The Application of HACCP to Mycotoxin Control – Initial Stages

Introduction

The application of HACCP principles to mycotoxin control is a relatively new approach, but is based on some very sound reasoning. As we have already discussed, HACCP is a management system designed to prevent problems from occurring, and there are some very good reasons why we should wish to prevent mycotoxin formation in the first place:

• Once formed, mycotoxins are relatively difficult to remove using available decontamination methods.
• There are significant problems associated with obtaining representative samples for mycotoxin analysis from large bulk stores*.
• Precise mycotoxin analysis is costly and often too slow to be of real use in many commodity chains*.

* Remember that ultimately, a properly conducted HACCP scheme largely takes away the need for extensive quality control type testing.

In principle, the stages in setting up a HACCP system for mycotoxin control in a particular product will be no different from those used in a conventional food processing situation. First of all, an appropriately experienced HACCP team will need to be appointed. After appointing the team, the product and the intended use of the product will need to be established. It will be important to understand the local socio-economic and climatic conditions involved in primary production, particularly where commodities are imported from developing countries. The mycotoxin hazard(s) themselves will normally be straightforward to establish. Next, the CFD itself will be developed. The knowledge required for risk assessment at each step in the CFD will be drawn from the expertise within the HACCP team, from published scientific data or from specially conducted surveillance studies and experiments. It is important to emphasise that every HACCP plan should be approached from first principles; a generic approach is unlikely to be adequate even for seemingly similar products.

Implicit in the preparation of a HACCP plan is the identification of the critical control points (CCP’s). In the case of a holistic approach addressing an entire commodity supply chain, the possible CCP’s may be very diverse in nature, and may cut across a number of areas of expertise.

The Pre-harvest and Harvest (Field) Situation

For some commodity and mycotoxin types, contamination is essentially a field event. Important examples of "pre-harvest mycotoxins" are the trichothecenes such as deoxynivalenol (DON) and T-2 toxin, produced by Fusarium moulds on growing cereal crops. Understanding mycotoxin contamination at this stage is therefore the realm of the agronomist, mycologist and plant pathologist, and experts in these disciplines will need to be part of the HACCP team.

It is important to note that many of the fungal infections that produce mycotoxins are also significant due to the crop damage (and losses) they cause (e.g. Fusarium ear blight), and control measures are often put in place for this reason alone. However, the significance of mycotoxins themselves is becoming widely recognized and is currently the subject of active scientific research, with much knowledge yet to be gained.

HACCP systems are sometimes perceived as being over-complicated and "difficult", and in the present case, where we are considering a holistic approach, this must be acknowledged as being a real danger. If we are to avoid a system that is too cumbersome to be of any real use we need some other systems to be in place before we begin. At the field stage the most important quality system is Good Agricultural Practice (GAP), which is a loose collection of codes of practice designed to ensure safe primary food production. GAP features in the Codex Code of General Principles on Food Hygiene (1997). Some aspects of GAP, together with related codes of practice, are published in the UK by DEFRA and the Health and Safety Commission. Most crop production in the UK is within some form of crop proficiency scheme, and these schemes will normally set down detailed GAP type principles to be followed in growing the crops. Examples of such schemes are the Assured Combinable Crops Scheme (England and Wales) and Scottish Quality Cereals (Scotland). The practical implication of the use of GAP within a HACCP scheme is that fewer CCP’s are likely to appear at the field stage. The following are examples of controls that will be within the remit of GAP, and therefore not necessarily CCP’s for the purposes of developing a HACCP plan:

• The use of fungus or pest resistant cultivars.
• Appropriate land preparation; crop rotation, trash removal, correct ploughing and fertilizer application.
• The control of insect and other pest damage (since this can encourage fungal infection).
• The control of fungal infection.
• The prevention of drought and weed stress.
• Harvesting at appropriate moisture content and stage of maturity.
• Appropriate handling and storage immediately after harvest.

It is important to stress that GAP is not designed to specifically prevent mycotoxin formation; the codes of practice are in place to provide healthy, sound plant material that is fit for purpose. Of course there are sound economic reasons for producing healthy crops, if only for the concomitant increased yields and value, and it follows that crops free from fungal infection are also free from mycotoxin contamination, Here again we return to the point that mycotoxin control often occurs as a result of the attention to control of more obvious fungal disease. However, with regard to mycotoxin contamination, there are some complications that fall outside of the scope of GAP. For example "improper" use of fungicides can in some instances lead to increased mycotoxin contamination. This may happen if the application of fungicide is not sufficient to quickly eliminate the infection, and the stressed fungus responds by producing increased quantities of mycotoxins. There is also evidence that some fungicides produce an increased mycotoxin response, even if the prescribed application methods are adhered to, although the evidence here is not clear at present. The result of these situations will be that apparently disease free crops may harbor high levels of mycotoxins, which will only be detected by specific analysis. In addition, as stated above, there is much yet to learn about mycotoxin formation in the field, so GAP cannot represent a complete answer to field stage contamination at present.

In some instances it will be appropriate to identify CCP’s at the field stage. This will normally be in situations where control steps are put in place that are specifically designed to prevent mycotoxin development. A number of examples of HACCP plans where CCP’s have been identified at the field stage are given below:

• Aflatoxin contamination in pistachio nut cultivation in S. W. Asia: The segregation and removal of visibly damaged nuts at harvest was considered a CCP, since damaged nuts are most susceptible to fungal attack and aflatoxin development. The step was therefore designed specifically to control mycotoxin contamination.

• Aflatoxin contamination in peanut cultivation for peanut butter manufacture in Southern Africa: Windrowing and sun drying of harvested peanut pods were both considered CCP’s since they were designed to bring the crop to a precise moisture level where aflatoxin development was not possible. Windrowing and sun drying is a two-stage process where the pods are first dried in heaps and then in thin layers on a flat surface. This combination allows the most rapid drying time without the use of drying equipment.

It is important to note that, when dealing with products originating in developing countries, certain control measures such as the use of expensive chemical treatments may not be possible, for socio-economic reasons. This further emphasizes the need for a thorough understanding of the constraints operating within a process before an effective HACCP plan can be established.

References

HACCP Manual for Mycotoxin Control. FAO/IAEA Training and Reference Centre for Food and Pesticide Control. Joint FAO/IAEA Division, Sweden.