Production of many chilled products usually include some element of group processing or layout (or both).
The equipment used for such operations is mainly of an open type, that is, it cannot be cleaned by an in-place cleaning (C / P), and its design must meet the highest hygienic standards. Designing equipment to meet sanitary requirements has three main advantages:
- quality - when properly designed, the product remains in the main stream, which eliminates product delays in equipment, where it can deteriorate and affect the overall quality of the product when combined with the main stream (for example, in the production of flavors, one batch cannot taste the next);
- Harmlessness (safety) - proper design prevents contamination of the product with substances that would adversely affect the consumer's health. Such contamination can be microbiological (for example, pathogenic microorganisms), chemical (for example, lubricants, detergents) and physical (for example, glass);
- efficiency - proper design reduces the time required to clean a piece of equipment. During equipment service time, this reduction in cleaning time is quite significant, so equipment designed to meet hygienic requirements and initially more expensive (compared to similarly functioning poorly designed equipment) will be more cost-effective in the long run. In addition, saving time during cleaning / washing can help increase productivity.
On the hygienic aspects of the design published relatively few scientific papers. [1,15, 17,27,29] is applicable to the production of refrigerated products. In Europe and the United States there are a number of organizations (EHEDG, 3-A Standards, NSF — National Sanitation Foundation), whose work is aimed at achieving a consistent approach to the design taking into account sanitary requirements, and the use of the guidelines of these organizations can have almost regulatory status. It should be noted that in Europe, design guidelines for hygienic requirements are usually more general than American (more prescriptive) requirements.
14 June 1989 was published by the EU Directive (89 / 392 / EEC) on the approximation of the laws of individual states, which includes a small section on hygiene requirements for equipment. It states that equipment intended for the preparation and processing of food products should be designed and manufactured so as to avoid risks to the health of consumers. Seven sanitary and hygienic rules have been identified concerning:
- materials in contact with food;
- surface cleanliness;
- preference welding or connection using fasteners;
- design, contributing to the cleanability and disinfection of equipment;
- good drainage surface;
- prevent "dead" spaces that cannot be cleaned;
- design to prevent contamination of the product with auxiliary substances (such as lubricants).
This Directive requires all equipment sold in the EU to comply with these basic requirements and be marked with compliance with the prescribed standards (CE mark).
Appeared after this Directive European standard EN 1672-2 “Food processing equipment: safety and hygiene requirements. Basic concepts. Part 2: Hygiene Requirements ” is adopted to further clarify the hygienic rules set forth in 89 / 392 / ЕЕС. In addition, a number of specific standards are being prepared for bakery and pasta, meat, equipment for the catering system, for edible oils, for sale through vending machines, dispensing devices for dosing, for milk coolers, for dairy equipment and processing of grain products. The basic sanitary and hygienic design requirements presented in EN1672-2 can be reduced to eleven items.
- Construction materials. Materials that come into contact with the product must have adequate strength over a wide temperature range, an acceptable service life, the ability to be painted, must be corrosion and wear-resistant, easy to wash and be suitable for processing; These requirements are usually met by stainless steels of various grades, selected on the basis of their specific properties to meet operational requirements — for example, 316 steel containing molybdenum is used when it is necessary to ensure corrosion resistance.
- Surface finish. Surfaces that come into contact with the product must be treated to such an extent that they are easy to clean. The quality of the surface deteriorates and abrades over time, so cleaning is difficult.
- Connections. One-piece joints (for example, welded) should be smooth and solid. Split connectors (for example, threaded couplings) should not have gaps and provide a smooth, solid surface on the product side. Suspended connections must be sealed with a gasket / gland, as they may allow the penetration of microorganisms.
- Fasteners. If possible, open threads, nuts, bolts, screws and rivets should be avoided in areas where the equipment comes in contact with the product (fig. 13.12); It is recommended to use other methods of fastening (Fig. 13.13), in which a washer with a rubber compressible insert is used to form a seal impermeable to microorganisms.
- Sewerage. All surfaces of piping and equipment should be self-draining, as the remaining liquid can promote the growth of microorganisms or (in the case of cleaning liquids) in contamination of the product.
- Internal corners. Inside corners should be radically processed as well as possible to facilitate cleaning / washing.
- "Dead" space. When designing equipment, it is necessary not only to ensure the absence of "dead" spaces, but also to take measures so that they do not appear during its installation.
- Bearings and shaft seals. In order to avoid possible contamination of the product with lubricants or bearing failures due to product ingress into them, bearings should, if possible, be installed outside the area of the product presence; shaft seals should be designed to be easy to clean (if they are not lubricated with the product, grease
Fig. 13.12. Examples of unhygienic fasteners. And - points of a delay of dirt, In - a joint metal-metal, With - the "dead" zones
must be food); Where the bearing is in the product location zone (for example, the shaft bearing of the agitator), it is important that there is a through groove in the sleeve opening for the passage of washing liquid from top to bottom.
Devices. Devices must be made of appropriate materials, and if they contain a transfer fluid (for example, a Bourdon tube pressure gauge), its use in contact with food should be authorized. It should be borne in mind that many devices, being structurally hygienic, are mounted in violation of sanitary and hygienic standards.
Doors, covers and panels. Doors, covers and panels should be designed to prevent the entry of dirt and / or prevent its accumulation; if necessary, they should be bevelled to the outer edge and should be easily removed for easy cleaning.
Fig. 13.13. Examples of sanitary fixture
Management tools. Controls should be designed to prevent the ingress of contaminants and to facilitate washing (fig. 13.14) - especially those that operators often touch with their hands.
The importance of designing with regard to sanitary and hygienic aspects in the production of chilled products can be demonstrated by the example of the production of sliced meat using slicers that are started by pressing a switch similar to that shown in Fig. 13.14. Production experienced problems associated with contamination of the product Listeria monocytogenes, due to which it was necessary to stop production for several days, which led to financial losses in excess of 1 million pounds sterling. The source of infection turned out to be L. monocytogenes, which found shelter in the switch box of the slicers. At the beginning of production, the slicer operator chose a piece of meat, put it in the slicer and pressed the start button to start cutting. From this point on, every time he consistently performed this procedure, L. monocytogenes was transferred from his hand to the slicer, and by the middle of the shift on the slicer there was a sufficient amount of L. monocytogenes on the product. The problem was solved by buying a few rubber caps for switches (fig. 13.14, b) costing a few pounds.
Fig. 13.14.a) typical switch with internal slots; b) easy to clean and hygienic version with a rubber cap
Installation of equipment
The ability to work well designed and manufactured equipment hygienically can be easily negated by insufficient attention to its placement and installation. In , as a result of an analysis of the availability of equipment, it is indicated that instead of individual pieces of equipment, it is better to purchase complex production lines. Recommended:
- to ensure normal access for inspection, cleaning and maintenance of equipment, as well as for cleaning / washing floors, sufficient room height is necessary;
- to provide access for inspection, cleaning and maintenance (especially if lifting is used) all parts of the equipment must be installed at a sufficient distance from walls, ceilings and adjacent equipment;
- Auxiliary equipment, control systems and communications connected to technological equipment should be located so as to provide access for maintenance and cleaning;
- the use of supporting frames, wall mounting and supports should be minimized, and to avoid the ingress of water or dirt, they should be made of pipes or box-section materials that should be embedded; channel bars or materials with an angular profile are not recommended;
- Base plates used for supporting and fixing equipment should have smooth, continuous and beveled surfaces that facilitate the flow of fluid, and be connected to the floor with a fillet; possible use of ball bearings;
- To reduce the likelihood of stress and damage to equipment, pipelines or connections, they must be supported not connected to other equipment.
As a method of preservation, the cooling technology already provides the consumer with many products, and in the future we can expect them to grow significantly in terms of both the range and the volume of production. Along with this, it is necessary to improve hygienic standards. It should be remembered that as long as all the technical aspects of the food refrigeration system were fully identified and analyzed, experience in this sector was accumulated for more than ten years, during which the refrigerated products, like any other types of canned food, improved and obtained a large commercial success.
Obviously, within the framework of the questions outlined in this chapter, there is a need for additional information about the ways in which pollutants spread in high-risk areas and for a greater understanding of the operation of various procedures that are currently being used to minimize them. All aspects of sanitary design that affect the ability of pathogenic microorganisms to survive, grow and be transported in high-risk areas should also be studied. It is equally important to carefully evaluate new or alternative methods that may be proposed. Such work will provide an opportunity to combine the application of design principles with the current level of microbiological knowledge in the field of cleaning and disinfection methods achieved in industries where the fight against microbiological and dust pollution is of fundamental importance (for example, the pharmaceutical industry and microelectronics). Further progress can ensure the application of the methods of the NLSSR and mathematical modeling based on work in the field of predictive microbiology and fundamental knowledge of microbiological strains capable of growth and survival under cooling conditions.
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