Introduction to HACCP

The HACCP system is well established in safe food processing and manufacture worldwide, but is not usually implemented in the "early life" of food commodities, in particular the primary production and processing stages. In these articles we will be looking at the holistic application of HACCP to mycotoxin contamination, from "field to table". First of all, we need to introduce the HACCP process itself.

What is HACCP?

HACCP (Hazard Analysis Critical Control Point) is the name given to a system of controls specifically designed to prevent safety problems. It is normally applied to food manufacture, and represents a proactive system of preventive actions rather than a reliance on periodic inspection, end point testing and reactive responses to problems. It had its origins some 30 years ago in a collaboration between NASA, the Pillsbury company and the US army laboratories in a programme designed to ensure "absolute food safety" for US astronauts.

HACCP is often considered to be complicated, elaborate and over-bureaucratic, but is in fact a logical system, which requires only a sound understanding of the materials and processes relevant to a particular product. HACCP is also quite focused in that it is concerned only with food safety, and not food quality as a whole.

The HACCP system is composed of seven stages or "principles", which together describe the development and implementation of a complete HACCP plan. Before we outline the initial stages and principles it is necessary to define some of the terms we will be using.

Hazard: a property of a material, that may have a negative effect on human (or animal) health (in this instance by causing a food item to be unsafe). In HACCP generally we are able to identify three types of hazard:

• biological: e.g. the presence of pathogenic micro-organisms or their toxins.
• chemical: e.g. the presence of pesticide residues.
• physical: e.g. the presence of foreign materials such as glass or metal fragments.

Note that mycotoxins are usually classed as biological hazards because they are produced as a direct result of fungal growth at some point in the production system.

Risk: an estimate of the likely occurrence of a hazard.

Critical control point: a point in a process or system where loss of control may lead to an unacceptable health risk, or a point in a process or system where control can and must be applied to prevent a safety hazard.

Critical limit: the tolerance applied to a critical control, which describes the difference between a safe and an unsafe product. Critical limits are always a measurable quantity, such as temperature and time.

An example of a critical control point is the pasteurisation step in milk production, since this is designed specifically to destroy potentially dangerous microorganisms. The critical limits applied to this critical control are based on the measurable parameters relevant to the process (i.e. temperature and time), usually with a built-in "margin for error".

Initial Stages

The first stage in developing a HACCP scheme is to define the product and the intended use of the product. This will include a detailed description of the product, including customer specifications and the intended user groups. In the case of a holistic HACCP approach to food supply this may become complicated as a number of different "products" exist at various stages of the supply train.

The second stage in carrying out a HACCP plan will be to appoint a HACCP "team". In conventional food manufacture this team will typically comprise of management, technical, scientific and production staff, so that all aspects of the production system are represented. In the case of a HACCP approach to mycotoxin contamination at all stages of food production, an effective HACCP team for a particular commodity may comprise agronomists, microbiologists, mycotoxicologists, and experts in farming, distribution, process engineering, etc. It is the role of the HACCP team to devise the HACCP plan, to implement and verify it, and to produce and maintain all the relevant accompanying documentation.

The Seven Principles of HACCP

Principle 1:

Conduct a hazard analysis. Prepare a list of steps in the process where significant hazards occur and describe the preventive measures.

This may sound simple enough on paper, but is probably the most crucial part of any HACCP plan, and will dictate how effective the entire plan will ultimately be. To conduct a comprehensive hazard analysis requires a thorough knowledge of the relevant supply or production system. In the case of conventional food manufacture, this normally involves preparation of a "Process Flow Diagram"(PFD), which describes in detail all stages in the production process. We are concerned here with mycotoxin occurrence in foods at all potential points in production and supply, so we will be discussing "Commodity Flow Diagrams" (CFD) involving, in particular, primary production, storage, transport and processing steps. CFDs are made complex by the nature of commodity supply itself, which is often intricate, the products typically passing through the hands of a number of "owners" en route (farmers, transporters, merchants, processors, etc).

Assuming that we have been able to delineate an accurate, detailed CFD for the relevant commodity, our next task is to conduct the hazard analysis itself. In the case of mycotoxin contamination, the inherent hazards are relatively easy to identify. The toxic nature of most of the important mycotoxins are discussed in other areas in the Web site. In the case of certain mycotoxins (e.g. aflatoxins), legislative limits already exist in some countries for their presence in various food substances, and limits are likely to be introduced for more mycotoxins in the future. In addition, the relative risk of a particular mycotoxin affecting a certain type of commodity is usually straightforward to establish since a large amount of established data is available. For example, the EU specifies products susceptible to aflatoxin contamination in the EC aflatoxin regulations. Some products and materials will be subject to a customer specification, which will specify acceptable levels of particular mycotoxins. However, for certain commodities, data may be lacking on mycotoxin risk, and in these instances mycotoxin analysis and surveillance of the commodity will be necessary.

Having established the mycotoxin hazard, the next step is to carry out a hazard and risk analysis at each step in the CFD. Of course, identification of all risk factors when dealing with a complex CFD can be a very difficult task. The perception of risk in particular is an area where knowledge and experience are essential. Often, expert opinion will need to be sought outside of that which is available within the HACCP team, and experience with similar materials and products will sometimes need to be sought. The best advice on assessing risk seems to be: if there is doubt about the significance of a hazard, assume that there is a significant hazard and build controls around it.

A CFD that is sufficiently detailed to be of real use is likely to be very specific to the commodity type, product type, and the relevant country or climatic zone of production. A "typical" CFD will include a multitude of stages, including land preparation, growing, harvest, drying, transportation and specific processing. Each of these can influence the risk of mycotoxin contamination in the final product. The type of mycotoxin contamination under consideration will also have an important bearing since this will dictate the most likely point of entry into the system. For example, mycotoxins such as the trichothecenes, produced by the Fusarium species of fungi, invariably affect the pre-harvest crop (e.g. wheat), whereas aflatoxins can be produced in a number of crop types both pre- and post-harvest (e.g. during storage). The occurrence and control of mycotoxins in the commodity supply chain are a large area for discussion, and will be the subject of further articles and examples.

Having carried out a comprehensive risk assessment, we are ready to move onto the next stage.

Principle 2:

Determine the critical control points (CCP).

We have already defined CCPs as points in a process where control can and must be applied to control a hazard. The designation of CCPs itself requires careful consideration. In particular, CCPs should be kept to a minimum to prevent the overall system from becoming over-complicated. Remember that HACCP is concerned with safety, not quality, so controls that do not impinge on safety are not CCPs for the purposes of HACCP. In addition, CCPs must always have a quantifiable element that is measurable in real time, so that critical limits (Principle 3) can be applied to them.

The process of designating critical control points will involve careful consideration of each step in the CFD for the identified hazard. If control measures exist at the step in question, and if the hazard is best controlled at this step, then this probably represents a CCP. If the hazard exists at a particular step, and no control exists at this step or subsequently, the commodity is unsafe for use, and controls must be designed and implemented. In practice, the designation of CCPs is normally aided by the use of "decision trees". An example of a decision tree, adapted from Codex Alimentarius, is given below.

Critical Control Point decision tree

A Critical Control Point decision tree (adapted from Codex Alimentarius, 1993) - see above

In principle, the CCP decision tree helps to identify the steps that are subject to the hazard under consideration, and most importantly helps to identify the key steps where controls must be implemented (Q. 4. in Fig. 1). Q. 3. in Fig.1. is mainly concerned with processing or manufacturing steps and the relevant environment. For the purposes of mycotoxin contamination it will have relevance to the post-harvest situation, and the possibility of contamination during processing and storage.

Principle 3:

Establish Critical Limits.

The critical limits are the measurable parameters, attached to every CCP, which will ensure that control is maintained. In the case of mycotoxins, they will include the permissible moisture and temperature targets for safe storage of grain. These parameters will typically incorporate a margin of safety to allow for instrumental and operator error.

Principle 4:

Establish Procedures for Monitoring the CCPs.

Monitoring is one of the most important aspects of the HACCP approach, as it is this that ensures that the CCPs remain under control. In spite of this, the meaning of monitoring is often misinterpreted in the context of HACCP. Monitoring needs to be both precise and rapid, and this is especially true of the cereal supply chain, which often operates on a very fast, "just in time" basis. Monitoring systems attached to CCPs are therefore restricted to the simplest of checks, such as grain moisture level that can be performed in "real time". Therefore, mycotoxin analysis itself can seldom be used as a means of monitoring for HACCP purposes because of the time delay in obtaining a result. Only the semi-quantitative rapid test kits are potentially useful in a monitoring role. In practice, for grain quality, monitoring can also be carried out by direct observation, e.g. assessment of the degree of moulding or damage, which may be an important criterion in both the pre- and post-harvest situations. Effective monitoring of grain commodities involves obtaining truly representative samples from large bulk stores. This is an important issue within the industry.

Principle 5:

Establish Corrective Actions.

For each CCP, corrective actions need to be devised in a situation where monitoring reveals that critical limits are not being achieved. Corrective actions must be designed to bring the CCP back under control as quickly as possible. There must also be procedures in place to handle material that may be affected by the loss of control. In the case of mycotoxin contamination, material suspected to be subject to control failure (e.g. as a result of storage at an inappropriate moisture content) will be segregated pending mycotoxin analysis. This is an example of an area where rapid mycotoxin assay kits play an important role. Subsequent treatment will then depend on the severity of contamination, and may include discarding, down-grading or re-processing. The corrective action applied to the process will depend on the nature of the failure, and may include equipment repairs or changes to storage or drying conditions.

Principle 6:

Establish verification procedures.

On completion of the HACCP plan, verification is required to establish that appropriate control is being maintained. In the case of HACCP for mycotoxins, this is another area where mycotoxin analysis itself will be required. If mycotoxin levels are found to be above the required levels, then immediate action is required to identify the step(s) where adequate control is not being maintained. This may involve the introduction of new CCPs, or amending critical limits for existing CCPs.

Principle 7:

Establish documentation and record keeping.

The preparation of suitably detailed and comprehensive procedural and record keeping documentation is of paramount importance for the running of a successful HACCP scheme. The application of a holistic HACCP plan for mycotoxin control in an entire commodity supply train will inevitably involve complex and extensive documentation.

Documentation will typically include the original CFD, the accompanying hazard and risk assessment and the identification of CCPs and critical limits. Other working documents will include the monitoring procedures and corrective actions, written in such a way that they can be used as operating instructions by relevant personnel. Implicit in this will be detailed on-going record keeping of monitoring results. Verification procedures and results will also form part of the documentation.

This concludes our overview of the HACCP procedure. Future articles will look in more detail at how HACCP can be applied to mycotoxin control for a number of commodity types.

References

Codex Alimentarius Commission (1993). Codex Guidelines for the Application of the Hazard Analysis Critical Control Point (HACCP) system. Joint FAO/WHO Codex Committee on Food Hygiene. WHO/FNU/FOS/93.3 Annex II.