Example 4: Commercially produced peanut butter, Southern Africa

Introduction

The commodity system represented here is similar to those systems frequently found in sub-Saharan Africa, where the small-scale production of groundnuts is practised in combination with the commercial manufacture of peanut butter.

Small scale commercial or peasant farmers' crops are usually short-season, low-input cultivars (cvs) which are intended to be grown within the rainy season, without irrigation. Short season cvs are often more resistant to aflatoxin production than long-season cvs.

Peanut butter is produced from groundnut kernels by roasting, grinding and mixing processes. Emulsifiers are added to ensure that the oil released by grinding remains in suspension. Groundnut processing systems are very complex, involving a variety of manufacturing lines producing differently specified products; a single product line is considered in the current example.

Task 1 - The HACCP team

The HACCP team will include: HACCP specialist, production manager, factory quality assurance manager, mycologist, mycotoxicologist, commodity specialist, socio-economist, agronomist and representatives of trading and export sectors

Tasks 2 and 3 - Product description and intended use

Table 9 shows the product description and intended use.

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

The CFD was established and verified and is summarised in Figure 11

Table 9. Product Description and Intended Use of End Product

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 the region has regulatory limits for groundnuts and, consequently, it is the only mycotoxin considered. It is also the key mycotoxin associated with groundnuts.

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

Step 1: On farm, pre-harvest

Pre-harvest contamination with aflatoxin-producing Aspergillus moulds is associated with drought stress and insect damage, both of which are difficult to control without access to irrigation and expensive insecticides. Insect damage provides an entry point for mould propagules, which are often carried by the insect itself. Drought stress can also cause pod splitting in the soil, leaving the kernels exposed to the soil microflora.

Fig. 11. HACCP Flow-diagram: Peanut Butter in Southern Africa

Steps 2: On-farm harvesting

Additional contamination with Aspergillus moulds is unlikely during the harvesting process.

Steps 3 & 4: On-farm, windrow and sun-drying

Contamination by Aspergillus moulds will occur at these steps if a 'safe' moisture level is not achieved within a short period of time.

Step 5: On-farm, removal of pods from haulm

Additional contamination with Aspergillus moulds is unlikely during the removal of the pods from the groundnut haulm.

Steps 6-8: Farm to trader or processor

No aflatoxin contamination should occur here, if the commodity is properly stored and handled.

Step 9: At factory, aflatoxin testing of incoming batches of groundut kernels

There is no risk of additional contamination at this step.

Step 10: At factory, roasting

There is no risk of additional contamination at this step.

Step 11: At factory, hand-sorting

There is no risk of additional contamination at this step.

Steps 12 & 13: At factory, grinding and packing

There is no risk of additional contamination at this step.

c) Possible Mycotoxin Control Measures (Table 10)

If pre-harvest contamination is to be avoided, the most effective control measures will involve those procedures associated with GAP, which prevent mould contamination. Such control measures will include the prevention of drought stress and insect damage, the use of fungal-resistant varieties (if available), the use of fertilisers and the control of weeds. The use of biological control agents such as atoxigenic strains of Aspergillus flavus has been piloted in the USA and Australia, but has not, as yet, been widely adopted as a fully acceptable practice.

Immediately after harvest, it is essential that the groundnuts are dried to a 'safe' moisture level (a_w £ 0.82) as rapidly as possible. Artificial drying procedures are not generally available in southern Africa, where sun-drying is normally performed on the haulm, by a combination of windrow drying followed by drying on a flat surface.

A further control measure is the segregation of contaminated nuts during harvesting, drying and handpicking. The ultimate segregation procedure is the inspection of individual batches of groundnuts, by sampling and aflatoxin analysis, and the rejection of excessively contaminated batches.

Tasks 7-10 - Development of a HACCP Plan

A worksheet summarising the HACCP Plan for peanut butter is given in Table 10

Step 1: On farm, pre-harvest - GAP

GAP will prevent pre-harvest mould contamination, although the effects of inclement weather (drought stress, prolonged rains) can be extremely difficult, if not impossible, to control.

Steps 2: On-farm harvesting - GAP

Again, GAP will prevent pre-harvest mould contamination. The selection of the appropriate harvesting time is important so that the groundnuts are harvested immediately they reach maturity. It is also important that the pods are not damaged during harvesting, in order to maintain a protective environment for the groundnut kernels.

Steps 3 & 4: On-farm, windrow and sun-drying - CCP1 and CCP2

These steps are both CCPs, since mould and aflatoxin contamination will rapidly occur if the groundnuts are not dried to a safe moisture level (a_w £ 0.82) as rapidly as possible. The precise combination of moisture level and maximum permitted drying period will vary with groundnut variety and agroclimatic zone, and will need to be determined using local knowledge. It is envisaged that the preliminary windrow drying should achieve a moisture level of £ 12%, whereas the second drying phase, on a flat surface, should attain a £ 7% moisture level. However, mould and aflatoxin contamination can still occur if the safe moisture levels are not attained sufficiently rapidly.

Step 5: On-farm, sorting during removal of pods from haulm - CCP3

The control measure is the rejection of pods which are discoloured, mouldy and/or damaged whilst the pods are being removed from the haulm. The critical limit will be determined by the maximum percentage of unacceptable pods which, typically, can be removed during the harvesting process. For the purposes of this example it is assumed that 95 per cent of unacceptable pods could reasonably be expected to be removed during harvesting.

Steps 6-8: Farm to trader or processor - GAP

The careful storage and handling of both the pods and the kernels is classified as GAP and GMP. However, it is essential that the groundnuts are maintained in a clean, dry and undamaged state during these steps, if contamination is to be avoided.

Step 9: At factory, aflatoxin testing of incoming batches of groundut kernels

Step 9 is a CCP which segregates those batches of groundnuts which contain an unacceptable level of aflatoxin B₁. The aflatoxin content of every batch of groundnut kernels is determined by selecting a representative sample of 20kg, at least, and analysing for aflatoxin using a simple, semi-quantitative test kit. (More sophisticated analytical methods such as high performance liquid chromatography, HPLC, may be used, of course, if available.) The critical limit will be an acceptable level of aflatoxin B₁ which, after the implementation of steps 10 and 11, will allow the target level of 20 mmg/kg aflatoxin B₁ to be attained. In this example, the HACCP team considered that the critical limit should be 30 mmg/kg aflatoxin B₁.

In a situation where it is felt that pre-harvest contamination is under control, or is not a significant problem, Step 9 may eventually be utilised as a component of the verification procedure.

Step 10: At factory, roasting - GMP

The roasting of the groundnut kernels under appropriate conditions is considered as GMP. However, the roasting process can cause a 20-30% reduction in aflatoxin contamination, depending upon the operating conditions utilised.

Step 11: At factory, hand-sorting - GMP

The primary aim of the hand-sorting process is the removal of burnt kernels, which will have a detrimental effect on the quality of the peanut butter. However, Step 11 also provides a final opportunity to remove obviously shrivelled and/or damaged kernels before the grinding process; and, potentially, to simultaneously reduce the level of aflatoxin in the final product. The HACCP team was uncertain whether hand-sorting after roasting would have a significant effect on the aflatoxin level and, consequently, did not define step 11 as a CCP. However, this step would become a CCP if subsequent studies clearly demonstrated the efficacy of the hand-sorting process as a means of removing aflatoxin.

Steps 12 & 13: At factory, grinding and packing - GMP

The quality of the grinding and packing procedures is controlled by GMP. The grinding procedure, used in the conversion of kernels to peanut butter, will effect the distribution of aflatoxin in the end-product, but will not change the overall level of contamination.

Stage 11: Establish verification procedures

Verification procedures will be established for each of the CCPs, and the HACCP plan will be regularly audited, and amended as necessary

Stage 12: Establish documentation and record keeping

The HACCP plan will be fully documented, and appropriate records kept at each CCP.

Table 10. HACCP Plan Worksheet: Peanut butter produced in southern Africa