HYGIENE BY DESIGN

| May 21, 2008

Contaminated food processing equipment has been responsible for a number of major food poisoning outbreaks over the years, not to mention innumerable cases of product spoilage and quality defects. In some cases these events are the result of a failure to maintain, clean, or operate the equipment hygienically, but in others the fault can be found in the basic design of the equipment itself. Components that cannot be properly cleaned, or parts of a processing plant that fill with liquid product, but never completely drain, are still far too common and can cause continual contamination problems. Fortunately, great strides have been made in hygienic equipment design recently, at least partly due to the efforts of organisations like the European Hygienic Engineering and Design Group (EHEDG).

In 2000 an outbreak of Staphylococcus aureus food poisoning affected around 14,000 people in Osaka, Japan. The culprit was found to be contaminated skimmed milk from a plant in Hokkaido operated by Snow Brand Foods. The facts about how such widespread contamination was allowed to occur are still the subject of debate, but one contributing factor seems to have been a dirty valve fitted to a milk storage tank at the plant. Staph aureus bacteria were isolated from this valve, and this seems to have been a major source of contamination. Coupled with haphazard hygiene practices and poor GMP, the result was one of largest food poisoning outbreaks ever recorded and culminated in the winding up of Snow Brand Foods itself. This event served as a salutary example of how small piece of equipment, such as a single valve, can be a cause of potentially catastrophic contamination problems for a food manufacturer.

Such ruinous situations can be prevented in part by responsible operation, effective cleaning and by applying HACCP principles to the process, but this is only part of the story. A processor faced with operating equipment that has not been designed with hygiene and cleaning in mind is faced with a very difficult job in preventing product contamination. Many man-hours are likely to be wasted in needlessly stripping down pumps, valves, pipes and complex machinery so that potential bug traps can be accessed and cleaned properly. More thought at the design stage could avoid these problems and arrive at a plant that is easy to clean and does not need to be dismantled on a regular basis to prevent contamination. This seems obvious, but most hygiene auditors have an extensive fund of anecdotes about plant and equipment they have seen that seemed almost designed to harbour contamination. Long lengths of pipe forming ‘dead ends’, in which product can remain static for long periods allowing microorganisms to multiply, pumps and tanks that cannot be drained without dismantling, valves that always retain small quantities of product residue behind seals or in joints, even equipment adapted from non-food applications and constructed using entirely inappropriate methods. All of these can still be found in food factories and are a potential source of microbial contamination problems.

An example of poor hygienic design

hygiene pic

A stirrer immediately after cleaning
 

Hygiene pic 2

The same stirrer revealing the contaminated product residue trapped between the shaft and the stirrer boss
 

(Images kindly provided by Burggraaf & Partners B.V. www.burggraaf.cc)

As with most food safety issues today, EU law has something to say on the subject of hygienic design of equipment that comes into contact with food. The new food hygiene Regulations, which came into force in January 2006, state that such equipment is to be “so constructed, be of such materials and be kept in such good order, repair and condition as to minimise any risk of contamination.” Furthermore, food processing equipment is to be “so constructed, be of such materials and be kept in such good order, repair and condition as to enable them to be kept clean and, where necessary, to be disinfected.” This is pretty clear as a general principle, but it is not prescriptive and is open to varying interpretations. Food processing equipment currently on the market will certainly claim to meet these requirements, but just how well is a matter for expert judgement and is not so easy to assess. There is clearly scope for some type of self-regulation scheme for food processing equipment manufacturers. Fortunately such a scheme exists in the form of the European Hygienic Engineering and Design Group, or EHEDG.

EHEDG sets the standard

EHEDG was founded in 1989 as a consortium of equipment manufacturers, food companies, research and academic institutes and public health authorities with a common purpose of promoting hygiene during food processing and packing. The main aim of the consortium is to promote safe food by working to improve hygienic engineering and design across all aspects of food manufacturing. The scope of EHEDG work covers not only the design and cleanability of equipment, but also of buildings. It also focuses on equipment and building installation, industrial services and utilities and the maintenance of assets. Financial support comes from the contributions of member companies based on turnover and the membership fees of individual members. EHEDG has also received support from the EU in the past, notably through the European Network for Hygienic Manufacturing of Food (HYFOMA) thematic network. Despite this, the voluntary contributions of many EHEDG members are a vital component of the consortium’s activities.

The main outcome of EHEDG activities has been the publication of more than 30 guidelines providing practical advice for equipment manufacturers and food processors on the application of hygienic design principles in various types of equipment. These range from an overall outline of hygienic equipment design criteria to specific guidance on welding stainless steel to meet hygiene requirements and the design of valves for food processing applications. More guidelines on topics such as conveyors and chilling equipment are in production, and the Group plans to publish four to five new guidelines each year. EHEDG has also produced a number of test methods for assessing the cleanability of food processing equipment. The guidelines and methods are developed by expert working groups drawn from the membership of subgroups within the organisation’s committee structure.

There are currently four subgroups covering the following topics.

    • Equipment and components: conveyors, cooling and chilling, fish/meat processing equipment, mechanical seals, packing machines, pipes and couplings, pumps, sensors and valves
    • Principles: building design, design principles, dry material handling, hygienic systems integration, construction materials, testing/certification, welding
    • Processing, services and utilities: air handling, electrical installations, heat treatments, lubricants, process water
    • Training and Education: facilitator, toolbox, training

Originally published in English, EHEDG publications are now available in several European languages and these can be ordered from local agents. The guidelines have also been used to develop a ‘Training Facilitator’ – effectively a syllabus of themed training modules, complete with training objectives for various target groups. Together with a ‘Training Toolbox’ of DVDs and CD-ROMs full of practical examples and applications, the Facilitator is used as the basis for a programme of practical training courses in basic hygienic design run regularly for designers and engineers involved in building food processing equipment. The courses often involve interactive case studies focusing on real equipment in a pilot-plant setting.EHEDG recognises the importance of collaboration on hygienic equipment design with other bodies outside Europe. For example, agreement has been reached with US-based organisations NSF and 3-A to co-operate on the development of harmonised guidelines and standards. The consortium also feeds information and suggestions into the development of international standards, such as ISO 14159:2002 Safety of Machinery – Hygiene requirements for the design of machinery.The other main area of activity for EHEDG is controlling the use of its name and logo. Some years ago the organisation became concerned that some manufacturers were using the EHEDG logo in promotional material for equipment without permission. In many cases the equipment concerned did meet hygienic design criteria, but in other cases it most certainly did not. So, to protect the integrity and reputation of the EHEDG name, a certification scheme for food processing equipment was set up.

Now, in order to use the logo in connection with a piece of equipment, a manufacturer must submit clear evidence, including detailed drawings and the results of laboratory tests conducted using EHEDG methods, that the equipment does comply with the hygienic design criteria. That evidence will then be assessed by qualified experts, who are employed by one of the four organisations authorised to provide EHEDG certification, and who then prepare an evaluation report. If the report is satisfactory, the manufacturer can use the certification logo on the equipment, subject to certain conditions set out in a formal contract. There are currently four authorised certification bodies in Europe, CCFRA in the UK, the Danish Technological Institute, TNO in the Netherlands and TU München in Germany.

This scheme has proved to be very successful since its introduction and has helped manufacturers to demonstrate that their equipment complies with good hygienic design principles. Food processors also find the scheme helpful when sourcing properly designed equipment. There is now an extensive list of certified equipment and components from a range of manufacturers, suitable for a wide range of applications, and the EHEDG logo is now seen as a valuable marketing tool.

The work of EHEDG has gone some way towards eliminating poorly designed processing equipment from the market and has provided a supporting structure to help the industry design and market equipment that complies with best practice in hygienic design and operation. There is now no good reason for any food processor to use poorly designed equipment and components when putting together a new production line, or equipping a new factory. Of course, there is still a lot of older equipment in use that does not meet modern hygiene standards. It is very difficult to modify such equipment so that it complies with current standards if it has not been designed using hygienic principles. In many cases, it may be less expensive in the long term to scrap old equipment and replace it with easy-to-clean modern alternatives.

Factory layout crucial for hygiene

While EHEDG may have helped to drive great improvements in the hygienic design of food processing equipment, one important hygiene factor that has lagged behind is the design and layout of the food factory itself. Much of the benefits of installing equipment designed and manufactured to modern hygiene standards can be lost if that equipment is crammed into an inadequate space so that it is difficult to access for cleaning and maintenance. Even quite recently constructed food factories can suffer from accessibility problems and contain areas where waste and dirt accumulate because they are so difficult to get at for cleaning. EHDEG has addressed this problem to some extent for factories handling dry materials, but even so, there is no certification available for factory layout.

As with equipment, EU legislation includes requirements for the layout and design of premises, which are to “permit adequate maintenance, cleaning and/or disinfection, avoid or minimise air-borne contamination, and provide adequate working space to allow for the hygienic performance of all operations.” Once again this requirement is open to varying interpretations and authoritative guidance and training on factory design and layout would be a significant benefit. While industry hygiene standards, such as the BRC global and EFSIS standards, have helped to improve factory design, especially in high-risk sectors, there could be a place for an extension to EHEDG concerned with providing guidance and training for those responsible for designing food factories. This would be especially valuable for developing countries supplying foods to a global market.

If workable standards for factory design and layout can be established, it will at last be possible to get rid of some of the almost Dickensian factory environments that can still be found in some sectors of the food industry. The result will be better working conditions for employees as well as improved food safety and quality.

More information about EHEDG can be found on the organisation’s web site .

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