Methods of sanitary-hygienic treatment
Cleaning and disinfection can be performed manually with simple tools, such as brushes and rags (manual cleaning), although with an increase in the area of open surfaces that require cleaning and disinfection, special equipment is needed to distribute detergents and / or ensure sufficient mechanical energy. Chemicals can be used in the form of sparse haze haze, foams or gels, and the supply of mechanical energy is provided by high and low pressure hydro nozzles or by hard brushes, driven by water or electricity. These methods are fairly well described, and below we consider only their application in practice.
The use of cleaning methods can be described schematically on the basis of the costs of various energy sources and their ability to work with both low and high (indicated by the dotted line) levels of pollution. For manual cleaning of small items, more mechanical energy can be applied directly where it is needed, and when using tanks for soaking (or cleaning outside the point of use) contact time can be increased and / or more chemical and thermal energy is used.
Disassembled equipment and accessories can be first cleaned of dirt by hand, and then washed and disinfected automatically in tray or tunnel washers. As with soaking in tanks, more chemical and thermal energy can be used to cope with most types of pollution. Placement of tray sinks in high-risk areas for the production of chilled products should be carefully analyzed, since they can form aerosol containing microorganisms, and it can cause airborne contamination of the product.
When hand washing / cleaning large areas, only relatively low temperatures and less chemical energy can be used (due to operator safety), and with an increase in the area requiring cleaning, this method becomes uneconomical with respect to time and labor. Labor costs go up to 75% of the cost of implementing the entire hygiene program, and for most food industry enterprises, such costs for additional staff are prohibitively high. Manual cleaning is economical only with low pollution.
The main difference between aerosol, foam and gel methods is their ability to provide the necessary duration of contact of detergent with contamination and the surface. For all these three methods, it is possible to change the level of expended mechanical energy using the supply of an aqueous cleaning solution under high or low pressure, since the effect of temperature is minimal for cleaning open surfaces.
Fig. 14.2. The use of different energy sources for various cleaning equipment
Aerosol spraying is performed using small tanks with a hand pump, knapsack sprayers, or low-pressure washing installations. By spraying an aerosol, smooth, vertical surfaces are only wetted, and therefore small amounts of fast-flowing detergent can be used, ensuring contact times of 5 min or less. Since this method produces aerosols that can be dangerous if inhaled, only mild chemicals should be used, and therefore aerosol spraying is used only with a small degree of contamination (this method is most common for applying disinfectants to already cleaned surfaces).
Foams can be formed and applied by trapping air in high pressure equipment or by applying compressed air to a low pressure system. The principle of the foam is to form bubbles over the surface that needs cleaning, which then burst and wash the surface with a detergent contained in the bubble-forming film. When foam is formed, it is crucial that the bubbles burst at an appropriate speed: at too high a speed, the contact time will be minimal, and at too low a speed, the surface will not be wetted with fresh detergent.
Gels are thixotropic chemicals that are liquid at high and low concentrations, becoming thick and gelatinous at concentrations of about 5-10%. Gels physically adhere to the surface and are easy to apply using high and low pressure systems or special portable devices with an electric pump.
Foams and gels have a higher viscosity than aerosols, and thus allow the use of more concentrated detergents. They can stay on vertical surfaces for much longer (foams - 10-15 minutes, gels - from 15 min to 1 h and more). Foams and gels can clean higher levels of contamination than aerosols, although in some cases washing the surfaces may require more water (especially in the case of foam). Due to their properties, foams and gels have been recognized by the staff, since chemical substances are better applied and it is easier to identify the missing zones.
Aerosol formation systems (“fogging”) in the production of refrigerated products have traditionally been used to create disinfecting mists, since they reduce the amount of microorganisms in the air and allow them to act on hard-to-reach surfaces in the upper parts of the premises. The effectiveness of treatment with such an aerosol has recently been studied in the UK. When using the appropriate disinfectant method is effective for reducing the number of microorganisms in the air 100-1000 times for 30-60 min. Processing such a “fog” is most effective when using special fogging nozzles operating on compressed air and forming particles of size 10-20 μm. For disinfecting surfaces, this method is effective if enough chemical agents can be applied to the surface. In fig. 14,3 shows the logarithm of the reduction in the number of microorganisms achieved on horizontal, vertical and lower surfaces located in the test room at five levels - from the top near the ceiling (276 cm) to the bottom near
It follows from the above that disinfection is stronger on surfaces located near the floor, and minimal on the lower surfaces near the ceiling. To reduce the risk of breathing, so that the disinfectant mist can settle before the operators return to the production area, after treatment with an aerosol 45-60 min is required.
Disinfectants are removed from surfaces using low pressure hoses with high flow rates, operating at the pressure of water in the water supply system or using pressure washers that operate under high pressure and low flow rates. Pressure washer systems typically operate at a pressure in an 25-25 bar 100-degree nozzle. Mobile or wall installations, as well as centralized loop piping can be used. Nozzles that provide a strong mechanical effect, can be used to clean a wide range of equipment and surfaces, as well as for mixing chemicals. They allow water to penetrate the smallest surface irregularities.
Mechanical brushes are traditional floor brushes, automatic floor cleaning / drying installations, hydraulic drive accessories for high-pressure systems, and small-diameter electric brushes that can be used to clean floors, walls, and other surfaces. When using these methods, the contact time is usually limited (although it can be increased), but the combination of detergent action and the supply of large amounts of mechanical energy allows you to remove most types of pollution. The main limiting factor here is that product processing areas have traditionally been designed without regard to their purpose, although this can be corrected in new and reconstructed areas.
Sanitary equipment should be made of smooth, non-porous, easily washable materials such as stainless steel or plastic. Mild (low carbon) steel or other materials susceptible to corrosion can be used, but they must be properly painted or coated, and the use of wood is unacceptable. The frame should be made of tubular materials or have a box section; it must be closed on both sides and well connected - for example, the seams must be polished and ground, and metal-to-metal joints are unacceptable. Slots and protrusions in which dirt can accumulate should be avoided, threaded connections should be closed or blind nuts should be used. Chemical storage tanks or recovered fluids should be self-draining, have rounded corners and be easy to clean. Housings around the brush heads and rotating brush heads should be easily removable for easy cleaning. Brushes should be with bristles of colored waterproof material (for example, nylon, reinforced in the head of the brush so that there is no place for the retention of dirt). Brushes with a head cast in the form of a single unit can also be used.
Cleaning equipment can become infected with species Listeria and other pathogens, and therefore its use can move contaminants from one zone to another. Therefore, cleaning equipment in a high-risk area should only be used within this area, and after use it should be thoroughly cleaned and (if necessary) disinfected and dried. The ability of the cleaning equipment to spread microbiological contamination in the form of aerosols is described in , where it was shown that all the tested systems, when cleaning test surfaces contaminated with biofilms deposited on them, formed an aerosol containing viable microorganisms.
The degree of surface contamination was divided into ranges - from full coverage to the minimum dangerous level (if the proportion of droplets containing viable microorganisms, the maximum height and distance over which this level of contamination corresponds to the data given in Table 14.4). If we take the average height of the surface that comes into contact with a food product equal to 1 m, then the results show that up to this height, both with the high pressure and low flow method (VDNR), and with the low pressure and high flow method (NDVR a) a significant amount of aerosol is created, and therefore they should not be used in the production process. However, other methods are acceptable for cleaning after the appearance of contamination, since the probability of contamination of the product is low, but when using brushes and dryers for the floor (convenient because cleaning fluid is removed from the floor), if the product is stored on racks close to the floor, care is needed . After production is completed, the VDNR and NDVR methods can be applied without risk, but disinfection of surfaces that come into contact with food should be the last operation performed.
Table 14.4. The maximum height of the spray and getting away
for a number of treatment methods
|cleaning method||Height, cm||Distance, cm|
|High pressure / low flow ejected aerosol||309||700|
|Low pressure / high flow||210||350|
|Set for cleaning and drying the floor||47||80|
|Manual cleaning brushes||24||75|
raking or vacuuming, etc. If possible, contamination on floors and walls should be collected and placed in appropriate waste containers, rather than being drained into the sewer system with hoses.
4. Pre-rinsing. To remove loosely adhering fine dirt, surfaces should be rinsed with cold water at low pressure. Hot water can be used for fatty contaminants, but at too high temperatures, protein coagulation is possible.
5. Cleaning. To remove sticking dirt, various detergents, temperature and supply of mechanical energy are used.
6. The intermediate rinsing. Contaminants separated by cleaning and detergent residues should be removed from surfaces by washing with cold water at low pressure.
7. Disinfection. Chemical disinfectants (or sometimes heat) are used to remove and / or reduce the viability of the remaining microorganisms to a level that is considered non-dangerous. In exceptional circumstances, and only when removing weak contaminants, it may be advisable to combine the 5-7 stages with the use of chemical agents with detergent and bactericidal action (detergents-disinfectants).
8. Subsequent rinsing. The remaining disinfectant must be removed by flushing with cold drinking water at low pressure. Some disinfectants must remain on surfaces until the beginning of the next production period, and therefore their formulation is such that they are surfactant, do not impart flavors to food, and are not toxic.
9. Steps between production cycles. In the period prior to the start of the next production cycle, various actions can be taken to prevent the growth of microorganisms on the surfaces in contact with the product, including the removal of excess water and / or drying equipment. Another option is also possible: removal of the product and personnel from the premises, followed by treatment of the room with an appropriate disinfectant by aerosol.
10.Periodic processing. To achieve an acceptable level of purity of certain equipment or zones, periodic treatment is used, which increases the degree of purification. Such treatment includes weekly acid cleaning, disassembly of equipment at the end of the week, cleaning and disinfection of coolers and sanitary-hygienic processing of surfaces, fittings and equipment at a height above two meters.
To ensure that the tasks are performed and that the cleaning programs are carried out regularly in the food processing area, a clear sequence of sanitary measures should be established. In particular, the procedure of sanitary and hygienic operations determines the sequence in which the surfaces of equipment and the working environment coming into contact with the product (walls, floors, drains, etc.) are sanitized so that after disinfection of these surfaces they are not contaminated again. .
Based on the study of real examples, it was shown that to combat the reproduction of unwanted microorganisms, we can recommend the following sequence of operations for sanitizing the production area of chilled products (this sequence should be implemented so that all surrounding surfaces and equipment in the area are cleaned simultaneously - clean and disinfect one line, and then move on to another and again perform the sequence of operations is impossible, as this only leads to the spread of pollution):
♦ cleaning of production equipment from major pollution;
♦ cleaning of industrial premises surfaces of coarse dirt;
♦ washing the surfaces of the production area (walls usually up to a height of at least 2 m);
♦ washing equipment and solutions in the sewer drain;
♦ cleaning the surfaces (usually, first drains, walls, floors and then);
♦ washing of industrial premise surfaces;
♦ cleaning equipment;
♦ washing equipment;
♦ disinfection of equipment (if necessary washing);
♦ spray treatment (if necessary).