Categories
Chilled and frozen foods

Cleaning and disinfection

CLEANING И DISINFECTION

JK. Jolla Campden and Chorleywood Food Research Association

1. INTRODUCTION

В last The chapter outlined the concept of hygiene design and hygiene practices to ensure the safety of chilled food. In this chapter, we will look at the hygiene practices associated with cleaning and disinfection.

There are four main sources of food contamination: raw materials used; surfaces of equipment, buildings and structures; people and animals; air. Control of raw materials is discussed in other chapters of this book, and raw materials are the only source of infection that does not pertain to the production environment itself. The product may be contaminated by moving on surfaces in contact with it, in contact with the product of people (operators) or animals (pests). Air can act as a source of contamination (outside air) or as a transport medium (for example, transferring contaminants from surfaces that do not come into contact with the product, to surfaces in contact with it).

Provided that the production environment and production equipment are planned and constructed in compliance with sanitary and hygiene standards, cleaning and disinfection (called sanitation) are the main ways to combat food contamination from the environment every day. When properly implemented, sanitation programs are beneficial and simple, and if implemented aggressively, they can reduce the risk of contamination of the product with microorganisms or foreign matter. Given the need to maintain high hygiene standards for the production of chilled products with a short shelf life and the requirements of customers, consumers and legislation aimed at constantly tightening hygiene standards, sanitization requires the same degree of attention as any other process for the production of safe and healthy chilled products.

In this chapter, we will consider sanitizing only hard surfaces - equipment, floors, walls, and accessories, as other surfaces (such as work clothes or leather) are discussed in the sections on personal hygiene. With this approach, surface sanitation is performed to solve the following problems:

♦     removal of microorganisms or conditions conducive to their growth, which reduces the likelihood of infection by pathogenic microorganisms and, reducing the number of microorganisms causing spoilage, can increase the shelf life of some products;

♦     removal of materials that may lead to contamination of products with impurities and create conditions for the propagation of rodent pests; due to the removal of food materials remaining on the processing line that may deteriorate and fall into subsequent batches of the product, this also improves the appearance and quality of the product;

♦     increasing the service life of equipment, preventing damage to equipment and communications, ensuring a safe and clean working environment for personnel, comfortable working conditions and an increase in its productivity;

♦     the formation of a positive image of the enterprise in the eyes of customers and the public, since the first impression of a sloppy or dirty production area, and therefore of poorly organized production, can be difficult to overcome.

2. PRINCIPLES sanitization

Sanitary and preventive measures are carried out primarily in order to most effectively remove from the surface all unwanted materials (food residues, microorganisms, impurities and detergents) to a level at which everything that remains would pose a minimal threat to the quality or safety of the product . Such undesirable material (usually called contamination) can form during normal production, spills, congestion, during line operation, during equipment maintenance, during packaging, or as a result of general pollution of the production environment with dust or dirt.Strongly. To implement the appropriate program of sanitary and preventive measures, it is necessary to determine the nature of the contaminants to be removed.

Product residues are easy to see and can be characterized by chemical composition (e.g. carbohydrate, fat, protein or starch). It is also important to know the technological parameters and environmental factors, since the same food pollution can require different cleaning methods, which mainly depend on humidity and temperature. The higher the temperature of food pollution (especially after baking) and the longer the time before the start of sanitary-hygienic processing (that is, the drier the pollution becomes), the more difficult it is to remove them.

Microorganisms can either be contained inside dirt particles, or settle on surfaces and form layers or biofilms. A number of factors are known that influence the settling of microorganisms and the formation of biofilms (colonies) - in particular, the level and type of microorganisms, the properties of the treated surface layer, the nature and roughness of the substrate, temperature, pH, time and the presence of nutrients. A number of reviews have been published on the formation of biofilms in the food industry. Typically, biofilm formation occurs only on production surfaces, and the growth of attached colonies is limited to regular cleaning and disinfection.

ПOn the results of the study of colonies in 17 different production environments, 79% of all isolates were gram-negative bacilli, 8,6% were gram-positive cocci, 6,5% were gram-positive bacilli, and 1,2% were yeast strains. The most common microorganisms were Pseudomonas species., Staphylococcus and Enterobacter. Pseudomonas aeruginosa (Pseudomonas) in the environment are psychrotrophic microorganisms that easily settle on surfaces and are common microorganisms that cause spoilage of chilled foods. Other common gram-negative microorganisms that settle on surfaces include E. coli, which are widespread in the environment. Their presence may indicate poor sanitation or contamination after it. Staphylococci are most often transferred from human skin, and therefore their presence on surfaces may be the result of transfer from the hands of operators. ПAfter study of the microflora of surfaces in the manufacture of milk, meat and confectionery products, it was concluded that the microflora is mainly determined by the working environment.

Bacteria that settle on surfaces in contact with the product can become a source of potential contamination and lead to serious hygiene problems and economic loss due to food spoilage. For example, Pseudomonas aeruginosa and many gram-negative microorganisms found on surfaces are microorganisms that cause spoilage of chilled products. The survival of microorganisms in biofilms can be a source of contamination after processing the product, which reduces the shelf life of the product. Also listeria monocytogenes were isolated from the surfaces of food processing equipment, it is usually sought in high-risk production areas using an environmental sampling plan.

In accordance with the principles of HACCP, if the food manufacturer believes that biofilms pose a threat to the safety of the product, one or another measure should be taken to combat them - in particular, the creation of such an industrial environment in which the formation of biofilms would be limited, careful implementation of programs cleaning and disinfection, monitoring and control of these programs to ensure their successful implementation, as well as checking the results using appropriate (usually microbiological) methods.

Within the framework of the program of sanitary and hygienic measures, the cleaning stage can be divided into three stages and supplemented by a fourth stage - disinfection:

♦ the washing solution moistens the contamination and the surface of the equipment, after which it penetrates the pollution;

♦     a washing solution reacts with contamination and a surface that facilitates the peptization of organic materials, dissolution of soluble organic materials and minerals, emulsification of fats, as well as dispersion and removal of solid contaminants from the surface;

♦     re-precipitation of dispersed contamination onto a cleaned surface is prevented;

♦     by moistening the remaining microorganisms with a disinfectant solution, the reaction with cell membranes and / or the penetration of a microorganism into the cell to provide a biocidal or biostatic effect is facilitated. Depending on whether the disinfectant contains a surfactant and the selected disinfection method (with or without flushing), microorganisms can be removed from the surface.

To carry out these four stages in sanitary-hygienic programs, a combination of four main factors is used, and their specific combinations for different cleaning systems vary (usually, if the use of one energy source is limited, it can be compensated by the large use of others):

♦     mechanical or kinetic energy;

♦     chemical energy;

♦     temperature or thermal energy;

♦     the time.

Mechanical or kinetic energy is used to physically remove contaminants. This includes scraping, manual brushing and automatic cleaning with a scraper or a hard brush and pressure washing (liquid cleaning). Of these four factors, the first three are considered the most efficient in transferring energy., liquid cleaning efficiency and the effect of pressure head. Mechanical methods are most effective for removing biofilms.

Chemical energy is used during purification to destroy contaminants in order to facilitate their removal and transfer into suspension. By the time this book was prepared, there were no detergents on the market that helped remove microorganisms. In chemical disinfection, chemicals react with microorganisms remaining on the surfaces after cleaning, reducing their viability. The chemical effects of cleaning and disinfection with increasing temperature increase linearly and double approximately every 10 ° C of temperature rise. For greasy and oily contaminants, temperatures above their melting points are used. Effect of washing ability on washing / cleaning and disinfection. For cleaning processes using mechanical, chemical and thermal energy, the longer the processing time, the more efficient the process. If long periods of time can be used in sanitary-hygienic programs (for example, soaking in tanks), then other energy influences can be reduced (for example, detergent concentration is reduced, lower temperature is used or mechanical cleaning by brushes is reduced).

Surface contamination is a natural process that reduces the free energy of a system. Therefore, when implementing the sanitary-hygienic program, pollution should receive additional energy to reduce surface interactions both between pollution particles and between pollution particles and equipment. The mechanics and kinetics of these interactions well understoodwhere issues beyond the scope of this chapter are raised. From a practical point of view, it is worth considering the principles that underlie the simple removal of contaminants, as they affect the management of hygiene programs.

The removal of contaminants from the surface slows down so that the logarithm of the remaining mass of contaminants per surface unit varies linearly with the cleaning time, and, therefore, the kinetics of the process corresponds to the kinetics of the first-order reaction. This approximation, however, operates in the central part of the graph, and in practice, the removal of contaminants is faster at first and slower at the end than the first-order reaction predicts. The reasons for this are unclear, but at the beginning of the process large volumes of oil that have not yet adhered to the surface are usually easily removed from it, and at the end of the cleaning process, contaminants that are in the surface irregularities or are somehow protected from the cleaning effect are more difficult to remove.

Therefore, standard cleaning operations cannot achieve 100% efficiency and contamination deposits (possibly including microorganisms) will persist during multiple contamination / cleaning cycles. As they accumulate, the cleaning efficiency will decrease, and deposits of contaminants may increase exponentially over time. The duration of such accumulation of contaminants for different technological processes will be different and can range from hours (for example, for heat exchangers) to several days or weeks. In practice, this depends on the use of periodic cleaning. Periodic cleaning is used to achieve a baseline level of accumulation of contaminants deposited on the surface, and this is achieved either by increasing the cleaning time, or by increasing the amount of energy supplied (for example, using higher temperatures, other chemicals or manual cleaning with a brush). A typical example of periodic cleaning is cleaning / washing at the end of the working week or periodic cleaning of tank bottoms.

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