Example 3: Copra cake and meal - Southeast Asia

Introduction.

Coconut oil is produced by extracting oil from copra, which is dried coconut flesh. When the oil is expelled mechanically the residue is called copra cake and if this is then solvent extracted to increase the yield of oil, the product is called copra meal. These copra by-products are valuable protein sources in animal feeds, especially dairy feed. In the early 1990s the European Union tightened aflatoxin B₁ regulations on dairy feed to 5 µg/kg and also reduced the limit for aflatoxin B₁ in copra by-product to 20 µg/kg. This action put the vitally important export market for copra by-product in jeopardy. Loss of the market, worth US$ 80 million to one country in Southeast Asia alone, would have made many of the oil mills non-viable and would have caused great hardship to millions of coconut farmers.

A HACCP-type approach was used to try to save the European market by increasing very substantially the number of batches meeting the new regulations and by raising confidence in the product in Europe. The findings of the associated research (Andanar, W., 1991 & Anon., 1993) have been used as a basis for this example.

Task 1 - The HACCP team

An appropriate HACCP team will be composed of: a HACCP specialist, a mycotoxicologist, an oilseeds specialist, a socio-economist, a mycologist, a drying engineer, and representatives of the coconut oil industry from both the public and private sectors.

Tasks 2 and 3 - Product Description and Intended Use, Verified

This information is given in Table 7.

Tasks 4 and 5 - The Commodity Flow Diagram (CFD), Verified

The CFD will be established using information provided by the HACCP team, and will be verified by visiting major copra production centres and oil mills and interviewing key players and observing their practices. An example of a typical commodity flow diagram is given in Figure 10.

Table 7. Product description and intended use for Example 3.

Target level: £ 20 µg/kg aflatoxin B₁

Task 6: Mycotoxin hazard analysis and identification of possible control measures.

Hazard Analysis

a). Identification of mycotoxin hazard

Aflatoxin is the only mycotoxin hazard for which regulatory limits have been set to protect animal health and production, and also to ensure that levels of aflatoxin M₁ (a metabolite of aflatoxin B₁) in milk are within a very strict limit of 0.05 µg/Litre.

Figure. 10. Verified commodity flow diagram for Example 3.

b) Identification of steps in the Commodity Flow Diagram (CFD) where mycotoxin contamination is most likely to occur.

Surveillance studies and controlled experiments were undertaken to determine at which steps aflatoxin contamination was most likely to occur. It was found that aflatoxin was produced within 10 days of splitting the coconut, when the coconut meat was at a water activity of >0.82, and aflatoxin producing moulds could grow. This situation occurred during the drying process, at steps 3 (on the farm) and/or step 4 (at the Primary Trader). Levels of aflatoxin were always zero prior to splitting, provided that the nut was sound. If the nut had been split prematurely, during harvest or de-husking, then these nuts could be contaminated prior to drying. Reject nuts from the desiccated coconut industry were often prematurely split and represented a special case.

Risk of aflatoxin contamination was low in subsequent steps, apart from Step 7 where pellets could be produced at too high a moisture and be susceptible to mould and mycotoxin contamination.

c) Possible Mycotoxin Control Measures

Drying uniformly to a 'safe' moisture content within 48 hours of splitting the nut was found to be by far the most important control measure.

Surveillance studies strongly indicated that traditional smoke drying was correlated with low-aflatoxin copra.

Average levels of aflatoxin in sun-dried copra were found to be very high. This was mainly because four or five full days are required to attain the 'safe' moisture content and farmers usually only dried for 2 or 3 days. Lengthening the drying time was not a complete solution because the copra could easily still be in the 'unsafe' moisture content window for >48 hours and contamination could occur during drying. Also this scenario assumes perfect sun-drying weather. If drying is slowed by cloudy weather, or interrupted by rain, then there is a very high risk that high levels of aflatoxin B₁ will result. Therefore, discouraging sun-drying was considered a control measure.

An incentive was required for farmers and traders to produce low-aflatoxin copra. This was provided in an amended Government grading scheme which introduced grading on the basis of percentage yellow-green mould. It also increased the premiums for dry copra, so that it made it worthwhile to dry to a 'safe' moisture content.

Tasks 7 to 10: Development of a HACCP Plan

A spreadsheet summarising the HACCP Plan for copra by-product is given in Table 8. The development of the plan at each step in the CFD is given below.

Step 1: Farm, harvesting and dehusking - CCP1

This step was classified as a critical control point with a control measure to eliminate the use of nuts found to be split during harvesting and dehusking. This CCP would eliminate any aflatoxin already present.

The critical limit will be set at zero cracked nuts and it will be monitored by trained harvesters or de-huskers. The CCP can be validated by determining the aflatoxin content of batches of accepted nuts.

Step 2: Farm, splitting nuts - GAP

Coconuts are split into halves, or sometimes smaller pieces, immediately prior to drying. It is advisable to ensure that the coconut meat is protected from contact with soil, which is a rich source of inoculum. This is considered GAP.

Step 3: Farm, drying - CCP2

This was classified as a CCP with drying to a safe moisture content within 48 hours being the control measure. This CCP will prevent the growth of mould and production of aflatoxin.

Controlled drying and storage trials showed conclusively that direct smoke drying protected copra from aflatoxin contamination: copra only needed to be dried to a moisture content of £16% to store safely, whereas hot-air dried or sun-dried copra needed to be dried uniformly to £12% to prevent aflatoxin contamination. These moisture parameters are achieved by setting critical limits on the drying time. Different types of dryer will require different drying times, and different copra turning schedules, to achieve the safe moisture content. For example, smoke drying will take 24 hours with turning of copra cups every 8 hours, whereas a commonly used hot-air drier will take 30 hours, with a change in bed position every 10 hours.

The critical limits are monitored by timing the drying period and the scheduled turning or moving of the copra on the drying bed. Validation of the CCP will be achieved by measuring the moisture content of the product.

Step 4: Primary trader, procurement and drying - GMP/GSP

A national grading system, which provides a premium price for Grade 1 copra showing <1% yellow-green mould (characteristic of Aspergillus flavus or A. parasiticus which produce aflatoxin) and meeting a 12% moisture limit, was introduced. It is considered GMP for Primary traders to purchase grade 1 copra, and keep it separate from lower grade copra.

Primary traders currently also purchase lower-grade copra, at moisture contents up to 18%. They purchase this at a lower price and then dry to 12% moisture. This practice often leaves copra at an unsafe moisture content for longer than 48 hours and results in a greatly increased risk of mould and aflatoxin contamination.

Primary traders store dried copra for a short period, whilst they accumulate sufficient to sell to a Secondary trader. Good storage practice will ensure that the copra remains dry.

Step 5: Secondary traders, procurement and storage - GMP/GSP

Procurement of Grade 1 copra is also GMP at this step. The Grade 1 copra must be kept separate from other grades and marketed as low-aflatoxin copra.

Good storage practice, such as palleted storage in a store with good ventilation and a sound roof, will prevent re-wetting and subsequent contamination with mould and aflatoxin (Head, S. W., 1999).

Lower grade copra will dry in store and successive colonies of moulds will grow until the safe moisture content of 12% is reached. The copra no longer looks mouldy at this stage, and there is certainly no sign of yellow-green mould. However, such copra retains pitting of the surface associated with penetrating moulds and can be identified in this way.

Step 6: Oil mills, procurement - GMP

Procurement of Grade 1 copra is essential to produce copra by-products containing acceptable levels of aflatoxin, and this is considered to be GMP. It should be noted that the mould classification now includes copra that is pitted.

Oil millers tend to buy and store large stocks of copra. Provided that the copra is at, or below, a moisture content of 12%, then aflatoxin will not be produced with good storage practice in place. It is important to have adequate aeration, however, because 'hot spots' can develop and these can even result in spontaneous combustion.

Step 7: Oil mill, expelling/extracting/pelleting - CCP3

No aflatoxin control measures are necessary during expelling of oil and solvent extraction. In fact the high temperatures present during expelling will sterilise the copra meal, destroying mould spores and hence reducing the risk of subsequent contamination.

The pelleting process within Step 7 was classified as a CCP, with a critical limit of 12% moisture in the cooled pellets. Insufficient cooling, or insufficient aeration of the pellets will result in an unacceptable moisture content. For a given process, the critical limits will be the dwell time in the cooling tower and the air-flow. These critical limits will be monitored by timing the dwell time and measuring the air-flow. The CCP will be validated by regularly determining the moisture content of the cooled pellets.

Pelleted copra by-product is stored either in bags or in bulk until shipment is possible. Good storage practice will prevent any subsequent aflatoxin contamination.

Step 8: Shipment - GMP/GSP

No increase in aflatoxin contamination is likely during shipping, provided that the copra by-product is loaded at a moisture content of £ 12%, and does not suffer sea-water damage. Practices, such as opening holds during fine weather will help reduce further any risk of mould damage.

A number of shipments of copra by-product were closely monitored, and no increase in aflatoxin levels were found.

Task 11: Establish verification procedures

Validation procedures will be established for each of the CCPs, as indicated above, and overall verification will be provided by the fully quantitative aflatoxin results on the pre-loading samples, taken immediately prior to export.

The HACCP Plan will be audited quarterly and amended as necessary.

Task 12: Establish documentation and record keeping

The HACCP Plan will be fully documented, including appropriate records at the farmer and Primary trader steps.

Table 8. HACCP Plan Worksheet, Copra By-Product in Southeast Asia

References

Andanar, W. (1991). 'Improvements in coconut growing and processing methods in the Philippines'. CBI News Bulletin 180 23-4

Anon. (1993). 'Aflatoxin project in the Philippines' Cocomunity 23, 6.

Head, S. W., Swetman, A. A., Nagler, M. J. (1999). 'Studies on deterioration and aflatoxin contamination in copra during storage'. OCL 6 (3)