Chilled and frozen foods

The development of sound technology: standard operating procedures with sterilized products

Work surfaces for manual operations

Many of the operations used in the preparation or packing of the product are performed on tables or other flat surfaces. It is important that these surfaces are hygienic and technically suitable (for example, cutting cannot be performed on a stainless steel surface, although from a hygienic point of view it is beautiful and easy to keep clean). For cutting, you can use the surface of nylon, polypropylene or Teflon (Teflon). Countertops must allow for efficient performance of most operations, simple cleaning or complete cleaning without dismantling. The integrity of the surface must be restored by machining or another process, since the cut or scratched surfaces cannot be maintained in proper sanitary and hygienic condition. To ensure protection against microorganisms, it is recommended to use polyurethane or fluoroplastic conveyor belts and impregnation of surfaces with triclosan, however, in [24] it is indicated that this is effective only as additional measures, and not as a substitute for existing sanitary and hygienic measures.

Cutting and cutting slices

Many products intended for sale chilled (for example, meat and pies) are prepared or cooked in blocks. Automatic cutting or cutting after heat treatment is one of the operations for preparing consumer packages. Chisel machines can be a powerful source of infection because they are mechanically complex: they have a large number of inaccessible and unpurified places where bacteria can be stored. These microorganisms are contained in residues that are constantly formed during cutting, and are poorly removed during washing and cleaning after completion of work, and therefore they pose a danger of microbiological contamination of the product. The effectiveness of washing and cleaning procedures is reduced if the personnel performing them tries not to wet the very sensitive parts of the machines (electronic regulators, motors and sensors) that can fail when water gets into them (especially when using high-pressure cleaning). A necessary element in the design of such machines with regard to sanitary requirements is the provision of good access for washing / cleaning and control, as well as good water tightness.

Understanding the ways of repeated microbiological contamination of the product gives an analysis of the passage of the product and its residues through the machine during its operation, by which the sources and risks of reinfection can be identified. Upon completion of work and equipment cleaning, it should be re-checked to find areas where the product remained, that is, to identify areas that are difficult to clean, after which it is necessary to specifically develop, implement and monitor effective cleaning programs for such areas.

The problems of controlling the sanitary-hygienic condition of such equipment are similar to the much more widespread problems of reinfection of the product with technological equipment. Chunk and other molding machines for working with a cooked product usually work in chilled areas; this is done both to improve their technical performance and to slow down or stop the growth of microorganisms by lowering the temperature of the residues remaining in the machines. The temperature control of such machines shows the presence of multiple heat sources, which are not effectively cooled when the environment is cooled (this applies, in particular, to engines and gearboxes). In well-designed machines, this heat is removed to the machine without a significant increase in temperature, but it is also possible that there are heated areas in contact with the products or their residues, which promotes the growth of microorganisms. Often, some parts of these machines operate at temperatures far exceeding the design.

For example, when processing a material at temperatures below 4 ° C in an area whose temperature is 7-10 ° C, temperatures above 25 ° C, ideal for growing many microorganisms, can be recorded in areas of the main bearing of the cutting machine and engine of the slicer machine. During operation, such warm areas of the machines can be filled with residues of the product that linger in them, deteriorate, and then re-enter the product or on its surface. Ideally, such warm places should be eliminated while designing the equipment, but in practice, in many existing machines, such risks can only be minimized. For safe operation from the point of view of sanitary and hygienic condition, critical areas of machines should be identified, that is, warm areas in which the product remains, and then measures should be taken to properly wash and clean, cool or use other methods to minimize the growth of microorganisms and contamination of the product . In some cases, simple technical measures can improve the sanitary and hygienic characteristics of machines by reducing the amount of product retained in them and the duration of its delay.


From the moment the product has undergone a heat treatment, and before it is placed in the primary packaging and contamination is excluded, it can be moved from one production area to another many times.


In most simple technological lines, products that have been heat-treated in open vessels are placed on pallets or other containers for cooling. This container should not contaminate the product, and its shape, size and loading should ensure rapid cooling. In general, stainless steel or aluminum trays are more hygienic than plastics, which, as they wear out, become harder to clean. The thermal conductivity of plastics is also lower than the thermal conductivity of stainless steel or aluminum, and therefore metal pallets are preferable.


In most complex process lines, conveyor belts can be used to transport an unpacked product or product in an intermediate package from one operation to another. Conveyors can also be part of tunnel or spiral equipment (cooking and cooling chambers, stoves, etc.). Although different types of materials are used for conveyor belts, they can be divided into two large groups: woven (or solid) and mesh (or consisting of links). To improve hygiene, woven conveyor belts should be made of a material that does not absorb water and has a smooth surface that is easy to clean, clean and disinfect. Fabric tapes are usually used only for transportation during cooling or at ambient temperature, as they are rarely heat resistant. Continuous tapes used for heating or cooling (due to thermal conductivity) are usually made of stainless steel, which has high hygienic properties and can be heated or cooled indirectly.

Woven and other continuous ribbons can be cleaned on site with built-in nozzles (which can provide cleaning and rinsing), and can also be dried using an air scraper or vacuum system. The sanitary and hygienic problems associated with conveyors are usually caused by poor flooring or foundations, drive shafts or insufficient professional maintenance.

Conveyors with metal mesh or plastic links are used for transportation and other operations. Their main advantages are the ability to move large loads and form corners and curved sections. Metal mesh tapes are widely used in furnaces and cold stores, where hot or cold air circulation is a component of the process (for example, in spiral coolers or cooking appliances). Tapes that regularly heat or pasteurize the product do not create hygienic problems, since microorganisms in any material that lingers between the links will be destroyed by heat. When such tapes are used in coolers or for transporting unpacked products at ambient temperature, special attention should be paid to the ability of tapes to re-infect the product with microorganisms growing on the residues of the products retained on them. Purification systems must be developed that remove residues between the links (for example, by means of spray cleaning at high pressure on the lower branch of a belt conveyor). After cleaning, the tape must be disinfected or subjected to cooling to prevent the growth of microorganisms during the process. In any form of tape, it is more difficult to achieve hygiene of its work, if current maintenance is performed incorrectly or if during use the tape is damaged or wears. Special tapes are often used in product feeding, packaging and sorting systems. In such equipment, improper installation of the conveyor or its use with fragile products increases the amount of waste that arises to such an extent that even a properly designed and operated cleaning system will not maintain the conveyor in proper sanitary and hygienic condition. In order to minimize the generation of waste and, as a result, possible problems with the sanitary-hygienic state, the design of transportation systems should take into account such product characteristics as its stickiness, hardness and ability to form crumbs.

Dosing and Pumping

Most chilled products are sold in packages with a given weight, often with a constant ratio of individual ingredients (for example, meat and side dishes). If the ingredients are liquid or include small particles suspended in the liquid (about the size of 5 mm), they can be dosed using filling heads or pumping systems. When using such equipment for dispensing disinfected materials in order to ensure product safety and a specified shelf life, it requires the absence of bacteria in it, as well as the design and operation of sanitary and hygienic requirements.

Dosing and filling systems can operate at low (below 8-10 ° С), medium (20-45 ° С) or high (above 60 ° С) temperatures. The most dangerous operations are those performed at average temperatures that promote the growth of microorganisms. causing food poisoning, and if the manufacturer of products is not completely confident in the sanitary-hygienic condition of his equipment and is not ready for frequent interruptions for washing and disinfection, such temperatures should not be used. If hot filling is used, for safety it is necessary to maintain the minimum temperatures of the filling head and the remaining product. Often, in order to take into account cooling during dosing and especially during interruptions in the technological process, when the product flow stops, the ingredients' temperatures are set significantly higher than the maximum growth temperature of foodborne pathogenic microorganisms (around 55-65 ° С). If the product enters the filling heads through pipelines, it is necessary to exclude an unacceptable temperature drop at the walls of pipelines or during breaks and stops (at which the temperature is in the range that promotes the growth of microorganisms). For this, a recirculation loop can be used, in which the product returns to a heated tank or vessel. Such metering equipment is often washed using non-disinfecting washing systems, and therefore it is necessary that the pumps, valves and connections are suitable for such washing as well as for performing their main function.

weight control

When using pasteurization systems in packaging, the main role in obtaining packages with the same thermal characteristics and free space above the product in packaging is played by a reliable supply of constant quantity of the product by the dosing systems. Therefore, dosing accuracy must be carefully controlled.

Packaging Primary packaging

Chilled products are mainly sold in packaged form, the most important packaging functions being to prevent contamination and preserve the product. Packaging materials can be chosen with regard to various technical characteristics (for example, processability and heat resistance), but from a microbiological point of view, their most important properties are the ability to prevent the penetration of bacteria, mechanical strength and gas impermeability. The latter property is especially important if the packaging is a component of the product conservation system (for example, when packaging with an adjustable gaseous medium that inhibits the deterioration of the product, or when vacuum packaging). Thus, in ensuring the safety of a product, packaging equipment can perform an important function, and should be able to stably form durable, gas-tight and microorganism-impermeable (sealed) packages.

Packaging with controlled atmosphere

For many products intended for refrigerated storage, the regulation of the composition of the gas surrounding the product is a component of the preservation system. Removing oxygen from the space above the product when vacuum-packed or replacing oxygen in the process of packing with carbon dioxide, nitrogen, or a mixture of these gases gives a significant increase in shelf-life at refrigerated temperatures (for example, in the case of chilled meat). The key operating parameters for this type of packaging are the efficiency of purging and replacing oxygen with a gas mixture, regulating the level of vacuum and the frequency of producing leaky packages. It is recommended to use the [4] color indicators to indicate unsealed packages.

There are many reasons for the appearance of unsealed packages with the product - their shelf life is less and the risk of contamination is greater. Along with such reasons as the wrong choice of packaging film or equipment malfunction (for example, incorrect setting of the temperature of the sealing head, its pressure, positioning or exposure time), the main cause of rejects during packaging is contamination of the place where the pack is sealed with the product during filling. If the product or product residues remain in the sealing place, the plastic layers of the cover and the base cannot be welded together with a sealing head. Some sealing heads are specially profiled to remove contamination from the sealing location. Given the variety of combinations of profile sealing heads and filling packaging products, this can not serve as an effective solution to the problem, because the product still remains in the place of sealing, preventing the formation of a continuous seam or causing the occurrence of transverse gaps in it. Sealing problems often occur when using flat or non-profiled sealing heads, since they keep material under them when sealing. Complicated fillers are fat, water (turning into steam when heated), and fiber.

When vacuuming the packaging, a breach of sealing will be noticeable, since the packaging will not be gas tight; This can be seen or felt shortly after production. If the packaging has free space above the product, the defective packaging will be soft when compressed. If packages with the wrong amount of space above the product or with a weakened seam are processed in equipment such as autoclaves or ovens that create a pressure differential between the package and the environment, a break or weakening of the package may occur.

Other packaging

Products with a short shelf life may be an exception to the general rule of preference for packaging that is impermeable to microorganisms. Some of these products are sold in packages in which a corrugated layer (for example, aluminum) is formed between the lid and the main container. In packages of this type there is a risk of contamination of the product if the latter is not packed externally in a sealed bag. The function of such packaging trays is the formation of containers for cooking in a microwave oven or heating at home.

In addition, it is important that packaging films and pallets that come into direct contact with food should not be chemically or microbiologically contaminated. Wrapping the primary packaging, packaging that comes into contact with the product, as well as working with them in the warehouse and in the production areas should be organized to minimize the chance of contamination of the product. Therefore, the treatment, disinfection or wrapping operations used in production must fully take into account the purpose of the product and the risks that must be eliminated.

Secondary packaging

After placing the product in the primary packaging, it is fully protected from re-contamination (with hermetic packaging) or protected quite well (wrapped in a film or a bag with a corrugated seam). Primary packages sometimes have an additional secondary package, which can perform a purely decorative function, but in some cases also serves to protect the package from damage or impact when moving the product or transporting it. In the latter case, control of the characteristics of the secondary packaging should be part of the production quality assurance system.

When refrigerated products are stored or transported in boxes or tightly packed on pallets, the ability to change their temperature is limited, as the ratio of surface area to volume makes it difficult for rapid temperature changes, and the rate of heat penetration through the product and packaging is low. Therefore, it is necessary that the product in the primary packaging before the secondary packaging and stacking on pallets (pallets) has a predetermined temperature.

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