360 Chilled foods In addition to process areas, provision may have to be made for a wide rar of activities including raw material storage, packaging storage, water storage wash-up facilities; plantroom; engineering workshop; cleaning stores, micro- biology, chemistry and QC laboratories, test kitchens, pilot plant; changing facilities: restrooms: canteens: medical rooms: observation areas/viewing galleries and finished goods dispatch and warehousing Other good design principles given by Shapton and Shapton(1991)are The flow of air and drainage should be away from clean areas towards The flow of discarded outer packaging materials should not cross, or run counter to, the flow of either unwrapped ingredients or finished products Detailed information on the hygienic design requirements for the construction of the external walls or envelope of the factory is not easily found. Much of the data available is understandably concerned with engineering specifications, which are not considered in this chapter. Shapton and Shapton(1991), Imholte 1984) and Timperley(1994)discuss the various methods of forming the external walls and give a large amount of advice on pest control measures, articularly for rodents. A typical example of a suitable outside wall structure shown in Figure 13.3. The diagram shows a well sealed structure that resists pest ingress and is protected from external vehicular damage. The ground floor of the factory is also at a height above the external ground level. By preventing direct access into the factory at ground floor level, the entrance of contamination(mud, soil, foreign bodies etc. ) particularly from vehicular traffic(forklift trucks, raw material delivery etc. )is restricted In addition, the above references provide considerable information on the hygienic requirements for the various openings in the envelope, particularly doors and windows. Points of particular interest are Doors should be constructed of metal, glass reinforced plastic (GRP)or plastic, self-closing, designed to withstand the intended use and misuse and be suitably protected from vehicular damage where applicable Exterior doors should not open directly into production areas and should emain closed when not in use. Plastic strip curtains may be used as inner doors If possible, factories should be designed not to have windows in food processing areas. If this is not possible, e.g. to allow visitor or management observation, windows should be glazed with either polycarbonate or and their locationg, si ister, detailing all types of glass used in the factory laminated A glass reg Metal or plastic frames with internal sills sloped(200-40.)to prevent their use as temporary storage places and with external sills sloped at 60 to prevent bird roosting, should be used Opening windows must be screened in production areas and the screens be designed to withstand misuse or attempts to remove them
In addition to process areas, provision may have to be made for a wide range of activities including raw material storage; packaging storage; water storage; wash-up facilities; plantroom; engineering workshop; cleaning stores; microbiology, chemistry and QC laboratories; test kitchens; pilot plant; changing facilities; restrooms; canteens; medical rooms; observation areas/viewing galleries and finished goods dispatch and warehousing. Other good design principles given by Shapton and Shapton (1991) are: • The flow of air and drainage should be away from ‘clean’ areas towards ‘dirty’ ones. • The flow of discarded outer packaging materials should not cross, or run counter to, the flow of either unwrapped ingredients or finished products. Detailed information on the hygienic design requirements for the construction of the external walls or envelope of the factory is not easily found. Much of the data available is understandably concerned with engineering specifications, which are not considered in this chapter. Shapton and Shapton (1991), Imholte (1984) and Timperley (1994) discuss the various methods of forming the external walls and give a large amount of advice on pest control measures, particularly for rodents. A typical example of a suitable outside wall structure is shown in Figure 13.3. The diagram shows a well sealed structure that resists pest ingress and is protected from external vehicular damage. The ground floor of the factory is also at a height above the external ground level. By preventing direct access into the factory at ground floor level, the entrance of contamination (mud, soil, foreign bodies etc.), particularly from vehicular traffic (forklift trucks, raw material delivery etc.) is restricted. In addition, the above references provide considerable information on the hygienic requirements for the various openings in the envelope, particularly doors and windows. Points of particular interest are: • Doors should be constructed of metal, glass reinforced plastic (GRP) or plastic, self-closing, designed to withstand the intended use and misuse and be suitably protected from vehicular damage where applicable. • Exterior doors should not open directly into production areas and should remain closed when not in use. Plastic strip curtains may be used as inner doors. • If possible, factories should be designed not to have windows in food processing areas. If this is not possible, e.g. to allow visitor or management observation, windows should be glazed with either polycarbonate or laminated. A glass register, detailing all types of glass used in the factory, and their location, should be composed. • Metal or plastic frames with internal sills sloped (20º40º) to prevent their use as ‘temporary’ storage places and with external sills sloped at 60º to prevent bird roosting, should be used. • Opening windows must be screened in production areas and the screens be designed to withstand misuse or attempts to remove them. 360 Chilled foods
The hygienic design of chilled foods plant 361 LAOOOOOY Soffit sealed to wall ashing Cover detail Screed : 4∴:…:← Floor slab Fig. 13.3 Outside wall configuration showing a well sealed structure with elevated factory floor level 13. 2.3. High-risk production area It is unfortunate that the term high risk,, which is also used to describe other foods, for example low-acid canned foods, has become associated with the particular area of the factory where chilled foods are produced. The terms high risk areaand "low-risk area are often used to describe parts of a chilled foods factory where different hygiene requirements apply It is considered that such terminology is misleading, and its use can imply to employees and other people that lower overall standards are acceptable in those areas where, for example, operations concerned with raw material reception, storage and initial preparation are undertaken. In practice, all operations concerned with food production should be carried out to the highest standard Unsatisfactory practices in so-called low-risk areas may put greater pressures on barrier system'separating the two areas. Whilst undesirable, however, it is pable that such terminology will remain for the near future. The advent of the use of more 'pharmaceutical techniques in hygienic food manufacture may lead to the use of appropriate pharmaceutical terminology, e.g. clean'zones
13.2.3. High-risk production area It is unfortunate that the term ‘high risk’, which is also used to describe other foods, for example low-acid canned foods, has become associated with the particular area of the factory where chilled foods are produced. The terms ‘highrisk area’ and ‘low-risk area’ are often used to describe parts of a chilled foods factory where different hygiene requirements apply. It is considered that such terminology is misleading, and its use can imply to employees and other people that lower overall standards are acceptable in those areas where, for example, operations concerned with raw material reception, storage and initial preparation are undertaken. In practice, all operations concerned with food production should be carried out to the highest standard. Unsatisfactory practices in so-called low-risk areas may put greater pressures on the ‘barrier system’ separating the two areas. Whilst undesirable, however, it is probable that such terminology will remain for the near future. The advent of the use of more ‘pharmaceutical’ techniques in hygienic food manufacture may lead to the use of appropriate pharmaceutical terminology, e.g. ‘clean’ zones. Fig. 13.3 Outside wall configuration showing a well sealed structure with elevated factory floor level. The hygienic design of chilled foods plant 361
362 Chilled foods More recently, the Chilled Food Association in the UK(Anon. 1997a) established guidelines to describe the hygiene status of chilled foods and indicate the area status of where they should be processed after any heat treatment. Three levels were described, high-risk area(HRA), high-care area HCA)and good manufacturing practice(GMP). Their definitions were HRa An area to process components, ALL of which have been heat treated to >90%C for 10 mins or>70C for 2 mins and in which there is a risk of contamination between heat treatment and pack sealing that may present a food safety hazard HCA An area to process components, SoME of which have been heat treated to >70C for 2 mins. and in which there is a risk of contamination between heat treatment and pack sealing that may present a food safety GMP An area to process components, NoNE of which have been heat treated to>70C for 2 mins. and in which there is a risk of contamination prior to pack sealing that may present a food safety hazard In practice, the definition of HCa has been extended to include an area to further process components that have undergone a decontamination treatment e.g. fruit and vegetables after washing in chlorinated water or fish after low temperature smoking Most of the requirements for the design of HRa and HCa operations are the same, with the emphasis on preventing contamination in HRA and minimising contamination in HCA operations(Anon. 1997a). In considering whether a high risk or high care is required and therefore what specifications should be met. chilled food manufacturers need to carefully consider their existing and future product ranges, the hazards and risks associated with them and possible developments in the near future. If budgets allow, it is al ways cheaper to build to he highest standards from the onset of construction rather than try to retrofit or refurbish at a later stage. Guidance within this chapter is aimed at satisfying the equirements for high-risk operations Listeria philosophy In terms of chilled food product safety, the major contamination risk is microbiological, particularly from the pathogen most commonly lated with the potential to grow in chilled foods, Listeria monocytogenes. For many chilled food products, L. monocytogenes could well be associated with the raw materials used and thus may well be found in the low-risk area. After the product has been eat processed or decontaminated (e.g. by washing), it is essential that all measures are taken to protect the product from cross-contamination from low risk, L. monocytogenes sources. Similarly, foreign body contamination that would jeopardize the wholesomeness of the finished product, could also be found in low risk. A three-fold philosophy has been developed by the authors to help reduce the incidence of L. monocytogenes in finished product and at the same time control other contamination sources
More recently, the Chilled Food Association in the UK (Anon. 1997a) established guidelines to describe the hygiene status of chilled foods and indicate the area status of where they should be processed after any heat treatment. Three levels were described, high-risk area (HRA), high-care area (HCA) and good manufacturing practice (GMP). Their definitions were: HRA An area to process components, ALL of which have been heat treated to > 90ºC for 10 mins or > 70ºC for 2 mins, and in which there is a risk of contamination between heat treatment and pack sealing that may present a food safety hazard. HCA An area to process components, SOME of which have been heat treated to > 70ºC for 2 mins, and in which there is a risk of contamination between heat treatment and pack sealing that may present a food safety hazard. GMP An area to process components, NONE of which have been heat treated to > 70ºC for 2 mins, and in which there is a risk of contamination prior to pack sealing that may present a food safety hazard. In practice, the definition of HCA has been extended to include an area to further process components that have undergone a decontamination treatment e.g. fruit and vegetables after washing in chlorinated water or fish after low temperature smoking and salting. Most of the requirements for the design of HRA and HCA operations are the same, with the emphasis on preventing contamination in HRA and minimising contamination in HCA operations (Anon. 1997a). In considering whether a high risk or high care is required and therefore what specifications should be met, chilled food manufacturers need to carefully consider their existing and future product ranges, the hazards and risks associated with them and possible developments in the near future. If budgets allow, it is always cheaper to build to the highest standards from the onset of construction rather than try to retrofit or refurbish at a later stage. Guidance within this chapter is aimed at satisfying the requirements for high-risk operations. Listeria philosophy In terms of chilled food product safety, the major contamination risk is microbiological, particularly from the pathogen most commonly associated with the potential to grow in chilled foods, Listeria monocytogenes. For many chilled food products, L. monocytogenes could well be associated with the raw materials used and thus may well be found in the low-risk area. After the product has been heat processed or decontaminated (e.g. by washing), it is essential that all measures are taken to protect the product from cross-contamination from low risk, L. monocytogenes sources. Similarly, foreign body contamination that would jeopardize the wholesomeness of the finished product, could also be found in low risk. A three-fold philosophy has been developed by the authors to help reduce the incidence of L. monocytogenes in finished product and at the same time, control other contamination sources. 362 Chilled foods
The hygienic design of chilled foods plant 363 1. Provide as many barriers as possible to prevent the entry of Listeria into the high-risk area 2. Prevent the growth and spread of any Listeria penetrating these barriers during production 3. After production, employ a suitable sanitation system to ensure that all Listeria are removed from high risk prior to production recommencing 13.3 High-risk barrier technology The building structure, facilities and practices associated with the high-risk production and assembly areas provide the third and inner barrier protecting chilled the use of combinations of a number of separate components or sub-barriers, to control contamination that could enter high risk from the following routes product entering high risk via a heat process product entering high risk via a decontamination process. Product entering high risk that has been heat processed/decontaminated off-site but whose outer packaging may need decontaminating on entry to high risk other product transfer iquid and solid waste materials urfaces, usually associated with low/high-risk physical junctions and concerned with floors, walls, doors, and false or suspended ceilings food operatives entering high risk the air utensils, which may have to be passed between low and high risk 13.3. 1. Heat treated product Where a product heat treatment forms the barrier between low and high risk(e.g an oven, fryer or microwave tunnel), two points are critical to facilitate 1. All product passing through the heat barrier must receive its desired cooking time/temperature combination. This means that the heating device should be performing correctly (e.g. temperature distribution and maintenance are established and controlled and product size has remained constant)and that it should be impossible, or very difficult, for product to pass through the heat treatment without a cook process being initiate 2. The heating device must be designed such that as far as is possible, the device forms a solid, physical barrier between low and high risk. Where it is not physically possible to form a solid barrier, air spaces around the heating equipment should be minimised and the low/high-risk floor junction should be fully sealed to the highest possible height
1. Provide as many barriers as possible to prevent the entry of Listeria into the high-risk area. 2. Prevent the growth and spread of any Listeria penetrating these barriers during production. 3. After production, employ a suitable sanitation system to ensure that all Listeria are removed from high risk prior to production recommencing. 13.3 High-risk barrier technology The building structure, facilities and practices associated with the high-risk production and assembly areas provide the third and inner barrier protecting chilled food manufacturing operations from contamination. This final barrier is built up by the use of combinations of a number of separate components or sub-barriers, to control contamination that could enter high risk from the following routes: • product entering high risk via a heat process • product entering high risk via a decontamination process. Product entering high risk that has been heat processed/decontaminated off-site but whose outer packaging may need decontaminating on entry to high risk • other product transfer • packaging materials • liquid and solid waste materials • surfaces, usually associated with low/high-risk physical junctions and concerned with floors, walls, doors, and false or suspended ceilings • food operatives entering high risk • the air • utensils, which may have to be passed between low and high risk 13.3.1. Heat treated product Where a product heat treatment forms the barrier between low and high risk (e.g. an oven, fryer or microwave tunnel), two points are critical to facilitate its successful operation. 1. All product passing through the heat barrier must receive its desired cooking time/temperature combination. This means that the heating device should be performing correctly (e.g. temperature distribution and maintenance are established and controlled and product size has remained constant) and that it should be impossible, or very difficult, for product to pass through the heat treatment without a cook process being initiated. 2. The heating device must be designed such that as far as is possible, the device forms a solid, physical barrier between low and high risk. Where it is not physically possible to form a solid barrier, air spaces around the heating equipment should be minimised and the low/high-risk floor junction should be fully sealed to the highest possible height. The hygienic design of chilled foods plant 363
364 Chilled foods The fitting of heating devices that provide heat treatment within the structure of a building presents two main difficulties. Firstly, the devices have to be designed to load product on the low-risk side and unload in high risk. Secondly, he maintenance of good seals between the heating device surfaces, which cycle through expansion and contraction phases, and the barrier structure which has a different thermal expansion, is problematical. Of particular concern are ovens and the authors are aware of the following issues Some ovens have been designed such that they drain into high risk. This is unacceptable for the following reason. It may be possible for pathogens present on the surface of product to be cooked (which is their most likely location if they have been derived from cross-contamination in low risk)to fall to the floor through the melting of the product surface layer(or exudate n overwrapped product)at a temperature that is not lethal to the pathogen The pathogen could then remain on the floor or in the drain of the oven in such a way that it could survive the cook cycle. On draining, the pathogen would then subsequently drain into high risk Pathogens have been found at the exit of ovens in a number of food factories Problems have occurred with leakage from sumps under the ovens into higl risk. There can also be problems in sump cleaning where the use of high pressure hoses can spread contamination into high risk Where the floor of the oven is cleaned, cleaning should be undertaken in such a way that cleaning solutions do not flow from low to high risk. Ideall cleaning should be from low risk with the high-risk door closed and sealed. If leaning solutions have to be drained into high risk, or in the case of ovens that have a raining water cooling system, a drain should be installed immediately outside the door in high risk. Other non-oven related issues to consider include the following The design of small batch product blanches or noodle cookers (i.e. small vessels with water as the cooking medium) does not often allow the uipment to be sealed into the low/high-risk barrier as room ha created around the blancher to allow product loading and unloading Condensation is likely to form because of the open nature of these cooking vessels and it is important to ventilate the area to prevent microbial build-up where water condenses. Any ventilation system should be designed so that the area is ventilated from low risk; ventilation from high risk can draw into high risk large quantities of low-risk Early installations of kettles as barriers between low and high risk, together with the associated bund walls to prevent water movement across the floor and barriers at waist height to prevent the movement of people, whilst innovative in their time, are now seen as hygiene hazards. It is virtually impossible to prevent the transfer of contamination, by people, the air and via leaning, between low and high risk. It is now possible to install kettles within low risk and transfer product(by pumping, gravity, vacuum etc
The fitting of heating devices that provide heat treatment within the structure of a building presents two main difficulties. Firstly, the devices have to be designed to load product on the low-risk side and unload in high risk. Secondly, the maintenance of good seals between the heating device surfaces, which cycle through expansion and contraction phases, and the barrier structure which has a different thermal expansion, is problematical. Of particular concern are ovens and the authors are aware of the following issues: • Some ovens have been designed such that they drain into high risk. This is unacceptable for the following reason. It may be possible for pathogens present on the surface of product to be cooked (which is their most likely location if they have been derived from cross-contamination in low risk) to fall to the floor through the melting of the product surface layer (or exudate on overwrapped product) at a temperature that is not lethal to the pathogen. The pathogen could then remain on the floor or in the drain of the oven in such a way that it could survive the cook cycle. On draining, the pathogen would then subsequently drain into high risk. Pathogens have been found at the exit of ovens in a number of food factories. • Problems have occurred with leakage from sumps under the ovens into high risk. There can also be problems in sump cleaning where the use of high pressure hoses can spread contamination into high risk. • Where the floor of the oven is cleaned, cleaning should be undertaken in such a way that cleaning solutions do not flow from low to high risk. Ideally, cleaning should be from low risk with the high-risk door closed and sealed. If cleaning solutions have to be drained into high risk, or in the case of ovens that have a raining water cooling system, a drain should be installed immediately outside the door in high risk. Other non-oven related issues to consider include the following: • The design of small batch product blanchers or noodle cookers (i.e. small vessels with water as the cooking medium) does not often allow the equipment to be sealed into the low/high-risk barrier as room has to be created around the blancher to allow product loading and unloading. Condensation is likely to form because of the open nature of these cooking vessels and it is important to ventilate the area to prevent microbial build-up where water condenses. Any ventilation system should be designed so that the area is ventilated from low risk; ventilation from high risk can draw into high risk large quantities of low-risk air. • Early installations of kettles as barriers between low and high risk, together with the associated bund walls to prevent water movement across the floor and barriers at waist height to prevent the movement of people, whilst innovative in their time, are now seen as hygiene hazards. It is virtually impossible to prevent the transfer of contamination, by people, the air and via cleaning, between low and high risk. It is now possible to install kettles within low risk and transfer product (by pumping, gravity, vacuum etc.) 364 Chilled foods