal disinfection refers to the temperature, in ultraviolet disinfection refers to the irradiation intensity (power), and in chemical disinfection refers to the concentration. The higher the intensity (or concentration), the better the efficiency is generally. But alcohol disinfection is an exception (75% alcohol disinfection is the best,
concentration is too low or too high can not achieve the disinfection effect).
② time
That is, the disinfection time. The longer the time, the less the ability of microorganisms to survive relatively speaking. ③ degree of microbial contamination
The degree of microbial contamination is serious, the disinfection time is prolonged, and the amount of drugs should be increased. This is due to the overlap of microorganisms with each other, strengthening the mechanical protection effect.
④ Temperature
In addition to thermal disinfection completely dependent on the temperature used to disinfect, other methods, under the same conditions of dosage, time, etc., the killing effect is generally with the increase in temperature. ⑤ Humidity
The relative humidity of the air has a significant effect on fumigation and disinfection. When using formalin or ethylene oxide and peroxyacetic acid fumigation, the temperature is too high or too low. When using lime bleach powder to spread directly on the ground, it is hoped that the humidity is high, in order to facilitate the powder deliquescence and play a role. And ultraviolet disinfection, such as encountering high humidity instead of reducing its penetration, which in turn affects the disinfection effect.
⑥ pH
The new clean and destroy the alkaline environment works better, charcoal in the acidic environment works better.
Second, the commonly used disinfection methods and the scope of use
1, physical disinfection method
physical factors to kill or remove pathogenic microorganisms and other harmful microorganisms, known as physical disinfection method. Here we mainly introduce thermal disinfection (which includes boiling disinfection, circulation
steam disinfection, autoclaving, dry hot air sterilization, etc.) and radiation disinfection (here mainly refers to infrared and ultraviolet disinfection )
① boiling disinfection. Its heat conduction is mainly realized by convection of water. This method, the temperature is up to 100 degrees Celsius, but kill bacterial propagules generally a few minutes. Operation is simple, economical and practical, and the effect is reliable. Applicable to all kinds of catering units, with iron or aluminum pot can be. Note: Sterilization time should be counted from the beginning of water boiling. It usually takes 10 to 30 minutes. The whole sterilization process should be kept boiling. Continuous boiling, do not add new items, dishes should be placed vertically to facilitate convection of boiling water, items should not be placed too much, generally no more than 3/4 of the container.
② circulation steam sterilization. Common equipment has a steam sterilizer, steam dishwasher and so on. This method is suitable for all types of catering units. Precautions are basically the same as the boiling method.
③ High-pressure steam sterilization. This disinfection method is commonly used in the sterilization of medical equipment, catering units are rarely used, do not do a detailed description.
④ dry hot air sterilization. Commonly used in laboratory sterilization, not to be described in detail. ⑤ Ultraviolet radiation sterilization. The method due to poor penetration, it is generally only used for air, water and object surface disinfection, catering units commonly used in the special room disinfection. Disinfection of object surfaces, irradiation of the surface of the ultraviolet intensity should not be less than 70UM/CM2, irradiation time should not be less than 25 minutes, the disinfection of indoor air, should be used indoors hanging ultraviolet when the power of the lamp on average not less than 1.5W per square, the general indoor irradiation, ventilation for 1 hour after every 40-120 minutes to reduce the ozone content in the air.
⑥ infrared disinfection: the use of 0.77 ~ 1000 micron wavelength electromagnetic waves generated by the thermal effect of disinfection. Apply to the object surface disinfection, the proximity of the light source and the sterilization temperature has
off, 20 cm at 175 ℃, 50 cm at 125 ℃, 100 cm at 55 ℃. Temperature rise quickly and slowly, high and low with the strength of the light source. Different colors of objects on the infrared absorption rate is different, black is 87%, gray is 75%, green is 73%, red is 64%, yellow is 50%, white is 46%.
2 chemical disinfection
Disinfection with chemical disinfectants, known as chemical disinfection, because of the residue and environmental pollution involved, generally not recommended as a common method of disinfection of food and beverage utensils, can be applied to the staff of the hand disinfection and temporary emergency disinfection. Chemical disinfection uses solution soaking, wiping or spraying.
① Alcohol
70% to 75% alcohol used for disinfection, too high a concentration of alcohol will form a protective film on the surface of the bacteria, preventing it from entering the body of the bacteria, and it is difficult to kill the bacteria completely. If the concentration of alcohol is too low, although it can enter the bacteria, but can not solidify the proteins in its body, the same can not completely kill the bacteria. 75% alcohol disinfection effect is the best. 75% alcohol is commonly used in medical disinfection, catering unit staff hand disinfection is also commonly used, generally take the way of soaking and wiping. It is important to note that alcohol is extremely flammable, remember to use at high temperatures and open flames.
② Chlorine disinfectant
Chlorine disinfectant has a broad-spectrum bactericidal, rapid killing of Escherichia coli, Staphylococcus aureus, Bacillus subtilis, black variegated spores. Destroy hepatitis B surface antigen. Remove dirt strong force, non-toxic and non-irritant, low cost of use, using method: the original liquid and water in a certain proportion configured into an application solution. Mode: soaking, wiping, spraying and so on.
Three, catering unit disinfection method analysis
(a) the disinfection method of catering utensils.
Conditional catering units preferred circulation steam disinfection, such as the provision of steam school canteens and large and medium-sized catering units, this method of disinfection is reliable, disinfection time is relatively short, the disadvantage is that there must be a supply of steam, the operation of the steam is easy to diffuse the indoor temperature is relatively high; the second choice of dishwashers and other semi-automatic or automatic cleaning and disinfection equipment, cleaning and disinfection of a high efficiency, the disadvantage of the equipment is more expensive, the effect of disinfection Not as stable as steam sterilization and boiling disinfection. Boiling disinfection, cheap hardware and reliable results, but because of the cooling and heating time is longer, need to be equipped with certain auxiliary tools and personnel. The choice of disinfection cabinet is generally as far as possible to choose a large-capacity electric steam disinfection cabinet, the second choice of far-infrared disinfection cabinet.
(ii) special room disinfection method.
Special room environment and operating table, wall, floor disinfection is generally taken with the function of disinfection of medical ultraviolet lamps (wavelength 240-275nm, of which 253.7nm disinfection effect is the best), must not be confused with fly-inducing ultraviolet lamps (no disinfection effect); ozone can be used as an alternative to disinfection of the special room, but because of the disinfection effect of the difficult to assess and need to be more layout, disinfection, disinfection and decomposition takes a period of time, do not recommend the use of ozone. After the decomposition takes a period of time, do not recommend the use.
(c) Staff hand disinfection methods.
Staff hand disinfection first medical alcohol soak or wipe, because the kitchen has more open fire, pure liquid medical alcohol flammable and explosive, so it is recommended to wipe wipe clean and other wiping disinfection methods; secondly, you can use a medical class of disinfection products, such as medical disinfection class hand sanitizer, etc.; you can also use sterile disposable gloves, but pay attention to the difference between the
Ordinary disposable gloves. The first thing you need to do is to use the same gloves as you would if you were a professional.
(d) Temporary and emergency disinfection methods.
When food safety accidents or the need for emergency disinfection and common disinfection methods can not be completed in a timely manner, chemical disinfection can be used, commonly used chlorine disinfectant disinfection.
Fourth, tableware disinfection general procedure
Tableware disinfection general process for a scrape, two wash, three punch, four disinfection, five cleaning. A scrape, that is, the remaining food residues on the tableware clean. The second wash, the use of detergents will be clean dishes.
Three rinse, the use of clean dishes with water rinse, wash away the residual detergent. Four disinfection, physical or chemical methods of disinfection.
Five cleaning, disinfected tableware in a timely manner in the cleaning cabinet, to be stored closed to prevent recontamination. After 72 hours of disinfection unused tableware need to be re-sterilized.