7 PREREQUISITES TO HACCP (Hans Henrik Huss/John Ryder)

Hygiene standards and procedures usually described as Good Hygienic Practices (GHP) or Good Manufacturing Practices (GMP), have been in place for many years and constituted an essential tool in traditional food control. These concepts are still essential in a modern food control system by providing the basic environmental and operating conditions for production of safe food and thus being a requisite or foundation for HACCP in an overall food safety management programme (Figure 7.1). What is new is the concept of formalising the prerequisite programme alongside HACCP and the legal requirement in some countries (USA) of documented monitoring of certain sanitation areas.

Figure 7.1 Food Safety and quality, an integrated approach (from Jouve, 1998).

In the Code of Federal Regulation (FDA, 2001) it is outlined what is covered by current GMP regulations. These include basically all procedures and practices necessary to produce safe foods.

There is no clear definition of the term Good Hygienic Practices (GHP). However, "food hygiene" has been defined by Codex (CAC, 2001) as "all conditions and measures necessary to ensure the safety and suitability of food at all stages of the food chain" and GHP can therefore be regarded as:

The terms GMP and GHP therefore basically cover the same ground and for the purpose of this book, the term GHP will mainly be used.

Various definitions of GHP or prerequisite programmes have been proposed by national and international organizations as shown:

According to the Draft Revision of the Recommended International Code of Practice for Fish and Fishery Products (CAC, 2000), the following aspects should be included in the prerequisite programme:

• requirements for fishing vessels - design and construction
• requirements for processing facility - design and construction
• design and construction of equipment and utensils
• hygiene control programme
• personal hygiene and health
• traceability and recall procedures

• training.

An example of the common prerequisite programme is given in an appendix to the publication by NACMCF (1998). Additional to the points listed by Codex it includes: Supplier control, specifications for all ingredients, chemical control and conditions for receiving, storage and shipping of raw materials and products. In the present publication some of these additional points, i.e. supplier control and specifications of ingredients, will be included in the HACCP plan and not in the prerequisite programme.

According to the US-FDA's seafood HACCP regulation (FDA, 1995), processors are required to have key sanitary conditions written into Sanitation Standard Operating Procedures (SSOPs). As outlined, SSOP are equivalent to GHP.

They are also required to monitor these conditions and practices, correct unsanitary conditions and practices in a timely manner and maintain sanitation control records. Thus the sanitation control procedures are an integrated part of the seafood HACCP regulations, but not of the HACCP-programme. The SSOP should address at least the following conditions and practices:

• safety of water and ice
• condition and cleanliness of food contact surfaces
• prevention of cross contamination from unsanitary objects to food
• maintenance of facilities for personal hygiene
• protection of food and food contact surfaces from adulteration
• proper labelling, storage and use of toxic compounds
• control of employee health conditions

• exclusion of pests.

The written SSOP plan should explain the sanitation concerns, controls, in-plant procedures and monitoring requirements. This will demonstrate commitment to buyers and inspectors and also ensure that everyone from management to production workers understands the basics of sanitation.

In the European Union (EU, the prerequisite requirements are included in both 'horizontal' legislation such as the Hygiene Directive (EC, 1993) and 'vertical' or commodity-specific legislation such as the Directive specifying the requirement for fish processing (EC, 1991).

Many activities can be considered part of a prerequisite programme depending on the product and the actual processing conditions. For this reason, it is unlikely that two processing facilities have identical prerequisite programmes.

Although definitions of prerequisites and/or SSOPs refer mostly to operational conditions, there are also basic requirements to the processing plant and the processing environment. Thus the SSOPs are specifying the quality of the water, maintenance of hygiene facilities etc., but it is equally important that the plant has access to enough water and hygiene facilities (quantitative aspects). Below is a list of key points and activities that need to be addressed in any prerequisite programme:

The Processing Plant:

• conditions of premises

• facilities:

  water, ice, steam (quantitative conditions)
  water treatment system (chlorination plant, waste water treatment)
  sanitary facilities and installations

• equipment: boxes, containers, and machinery.

Operational conditions and procedures (GHP):

• safety of water and ice (qualitative conditions)
• cleanliness of food contact surfaces
• prevention of cross contamination from insanitary objects to food
• maintenance of facilities for personal hygiene
• protection of food from adulterants
• safe storage and use of toxic compounds
• control of employee health conditions
• pest control
• waste management
• transportation
• traceability and recall procedure

• training.

A proper and well designed prerequisite programme allows the HACCP team to focus and concentrate on the hazards directly applicable to the product and the processing procedures without undue considerations and repetition of protection from hazards from the surrounding environment. It is important to point out that the prerequisite programme certainly relates to safety and therefore is an essential part of the total quality assurance programme. Thus part of the prerequisite programme (e.g. sanitation controls) must lend itself to all aspects of a Critical Control Point (CCP) such as establishing critical limits, monitoring, corrective actions, record keeping and verification procedures. However, occasional deviation from a prerequisite programme requirement would not by itself be expected to create a food safety hazard of concern. Therefore deviations from compliance in a prerequisite programme usually do not result in reaction against the product. This is in contrast to a CCP, where any deviation from the established critical limits always leads to reaction against the product.

The prerequisite programme is a good starting point for companies who have a long way to go to implement a HACCP system. Practical experience has shown that if the general issues related to the prerequisite programme are dealt with first, the HACCP study will be much more straightforward and the resulting HACCP plan easier to manage. All issues related to GMP, hygiene and the environment will be dealt with in the prerequisite programme and only truly 'critical' control points, essential to safety of the product will be included in the HACCP plan.

7.1 The processing plant

7.1.1 Plant location, physical environment and infrastructure

Early considerations in building a new plant are the identification of a suitable location. A number of factors should be considered such as physical and geographical factors and infrastructure available.

Some of the physical needs for a plant location is a plot of adequate size (for present needs and future developments), with easy access by road, rail or water. An adequate supply of potable water and energy must be available throughout the year at a reasonable cost. Special considerations must be given to waste disposal. The plant should have proper sanitary sewers. Seafood processing plants usually contain significant amounts of organic matter which must be removed before waste water is discharged into rivers or the sea. Also solid waste handling needs careful planning, and suitable space - away from the plant - must be allocated or be available.

Assessment of pollution risk from adjacent areas must also be considered. Contaminants such as smoke, dust, ash, foul odours (e.g. neighbouring fish meal plant using poor raw material) are obvious, but even bacteria may have to be considered as airborne contaminants (e.g. proximity of a poultry rearing plant upwind may be a source of Salmonella spp).

The immediate physical surroundings of a seafood factory should be landscaped and present attractive appearance to the visitor (or potential buyer of products). However, this should be done in a way that rodents and birds are not attracted. Shrubbery should be at least 10 m away from buildings and a grass free strip covered with a layer of gravel or concrete should follow the outer wall of buildings. This allows for thorough inspection of walls and control of rodents. Ground immediately in front of doors and entrances should be paved to minimize dust. All areas around the plant and facilities should be well drained to prevent any standing water, where flies and microorganisms could breed and develop.

7.1.2 Buildings, construction and layout

A food processing plant shall provide (quoted from Troller, 1993):

• adequate space for equipment, installations and storage of materials
• separation of operations to avoid cross contamination
• adequate lightning and ventilation

• protection against pests.

External walls, roofs, doors and windows should be water-, insect- and rodent-proof. Internal walls, on the other hand, should be smooth, flat, resistant to wear and corrosion, impervious, easily cleanable and white or light coloured. Also the floors should ideally be impervious to spillage of product, water and disinfectants, durable to impact, resistant to disinfectants and chemicals used, slip resistant, non-toxic, non-tainting and of good appearance and easy repairable. Floors should be provided with a slope to drains to prevent formation of puddles. All openings (doors, windows, skylights, ventilators) must be adequately screened or otherwise constructed and fitted so as to prevent the entrance of any pests (flies or rodents).

Lighting should be adequate to carry out plant operations and protected so that broken glass will not be a potential hazard.

Proper ventilation is basic to good food plant sanitation. This will control condensation and help to eliminate any mould growth. Intake air should be filtered and positive air pressure maintained in the finished product area. The technical requirements, choice of materials, costs, etc. to obtain these goals may be found in a number of publications such as Shapton and Shapton (1991), Imholte (1984), Troller (1993).

The general layout and arrangement of rooms within a processing establishment is important in order to minimise the risk of contamination of the final product. A large number of bacteria (pathogens and spoilage bacteria) enter with the raw material. To avoid cross contamination it is therefore essential that raw material is received in a separate area and stored in a separate chill room. From here the sequence of processing operations should be as direct as possible - and a "straight line" process flow is regarded as most efficient (Hayes, 1992). This layout minimises the risk of recontamination of a semi-processed product.

Clear physical (e.g. a wall) segregation between "clean" and "unclean" areas is of prime importance. "Unclean" areas are those where raw material is handled and often a cleaning operation (wash) or for example a heat treatment (cooking of shrimp) is marking the point, where the process flow goes from "unclean" to "clean" areas. Thus a "clean" area is defined:

i.e. there is no subsequent processing step that will reduce or destroy contaminating microbes.

Also cooled rooms must be separated from hot rooms where cooking, smoking, retorting etc. are taking place. Dry rooms must be separated from wet rooms and separate rooms must be provided for waste material, chemicals (cleaning and disinfection compounds, insecticides, all toxic materials), packaging materials and wood (for smoking).

The separation between the clean and unclean areas must be complete. There should be no human traffic between these areas, and equipment and utensils used in the unclean areas should never be used in the clean area. This means that there should also be separate wash and hygiene facilities for equipment and personnel in these areas. For easy identification the personnel should wear different coloured protective clothing for different operations (e.g. white in the clean and blue in the unclean).

Equally important in layout and design of food factories is to ensure that there are no interruptions and no "dead ends" in the product flow, where semiprocessed material can accumulate and remain for a long time at ambient temperature. Time/temperature conditions for products during processing are extremely important critical control points (CCPs) in order to prevent bacterial growth. This means that a steady and uninterrupted flow of all products is necessary in order to have full control of this critical factor. If any delays in product flow are necessary, the products should be kept chilled.

In addition, to facilitate product flow the factory layout and practices should ensure that:

• all functions should proceed with no criss-crossing and backtracking

• visitors should move from clean to unclean areas

• ingredients should move from "dirty" to "clean" areas as they become incorporated into food products

• conditioned (e.g. chilled) air and drainage should flow from "clean" to "dirty" areas

• the flow of discarded outer packing material should not cross the flow of products

• there is sufficient space for plant operations including processing, cleaning and maintenance. Space is also required for movement of materials and pedestrians

• operations are separated as necessary. There are clear advantages in minimizing the number of interior walls since this simplifies the movement of materials and employees, makes supervision easier, and reduces the area of wall that needs cleaning and maintenance (the list is partly after Shapton and Shapton, 1991).

Some of the principal requirements to an ideal establishment are outlined in Figure 7.3.

7.1.3 Facilities

Essential facilities in a seafood processing plant are:

• adequate supply of energy

• adequate supply of potable cold water. Hot water and steam must be available for cleaning and sanitation when necessary

• a suitable water treatment system where appropriate (chlorination plant, waste water treatment)

• adequate facilities for washing and disinfecting equipment

• adequate staff amenities (washing facilities, toilets, staff rooms).

Necessary hand-washing facilities must be located at the entrance to the processing areas and in all processing areas where GHP require employees to wash and disinfect their hands. They must be equipped with hand-cleaning and effective disinfection preparations and single use towels or other suitable hand-drying devices. Adequate and readily accessible toilet facilities must be available, properly located (no direct access to processing areas) and maintained in a hygienic condition and good repair.

Figure 7.3. Example of a simplified factory layout (drawing by V. Popescu).

7.1.4 Utensils and equipment

A great variety of utensils and equipment is used in the fish industry. There is an abundance of advice and regulations available concerning the requirements for equipment. All of them agree that the food equipment should be non-contaminating and easy to clean. In particular, all food contact surfaces (utensils, knives, tables, cutting boards, boxes and containers, conveyer belts, gloves, aprons etc.) must be designed and of such material as to be easily cleanable. Such surfaces shall be constructed of non-toxic, non-absorbent material that is resistant to the environment, the food, cleaning and disinfecting agents. Food contact materials that should be avoided are: wood, ferrous metals, brass and galvanised metals. However, the degree of stringency in hygienic requirements must be related to the product being processed. Raw fish, for example, do not require the same standard of hygiene as cooked and peeled shrimp. Criteria for hygienic design are particularly important for equipment used in the later stages of processing and particularly after a bacteria-eliminating processing step. There are seven basic principles for hygienic design agreed upon by a working party appointed by the Food Manufacturers Federation (FMF) and Food Machinery Association FMA (FMF/FMA, 1967) as quoted by Hayes (1992):

• All surfaces in contact with food must be inert to the food under the conditions of use and must not migrate to or be absorbed by the food

• all surfaces in contact with food must be smooth and non-porous so that tiny particles of food, bacteria, or insect eggs are not caught in microscopic surface crevices and become difficult to dislodge thus becoming a potential source of contamination

• all surfaces in contact with the food must be visible for inspection or the equipment must be readily disassembled for inspection, or it must be demonstrated that routine cleaning procedures eliminate possibility of contamination from bacteria or insects

• all surfaces in contact with food must be readily accessible for manual cleaning, or if not readily accessible, then readily disassembled for manual cleaning, or if clean-in-place techniques are used, it must be demonstrated that the results achieved without disassembly are the equivalent of those obtained with disassembly and manual cleaning

• all interior surfaces in contact with food must be so arranged that the equipment is self emptying or self draining

• equipment must be so designed as to protect the contents from external contamination

• the exterior or non-product contact surfaces should be arranged to prevent harbouring of soils, bacteria or pests in and on the equipment itself as well as in its contact with other equipment, floors, walls or hanging supports.

In the design and construction of equipment it is important to avoid dead areas where food can be trapped and bacterial growth takes place. Also dead ends (e.g. thermometer pockets, unused pipe work, T-pieces) must be avoided, and any piece of equipment must be designed so that the product flow is always following the "first in first out" principle

Cleanability of equipment involves a number of factors such as construction materials, accessibility and design. The most common design faults which cause poor cleanability are (Shapton and Shapton, 1991):

• poor accessibility - equipment should be sited at least 1 m from a wall, ceiling or the nearest equipment

• inadequately rounded corners - minimum radius should be 1 cm, but 2 cm is regarded as optimum by the American 3-A Sanitary Standards Committee (Hayes, 1992)

• sharp angles

• dead ends - including poorly designed seals.

One general problem of food processing involves the extremes of temperature, abundant use of water, development of condensations and contamination of food from overhead pipes and surfaces. Equipment design must consider this and include proper protection.

Equipment design is one of the major problems in modern food hygiene. A great number of new machines and equipment are designed and constructed without proper attention to the fact that these tools have to be cleaned and sanitised. The EC (1992) addresses machinery safety and hygiene regulations. Some of the highlights are:

• machinery containing materials intended to come in contact with food must be designed and constructed so that these materials can be cleaned before each use

• all surfaces and their joinings must be smooth, with no ridges or crevices that could harbour organic materials

• assemblies must be designed to minimise projections, edges and recesses. They should be constructed by welding or continuous bonding, with screws, screwheads and rivets used only where technically unavoidable

• contact surfaces must be readily cleaned and disinfected, and built with easily dismantled parts. Inside surfaces must be curved in a way to allow thorough cleaning

• liquid derived from foods, as well as cleaning, disinfecting and rinsing fluids should be readily discharged from machinery

• machinery must be designed and constructed to prevent liquids or living creatures - primarily insects - from entering and accumulating in areas that cannot be cleaned

• machinery must be designed and constructed so that ancillary substances, such as lubricants, do not come in contact with food.

The directive also sets out a certification system where machinery is checked for compliance and tagged with an EC mark if found to be satisfactory. Certification is not retrospective and manufacturers have two years to bring new machinery into compliance.

Apart from literature already cited, additional useful material and information on hygienic design are found in Milledge (1981) and Gould (1994).

A great variability exists in the size, of and extent of handling in, fish processing establishments. Accordingly, the hygienic requirements in, and the design of, fish handling areas may vary considerably. Quite obviously the requirements that a small establishment which is only repacking fish in ice and catering for a local market, must meet are different from the hygienic requirements of a large establishment that is processing a variety of sophisticated products including heat treated and composite products and exporting to countries all over the world. Also the requirements commonly listed in legislation and codes of practice are not equally important. The more important factors include: facilities for water supply, waste disposal and cooling and cold storage facilities and -capacity. Of less importance are buildings, ventilation, factory location, clothes changing facilities, lightning and roadways (ICMSF, 1988).

The forms shown in Appendix 1 have been utilized in assessing fish factories using the HACCP principles. Only the most important factors are evaluated and given a rating from A to C, where A and B are expressions of degrees of excellence and niceties, while a rating of C is given to a condition which is unacceptable and needs immediate correction before further operations can take place. Thus it is an attempt to "distinguish between the nice and the necessary" which is the same approach as applied in the HACCP principles.

7.2 Operational conditions including GHP

A range of operational conditions must be in place prior to the implementation of HACCP in order to control the risks or safety concerns related to the environment and the personnel. The existence and the performance of such a programme must be well documented with written procedures, assigned responsibilities, measurable acceptance criteria, defined record keeping activities and procedures to be followed when acceptance criteria are not met. A written standard format as shown below using 5 of the 7 HACCP principles is useful as a guideline or checklist and to ensure that all essential points have been considered.

Figure 7.4 Standard format in assessing the prerequisite programme.

7.2.1 Safety of water and ice

Criteria for potable water

Water is used in food processing both as an ingredient and for cleaning and sanitation. Thus the quality of the water is of great importance. WHO (1993) and EC (1998) have published extensive guidelines on drinking water quality where standards for more than 60 parameters have been elaborated. The microbiological criteria suggested are shown in Tables 7.1 and 7.2.

Very often water needs to go through some form of treatment and disinfection before being suitable for use in food processing.

Water treatment

Water treatments vary from region to region depending on the water sources available. While groundwater from sedimentary aquifers has undergone extensive filtration the water from hard rock aquifers or surface water sources should be filtered as part of the water treatment in order to decrease the content of particulates, microorganisms, organic and inorganic matter.

Table 7.1 Bacteriological quality of drinking water (WHO, 1996)¹.

1. Immediate investigative action must be taken if either E. coli or total coliform bacteria are detected. The minimum action in the case of total coliform bacteria is repeat sampling; if these bacteria are detected in the repeat sample, the cause must be determined by immediate further investigation.

2. Although E. coli is the more precise indicator of faecal pollution, the count of thermotolerant coliform bacteria is an acceptable alternative. If necessary, proper confirmatory tests must be carried out. Total coliform bacteria are not acceptable indicators of the sanitary quality of rural water supplies, particularly in tropical areas where many bacteria of no sanitary significance occur in almost all untreated supplies.

3. It is recognized that, in the great majority of rural water supplies in developing countries, faecal contamination is widespread. Under these conditions, the national surveillance agency should set medium-term targets for the progressive improvement of water supplies, as recommended in Volume 3 of Guidelines for drinking-water quality.

Table 7.2 Microbiological criteria for drinking water (EC, 1998).

1. Former directive 80/778/EC (EC 1980) used 100 cfu/ml as guidelines.

Parasites are removed to a large extent by filtration. The levels of bacteria and virus also decrease markedly and the removal mechanisms are both filtration and adsorption. The cation concentration influences adsorption, i.e. increasing concentrations give rise to increased adsorption. Ca²⁺ and Mg²⁺ seem to be especially efficient. These small cations will decrease the repulsive forces between the soil particles and the microorganisms. Iron oxides also have a high affinity for viruses as well as bacteria. Ferric hydroxide impregnated lignite has even been suggested as a local filtration/adsorption media (Prasad and Chaudhuri, 1989).

The disinfection efficiency is greatly affected by

• type of disinfectant,
• type and state of microorganism,
• water quality parameters such as turbidity (or suspended solids),
• organic matter,
• some inorganic compounds,
• pH

• temperature.

The "hardness" of the water may indirectly influence disinfection since deposits may harbour microorganisms and protect them from cleaning agents and disinfectants.

By far the most widespread disinfectant is chlorine but also chloramines, chlorine dioxide, ozone and UV are being used in some instances. Chlorine is cheap and available in most places and monitoring the free residual levels is simple. For disinfection WHO (1996) is recommending 5 mg chlorine/litre and for effective disinfection there should be a residual concentration of free chlorine of ³0.5 mg/l after at least 30 minutes contact time at pH <8.0. For disinfection of clean equipment up to 200 mg/l is used. To avoid corrosion a lower concentration of 50-100 mg/l and longer contact times (10-20 minutes) are often used. Current guidelines are shown in Table 7.3.

Table 7.3 Concentrations of chlorine used in fish processing.

Chloramines are more stable but less microbiocidal and much less efficient in killing parasites and virus than chlorine. Chlorine dioxide is, if anything, more microbiocidal than chlorine, especially at high pH, but there is concern with regards to the by-products. In the case of ozone and UV there is no residual matter to monitor. Ozone seems to be very efficient in killing protozoa. The efficiency of UV disinfection decreases markedly if there is any turbidity or dispersed organic matter and problems are often encountered due to a lack of lamp maintenance. The resistance of the various microbiological organisms varies a lot. In the case of most disinfectants the order of sensitivity in decreasing order is:

vegetative bacteria > viruses > bacterial spores, acid-fast bacteria and protozoan cysts.

The sensitivity varies within groups and even within species. Indicator bacteria are unfortunately among the more sensitive microorganisms and the presence of, for example, faecal coliforms in treated, disinfected water is therefore a very clear indication that the water contains potentially pathogenic microorganisms while the absence of such indicator bacteria does not guarantee pathogen-free water.

Bacteria from nutrient-poor media as well as otherwise stressed bacteria may also exhibit greatly increased resistance. Some of the effects mentioned on the efficiency of free chlorine are illustrated in Table 7.4.

Table 7.4 Inactivation of microorganisms by free chlorine.

1. C·t product of disinfectant concentration (C) in mg/l and contact time (t) in minutes for 99% inactivation (modified after Sobsey (1989))

2. BDF = buffered demand free

3. ND = no data

4. CDF = chlorine demand free

5. GAC = granular activated carbon

If microbes are associated with granular material or other surfaces the effect of a disinfectant such as chlorine decreases drastically. Attachment of Klebsiella pneumonia to glass surfaces may, for example, increase the resistance to free chlorine by 150-fold (Sobsey, 1989).

Organic matter may react and "consume" disinfectants such as chlorine and ozone and the presence will also interfere with UV light. The chloramines are less susceptible to organic matter.

pH is important in disinfection with chlorine and chlorine dioxide. There is greater inactivation of microorganisms at low pH in the case of chlorine and greater inactivation at high pH in the case of chlorine dioxide (Sobsey, 1989). In general, higher temperatures result in increased inactivation rates.

Use of non-potable water

The use of non-potable water may be necessary for water conservation purposes or desirable because of cost. Non-potable water may, for example, be surface water, sea water or chlorinated water from can cooling. Relatively clean water such as chlorinated water from can cooling operations may be used for washing cans after closing and before heat treatment, for transporting raw materials before processing (after the water has cooled off), for initial washing of boxes, for cooling of compressors, for use in fire protection lines in non-food areas and for fluming of waste material.

If potable water is used to supplement a non-potable supply the potable source must be protected against valve leakage, or back-pressure, for example, by adequate air-gaps. Back-flow, due to sudden pressure differentials or blockage of pipes, has unfortunately occurred in many systems.

Potentially contaminated water such as coastal water or surface water, should not be used at the production premises but may, if aesthetically acceptable, be used for removing waste material in places where no contact to food is possible.

Monitoring water quality

The responsible person should have continuously updated reference drawings of the pipe system and the authority to remove dead-ends. Especially in cases where a plant has undergone many changes, the piperuns, may become more and more complicated over the years. The person should also be in contact with the local waterworks and the authorities in order to be informed of special events (repairs, pollution accidents or other changes).

Water may be contaminated due to bad location of source (close to septic tanks, agriculture drainage systems), cracked or improperly sealed off piping systems or even floods and heavy rains. In the plant, contamination of the water may be due to cross-connections or backflow (back pressure or back siphonage). Where necessary, backflow should be controlled by air-gaps, vacuum breakers or check valves.

A quality monitoring scheme could consist of a plan of all the sampling points and a checklist describing what to examine and why, the frequency, who takes the sample, who does the analysis, what is the limit (value, tolerance) and what to do in case of deviation (Poretti 1990). If the water is obviously polluted there is of course no reason to wait for analytical results. The sampling frequency and the range of parameters will vary with the circumstances and a special monitoring program may be needed after repairs, or when using new water supplies, for example. A minimum monitoring program for water quality could be:

• measurement of free chlorine daily

• measurement of total viable count and coliforms on a weekly basis.

The technical procedures describing the analyses for the common indicator organisms are given in standard textbooks. The EC Directive (EC, 1998) specifies some methods and equipment to be used. The values used by the company should refer to the specific method employed and the recommendations should include how to sample (tap flow, volume, sampling vessel, labelling, etc.) and how to handle and examine the sample. Even though the commonly used methods for detecting, for example, faecal coliforms are standard analyses, faulty handling of the samples often occurs. Samples should be processed within 24 hours or less, be kept cool but not frozen (preferably below 5°C), and be kept in the dark. The impact of sunlight can be very dramatic, causing false negative results (Knøchel, 1990).

If chlorination is used for disinfection monitoring of the free chlorine level is the simplest way of checking the water treatment and should be performed most often (e.g. on a daily basis). Simple laboratory methods and commercial dip-sticks are now available for on-the-spot measurements (e.g. Merchoquant Chlor 100 from Merck). The microbiological indicator parameters may be checked less frequently. If disinfection systems that leave no residuals are being used, then checking of equipment should be done regularly. The performance of the systems may be monitored at weekly intervals using indicator bacteria measurements. Above is a model of a control programme for this particular requirement.

7.2.2 Cleanliness of food contact surfaces

All food contact surfaces should be adequately and routinely cleaned and disinfected. Cleaning and disinfection belong to the most important operations in today's food industries. In the US, the term sanitation is sometimes used to describe the disinfection process. In some cases, sanitation may refer to the whole cleaning and disinfection process.

The cleaning and disinfection process can be divided into clearly distinct operations. However, these are linked firmly together in that the final result will not be acceptable unless all processes are carried out correctly.

The various steps included in a complete cycle are outlined below.

• remove food products, clear the area of bins, containers, etc.

• dismantle equipment to expose surfaces to be cleaned

• remove small equipment, parts and fittings to be cleaned into a specified area. Cover sensitive installations to protect them against water etc.

• clear the area, machines and equipment of food residues by flushing with water (cold or hot) and by using brushes, brooms, etc.

• apply the cleaning agent and use mechanical energy (e.g. pressure or brushes) as required

• rinse thoroughly with water to completely remove the cleaning agent after the appropriate contact time (residues may completely inhibit the effect of disinfection)

• control of cleaning

• disinfect with chemical disinfectants or heat

• rinse the disinfection chemicals off with water after the appropriate contact time. This final rinse is not needed for some compounds e.g. H₂O₂ based formulations that decompose rapidly

• after the final rinse, reassemble equipment and allow to dry

• control of cleaning and disinfection

• in some cases it would be good practice to re-disinfect (e.g. with hot water or low levels of chlorine) just before production starts.

Cleaning

In the preparatory phase, the processing area is cleared of remaining products, spills, containers and other loose items. Machines, conveyors, etc. are dismantled so that all locations where microorganisms can accumulate become accessible for cleaning and disinfection. Electrical installations and other sensitive systems should be protected against water and the chemicals used.

Before use of the cleaning agent, a gross food debris removal procedure should be carried out by brushing, scraping or similar action. All surfaces should be further prepared for the use of cleaning agents by a pre-rinse activity, preferably with cold water so as not to coagulate the proteins. Hot water may be used to remove fat or sugars in cases where protein is not present in significant amounts.

Completion of the preparatory work should be checked and recorded, as with any other process to ensure the quality of the complete cycle of cleaning and disinfection.

Cleaning is undertaken to remove all undesirable materials (food residues, microorganisms, scales, grease, etc.) from the surfaces of the plant and the process equipment, leaving surfaces clean, as determined by sight and touch and with no residues from cleaning agents.

Microorganisms present will either be incorporated in the various materials or attached to the surfaces as biofilms. The latter will not be removed completely by cleaning, but experience has shown that a majority of the microorganisms will be removed. However, there will still be some left to be inactivated during the disinfection. Bacteria in biofilm can be up to 1,000 times more resistant to common disinfectants compared to when in the free state.

The effectiveness of a cleaning procedure in general depends upon:

• the type and amounts of debris to be removed

• the chemical and physio-chemical properties of the cleaning agent (such as acid or alkali strength, surface activity, etc.) at the concentration, temperature and exposure time used

• the mechanical energy applied e.g. turbulence of cleaning solutions in pipes, stirring effect, impact of water jet "elbow-grease", etc.

• the condition of the surface to be cleaned.

Some surfaces, e.g. corroded steel and aluminium galvanised metal can not be cleaned easily which means that disinfection also becomes very inefficient. The same applies to other surfaces, e.g. wood, rubber, etc. The preferred material is high quality stainless steel.

The types of residues to be removed in food plants, will mainly be the following:

• organic matter, such as protein, fat and carbohydrate. These are most effectively removed by strong alkaline detergents (especially caustic soda, NaOH)

• inorganic matter, such as salts of calcium and other metals. In beer stone, milk stone, etc. salts are encrusted with protein residues. These are most effectively removed by an acid cleaning agent

• biofilms, formed by bacteria, moulds, yeast and algae can be removed by cleaning agents that are effective against organic matter.

Most cleaning agents work faster and more effectively at higher temperatures, so it can be profitable to clean at a high temperature. Cleaning is often carried out at 60-80°C in areas where it pays, energy-wise, to use such high temperatures.

Water is used as a solvent for all cleaning and sterilising agents and also for intermediate rinses and the final rinse of equipment. The chemical and microbiological quality of the water is important for the efficiency of the cleaning procedures as already described in a previous section of this Chapter. In principle, water used for cleaning must be potable.

Hard water contains a large amount of calcium and magnesium ions. When the water is heated, any calcium and magnesium salts will precipitate as insoluble salts. Also, some cleaning agents, especially alkalis, can precipitate calcium and magnesium salts.

Apart from reducing the effectiveness of detergents hard water leads to the formation of deposits or scales. Scales are not only unsightly but objectionable for several reasons:

• they harbour and protect microorganisms

• they reduce the rate of heat exchange on heat exchange surfaces. This could lead to under-processing, under-pasteurisation or under-sterilisation

• presence of scales tends to increase corrosion.

The formation of scales can be reduced by addition of chelating and sequestering agents, which bind calcium and magnesium in insoluble complexes. However, it is advisable to prevent precipitations by softening the water before it is used for cleaning. Softening can be effectively achieved by ion exchange, in which the calcium and magnesium ions are replaced by sodium ions, the salts of which are soluble. A modern, and more costly, method of softening water is by means of reverse osmosis.

To be effective, a suitable detergent or cleaning agent must be applied. The ideal detergent would be characterized by the following properties:

• it possesses sufficient chemical power to dissolve the material to be removed

• it has a surface tension low enough to penetrate into cracks and crevices; it should be able to disperse the loosened debris and hold it in suspension

• if used with hard water, it should possess water softening and calcium salt dissolving properties to prevent precipitation and build-up of scale on surfaces

• it rinses freely from the plant, leaving this clean and free from residues, which could harm the products and affect sterilisation negatively

• it does not cause corrosion or other deterioration of the plant. It is recommended always to check by consulting the supplier of machines, etc.

• it is not hazardous for the operator

• it is compatible with the cleaning procedure being used, whether manual or mechanical

• if solid, it should be easily soluble in water and its concentration easily checked

• it complies with legal requirements concerning safety and health as well as biodegradability

• it is reasonably economical to use.

A detergent with all these characteristics does not exist. So one must, for each individual cleaning operation, select a compromise by choosing a usable cleaning agent and water treatment additives so that the combined detergent has the properties that are most important for the procedure concerned.

All cleaning methods, including foams and soaks, require sufficient contact time to fully loosen and suspend soils. A moderately alkaline detergent, which is normally used in plants processing high protein foods such as fish, will typically require 10-15 minutes to fully loosen most processing soils.

Disinfection

Traditionally, the terms "disinfection" and "disinfectants" are used to describe procedures and agents used in food industries to ensure a microbiologically acceptable standard of hygiene. It is realised that the procedures and agents described will rarely introduce "sterility" i.e. total absence of viable microorganisms.

Disinfection can be effected by physical treatments such as heat, U.V. irradiation, or by means of chemical compounds.

Use of heat in the form of steam or hot water is a very safe method and a widely used method of disinfection. The most commonly used chemicals for disinfection are shown in Table 7.5.

With the use of chemical disinfectants, the death rate for microorganisms depends, among other things, upon the agent's microbiocidal properties, concentration, temperature and pH as well as the degree of contact between disinfectant and microorganisms. Good contact is obtained by stirring, turbulence, smooth surfaces and low surface tension. As with heat disinfection, different microorganisms show different resistance to chemical sterilants. Contamination by inorganic or organic matter can reduce the death rate considerably.

The desirable plant disinfectant would be characterized by the following properties:

• it has sufficient anti-microbial effect to kill the microorganisms present in the available time and should have a sufficiently low surface tension to ensure good penetration into pores and cracks

• it rinses freely from the plant, leaving this clean and free from residues which could harm the products

• it does not lead to development of resistant strains or any surviving microorganisms

• it does not cause corrosion or other deterioration of the plant. It is recommended that the suppliers of machines etc. be asked before chlorine or other aggressive disinfectant are used

• it is not hazardous to the operator

• it is compatible with the disinfection procedure being used, whether manual or mechanical

• if solid, it should be easily soluble in water

• its concentration is easily checked

• it is stable for extended storage periods

• it complies with legal requirements concerning safety and health as well as biodegradability

• it is reasonably economical in use.

It will often be necessary to combine disinfectants with additives in order to obtain the required properties. The following are among the most widely used disinfectants and shall be described briefly.

Chlorine is one of the most effective and widely used disinfectants. It is available in several forms, for instance sodium hypochlorite solutions, chloramines and other chlorine containing organic compounds. Gaseous chlorine and chlorine dioxide are also used. Chlorinated disinfectants at a concentration of 200 ppm free chlorine are very active and have a cleaning effect. The disinfectant effect is considerably decreased when organic residues are present. The compounds dissolved in water will produce hypochlorous acid, HOCl, which is the active disinfecting agent, acting by oxidation. In solution it is very unstable, particularly in acid solution where toxic chlorine gas will be liberated. Furthermore, solutions are more corrosive at low pH.

Unfortunately, the germicidal activity is considerably better in acid than in alkaline solution, thus the working pH should be chosen as a compromise between efficiency and stability. Organic chlorinated disinfectants are generally more stable but require longer contact times. When used in the proper range of values (200 ppm free chlorine), chlorinated disinfectants in solutions at ambient temperatures are non-corrosive to high quality stainless steel, but they are corrosive to other less resistant materials.

Table 7.5 Types of disinfectants (based on anon. 2000).

1. CIP = cleaning in place

Iodophors contain iodine, bound to a carrier, usually a non-ionic compound, from which the iodine is released for sterilisation. Normally the pH is brought down to 2-4 by means of phosphoric acid. Iodine has its maximum effect at this pH range.

Iodophors are active disinfectants with a broad antimicrobial spectrum like chlorine. They are inactivated by organic material. Concentrations corresponding to approximately 25 ppm free iodine will be effective.

Commercial formulations are often acidic making them able to dissolve scales. They can be corrosive depending on the formulation and they should not be used above 45°C as free iodine may be liberated. If residues of product and caustic cleaning agents are left in dead ends and similar places, this may, in combination with iodophores, cause very unpleasant "phenolic" off-flavours.

Hydrogen peroxide and peracetic acid are effective disinfectants acting by oxidation and with a broad antimicrobial spectrum. Diluted solutions may be used alone or in combination for disinfection of clean surfaces. They lose their activity more readily than other disinfectants in the presence of organic substances and they rapidly lose their activity with time. They should be used in concentration of 200-300 ppm.

Quaternary ammonium compounds are cationic surfactants. They are effective fungicides and bactericides but are often less effective against Gram negative bacteria. To avoid development of resistant strains of microorganisms, these compounds should only be used by alternating with the use of other types of disinfectants.

Due to their low surface tension, they have good penetrating properties and for the same reason, they can be difficult to rinse off. If quaternary ammonium compounds come into contact with anion-active detergents, they will precipitate and become inactivated. Mixing or successive use of these two types of chemicals must therefore be avoided. They can be used in concentrations of 200 ppm on food contact surfaces. Table 7.6 summarizes the concentrations of commonly used disinfectants.

Table 7.6 Disinfectant concentrations commonly used in food plants (anon., 2000).

1. The higher end of the listed range indicates the maximum concentration permitted without a required rinse (surfaces must drain)

2. Includes mix of oxychloro compounds

3. Monitoring of cleaning and disinfection

Effective cleaning is a prerequisite for an efficient disinfection. This indicates the importance of controlling cleaning. The most important control is sensory (visual, touch, smell) inspection to demonstrate:

• that all cleaned surfaces are visibly clean

• that all surfaces, by feeling, are free from food residues, scales and other materials and, by smelling, free from undesirable odours

Further, the concentrations and pH-values of cleaning agents, the temperatures, if hot cleaning is used, and the contact times should be monitored and registered. pH measurements, or similar testing, of rinse water may be used to ensure that the cleaning agent is removed so that it will not interfere with the disinfectant. These controls are all rapid and allow immediate decisions to be made as to whether cleaning should be repeated, partly or completely, or to proceed to the process of disinfection. All actions shall be registered as part of the Quality System. At this stage, microbiological control serves no real purpose. Firstly biofilms and surviving microorganisms are likely to be present and secondly, reliable rapid methods are not available.

Control of disinfection will be the final control of the complete cycle of cleaning and disinfection. Provided cleaning has been controlled effectively as described above, control of disinfection will be effective when the following conditions are met:

• control of time and temperature conditions for disinfection by heat
• control of active concentrations of chemical disinfectant
• control that all surfaces to be disinfected are covered by the disinfectant

• control of contact time.

The above controls should be documented and the observations reported and registered as required in standard Quality Systems.

Microbiological testing and control serve the purpose of verification. Various techniques are available, but none are ideal and they are not "real time" methods. "Real time" methods are highly desirable for control of cleaning and disinfection. Methods (bacterial counting) that require overnight incubation are too late to correct critical situations. However, if conducted at regular intervals and planned to cover all critical points, useful information from microbiological control can be accumulated with time. Various methods are used and shall be mentioned briefly.

• swab testing. This is the most usual technique and one of the better ones. By use of a sterile swab of cotton-wool, part of the disinfected surface is swabbed, and the bacteria now on the swab are transferred to a diluent for determination of colony forming units in standard agar substrates. Swabs are especially useful in places where other control methods can only be used with difficulty i.e. pockets, valves, etc.

• final rinse water. Membrane filtration of rinse water and incubation on agar substrate is a very sensitive technique for control of CIP systems as well as other cleaning and disinfection systems, where a rinse can be applied

• direct surface plates. In these methods petri dishes or contact slides with selective or general purpose agar media are applied to the surface to be examined, followed by incubation and counting of colony forming units. These techniques can only be applied to flat surfaces, which is a limiting factor

• bioluminometric assay of ATP. This is almost a "real time" method giving the answer within minutes. It is very sensitive and can be combined with swabbing for collection of microorganisms from surfaces. The method is rather non-specific, and it may not be able to distinguish between microorganisms and food residues. However, if applied under defined conditions it may prove useful and superior to the conventional methods because it provides the answer in minutes.

Regardless of the technique used, it is valuable to know from the verification analyses that the system was working when it was established. There is also a value in knowing trends as expressed in the verification results recorded. The objective of studying trends and conducting the microbiological control of cleaning and disinfection will be to take corrective action before loss of control of products or processes occur.

7.2.3 Prevention of cross-contamination

A key element in any hygiene programme is the prevention of cross-contamination, i.e. contamination of final product with any hazards originating in the raw material or the processing environment. This is of particular concern if the final product is a ready-to-eat product that is not usually cooked before being eaten. There are many possible routes of contamination of the final product as shown in Figure 7.5. It is not always possible to identify the most important routes and all of them must be included in a preventive programme.

Figure 7.5 Routes of contamination in a seafood processing plant.

The main preventive measures to avoid cross-contamination are:

• a clear and effective separation of raw material and cooked or ready-to-eat products during processing, handling and storage (see section 7.1)

• proper employee hygiene, clothing and handling practices

• restricted and controlled traffic or movement about the plant (employees, product, equipment)

• food handling and processing areas and equipment adequately cleaned and disinfected (see section 7.2.2)

• use of potable water (see section 7.2.1).

Personnel can contaminate the final product directly with pathogens from their skin or hands, digestive system or respiratory tract. They can also function as an intermediary vector carrying bacteria, virus, etc. from raw material or the environment to the product. For this reason, employee hygiene and food handling practices are very important - particularly when ready-to-eat products are handled. Below some points on personal hygiene to consider in this part of the prerequisite programme:

• clean protective clothing, footwear, hair- and beardnets, caps or other effective hair restraints must be issued by the company and should be worn in the processing area only

• nail varnish, false nails and eyelashes, watches and jewellery should not be worn in processing area

• personal items (handbags, shopping bags, etc.) must not be taken into processing area

• eating food or sweets, chewing gum, drinking beverages or using tobacco should not occur in any processing area and spitting should be forbidden

• an effective hand washing program should be implemented, including:

  • how to wash hands:

    • wet hands with warm water
    • lather and rub using warm water
    • rinse
    • dry with disposable towels or

    • disinfect by dipping in sanitizing solution (iodine or 100 ppm chlorine).

  • when to wash hands:
  • before starting work - in the mornings and after breaks
  • after visiting the toilet
  • after coughing and sneezing

  • after handling soiled equipment

7.2.4 Maintenance of facilities for personal hygiene

According to the US Federal Seafood HACCP regulations (FDA, 1995) the condition of the personal hygiene facilities should be monitored separately.

The number and location of toilets and hand-washing facilities needs consideration. An adequate number of readily accessible toilet facilities must be available and maintained in a hygienic condition and good repair. Hand-washing facilities must be strategically and conveniently located near toilets and at entrances to the processing areas. Wash basin taps must not be hand-operated.

Hand-washing facilities should be dedicated to hand-washing only and never be used for washing dishes, utensils or equipment. Similarly, hand-washing should never take place in sinks or tanks used for food preparation. Hand-washing facilities should include:

• liquid soap in a dispenser
• hot water (~40-43°C)
• disposable paper towels or air blowers (- refuse receptacles if needed)

• hand disinfection facilities (bowls for hand dip).

Typically hand disinfectants are composed of chlorine compounds (100-200 ppm chlorine) or iodine compounds (20-25 ppm iodine).

7.2.5 Protection of food from adulterants

Food, food contact surfaces and food packaging material must be protected from adulteration with filth, lubricants, fuel, pesticides, cleaning compounds, disinfection agents, condensates, floor splash and other chemical, physical and biological agents. Thus it is clear, that this part of the programme goes beyond safety aspects addressing also contamination with filth.

Processors need to be aware of all avenues that could cause the food to be adulterated. The maintenance department needs to establish a regular maintenance programme for the facility's ventilation system to avoid formation of condensation. Also floors must be maintained in good order to avoid formation of pools of water and supervisors must ensure that no floor splash occurs during processing or when food is exposed.

Only food grade lubricants should be used on all moving machinery parts that come into direct contact with food. Only approved chemicals for cleaning, disinfection, pesticides and rodenticides should be uses in the processing plant.

7.2.6 Proper labelling, safe storage and use of toxic compounds

All food processing plants use chemicals such as cleaning agents, disinfectants, rodenticides, insecticides, machine lubricants and various additives. These chemicals must always be used according to the manufacturer's instructions, have proper labelling and be stored in a safe manner that protects against contamination of food or food contact surfaces. Original containers (stock solutions) must be kept in a separate room for this purpose only. Working solutions of cleaning and/or disinfection compounds should be in the processing area only when in use - and when no food products are handled.

7.2.7 Control of employee health conditions

It is well known that poor personal hygiene has been implicated in a number of food-borne disease outbreaks. Even apparently healthy persons may carry pathogens, which can spread and contaminate food. However, persons showing symptoms such as: diarrhoea, vomiting, open skin sores, boils, fever, jaundice or discharge from ear, eye or nose, are likely to be infected with pathogens that can be transmitted to food. A food worker displaying any of these symptoms should therefore be excluded or restricted from food handling areas.

7.2.8 Pest control

This programme relates to pests such as rodents, birds and insects as well as dogs and cats. These pests can carry a variety of human disease agents, which can be introduced into the processing environment. For this reason, the presence of pests in a processing plant is unacceptable.

A pest control programme should be based on three principles:

• exclusion or preventing access
• restriction by avoiding to create an environment conducive to pests

• destruction and eradication. This part of the programme must be carried out by qualified personnel as strong poison may be handled. An outside, specialist company is often contracted to carry out this part of the programme.

7.2.9 Waste management

All offals and other waste materials must be removed from the processing area and premises on a regular basis. Separate facilities for containment of offal and waste material must be provided for this purpose only and those facilities should be properly maintained. A hygienic waste water disposal system must be in operation. Sewage disposal shall be made into an adequate sewerage system or disposed of through other adequate means.

7.2.10 Storage and transportation

The conditions for storage and transportation must be as such to minimise contamination and damage of the fish. Storage areas and vehicles used for the transportation of fish and fish products must be clean. They must provide the fish with protection against contamination from dust and exposure to higher temperatures. Where appropriate, vehicles must be fitted with refrigeration and equipment to maintain fish at 0°C (chilling) or £-18°C (freezing). Below is an example of this part in a prerequisite programme.

7.2.11 Traceability and recall procedures

A system for tracing all raw materials and finished products is a necessary component in a prerequisite programme. No process is fail-safe and traceability that includes lot identification is essential to an effective recall procedure. A crisis response plan should be in place to handle any incidents.

Appropriate records of processing, production and distribution should be kept and retained for a period that exceeds the shelf life of the product. Where there is a health hazard, products produced under similar conditions may be withdrawn. The need for public warning should be considered. Once retrieved, products must be held under supervision until the manner of product disposition e.g. rework or destruction has been determined.

7.2.12 Training

All employees should receive documented training on personal hygiene, GHP, cleaning and disinfection procedures, product handling and protection, the HACCP-system and process control. Periodic refresher training should be part of the overall training programme. Training in basic food hygiene is fundamentally important. All personnel should be aware of their roles and responsibilities in protecting fish and the fish products from contamination and deterioration.

An example of a checklist to be used in assessing the prerequisite programme is shown in Appendix 1.

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