PART III PROCESS SAFETY
6. Case Studies
5.1. Process standards vs. product standards
It is particularly apparent that differences in tolerance levels are potential sources of conflict between countries. The use of good agricultural practices (GAPs) at preharvest and good manufacturing practices (GMPs) at processing and distribu- tion can be used to minimise risk, and provide procedures for reducing mycotox- ins levels acceptable to more countries (CAST, 2003). They compliment product standards and potentially reduce overall economic losses. The Codex recom- mended that GAPs and GMPs be used to establish HACCP safety systems throughout the food production chain (CAST, 2003). HACCP principles are likely to be among the most effective means of lowering risks and economic losses since prevention is more practical than decontamination (at least theoretically).
Mycotoxins are economically important although not publicly prominent.
Balancing economic cost and health benefits has become a source of friction especially for export-reliant developing countries. Trade disputes are likely to persist with respect to regulatory standards. Many factors that influence contam- ination are difficult or impossible to control. Tolerable health risks appear to depend on level of economic development and susceptibility of a nation’s crops.
Mycotoxins standards can be set without internationally accepted risk assess- ments because of the “precautionary principle”. To minimise risk, stakeholders should consider implementing GAPs, GMPs and HACCP principles, although developing countries will require assistance with implementation (CAST, 2003).
milling, baking and extrusion processing. Results demonstrate how processes such as surface scouring of the whole-wheat grain can reduce concentration.
Wheat was inoculated with P. verrusosum and grown to yield 5 µg kg−1 as an experimental sample. Samples were taken at each relevant stage and analysed by HPLC. One batch was untreated, another was scoured to reduce weight by approximately 1%, and another was reduced by 2% by removing the outer coat.
The result was a significant reduction in the level of OTA. A reduction of 65% in bread from white flour was achieved. However, this needs to balance by the eco- nomic loss involved and changes in the characteristics of the flour so processed.
In wholemeal flour more OTA is present in the bran and offal fractions, which are not removed, and so the bread usually contains higher levels of OTA. This was not an industrial scale experiment and any wider implications of the process require careful economic assessments and as to whether it is practical in large scale (Skudamore and Banks, 2004).
However, HACCP is generally regarded as optimal for controlling mycotoxins as for other food safety problems. The following procedures are similar to those that would be implemented for other commodity and mycotoxin systems.
6.2. Copra cake and meal––southeast Asia
Dried coconut flesh (copra) is extracted to produce coconut oil. The residue is called copra cake or copra meal, which is used as protein sources in animal feeds.
The European Union imposed aflatoxin B1regulations on dairy feed of 5 µg kg−1 and copra by-product to 20µg kg−1. Many oil mills would have become non- viable because of these, which would have caused great hardship to millions of coconut farmers. To save the European market, an HACCP approach was used to raise confidence in the product.
An HACCP team was established consisting of an HACCP specialist, oilseeds specialist, socio-economist, mycotoxicologist, mycologist, and drying engineer.
Representatives of the coconut oil industry from the public and private sectors were included.
Aflatoxin was found to be produced within 10 days of splitting coconuts (aw>0.82) when aflatoxin-producing fungi grew. Premature splitting, during har- vest or de-husking, resulted in contamination prior to drying.
Uniform drying within 48 hours of splitting the nut was found to be key to con- trol the aflatoxins. Also, smoke drying was correlated with low-aflatoxin copra.
Sun-dried copra had very high concentrations, and was discouraged. Premiums to farmers were increased to encourage them to produce dry copra. The HACCP steps are provided in Table 9 (see also Coker, 1999).
6.3. Apple juice––South America
Apple juice in South America was at risk of exceeding a 50 µg kg−1target level.
An HACCP team was formed to address this issue involving equivalent special- ists to the copra example above. A product description and the intended use were
verified. As a result of these, a Commodity Flow Diagram (CFD) was prepared and verified by visits to orchards and processing plants.
For the identification of control measures the steps in the CFD where patulin contamination was most likely to occur were identified. Each step was considered in turn. Patulin contamination was likely to be produced in the orchard during growing and bulk storage. There was little risk of further contamination during transportation but damage to apples at this stage can increase the risk of subse- quent contamination. In the factory, patulin contamination is most likely to increase during storage. There was likely to be patulin contamination present in the apples, or the resultant apple juice, at every step in the commodity chain.
Hence it was important to minimise contamination, and reduce levels of contam- ination to the acceptable level.
TABLE9. HACCP Strategy for reducing aflatoxin in coconuts HACCP steps
Step 1: Harvesting and dehusking – Critical Control Point (CCP) 1. Eliminate split nuts to isolate any aflatoxin already present by the use of trained harvesters or de-huskers. Validate by determining the aflatoxin concentration of batches of accepted nuts
Step 2: Splitting nuts – GAP. It is Good Agricultural Practice (GAP) to ensure that the coconut meat is protected from contact with soil, which is a rich source of inoculum
Step 3: Drying – CCP2. Dry to a safe moisture content within 48 hours to prevent growth of fungi and production of aflatoxin. The CCP can be validated by measuring the moisture content of the product
Step 4: Primary trader, procurement and drying -GMP/GSP. It is GMP for primary traders to purchase Grade 1 copra with <1% yellow-green fungus (characteristic of A. flavus or A. parasiticus) and meeting a 12% moisture limit and separating from lower grade. Good storage practice ensured that the copra remained dry
Step 5: Secondary traders, procurement and storage -GMP/GSP. It is also GMP to procure Grade 1 copra, separate from other grades and marketed as low-aflatoxin copra. GSP 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
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 is impor- tant to have adequate aeration because ‘hot spots’ can develop and even result in spontaneous combustion
Step 7: Oil mill, expelling/extracting/pelleting -CCP3. Control measures are unnecessary during expelling of oil and solvent extraction. The high temperatures present will sterilise the copra meal.
The pelleting process was classified as a CCP with a critical limit of 12% moisture in the cooled pellets. This CCP can be validated by determining the moisture content of cooled pellets. An example of GSP of pelleted copra by-product is by placing in bags or in bulk until shipment is possible
Step 8: Shipment -GMP/GSP. If copra by-product is loaded at a moisture content of 12% no increase in aflatoxin contamination is likely during shipping. Sea-water damage must be avoided. Validation procedures provided by the fully quantitative aflatoxin results on the pre-loading samples, taken immediately prior to export. The HACCP Plan will be fully documented, including appropriate records at the farmer and primary trader steps
TABLE10. HACCP procedures for reducing patulin in apple juice HACCP steps
Step 1: Growing in the orchard – GAP. Growth of the mould P. expansum, and subsequent patulin contamination, can occur pre-harvest, where it is associated with damaged and over-ripe fruit. GAP will minimise insect and bird damage
Step 2: At harvest -CCP1. The control measure at this step is to reject rotten and damaged apples during harvesting. Application of this control measure at Step 2 is considered a CCP because it will reduce mould contamination to an acceptable level. The critical limit for this CCP will relate to the percentage of visibly mouldy apples remaining after sorting
Step 3: Farm, bulk storage – GAP. Application of GAP and GSP is necessary to minimise rotting of fruit and subsequent patulin production during bulk storage. Storage of sound apples is important and the length of storage should be minimised, unless refrigerated storage facilities are used
Step 4: Transportation – GAP. There is little risk of patulin contamination during short duration journeys, but any physical damage sustained during transportation, including loading and unloading, will predispose the fruit to subsequent mould attack and possible patulin contami- nation. The correct handling of fruit is therefore required. For long journeys low temperatures are required
Step 5: Factory procurement – GMP. Procurement of batches of low-grade apples, with a high percentage of damaged and rotten fruit, are to be avoided
Step 6: Factory sorting -CCP2. The control measure is sorting to remove visibly mouldy apples. The critical limit for this CCP will be the acceptable percentage of mouldy apples remaining after the sorting procedure, and monitoring will be by use of a trained supervisor
Step 7: Factory, washing -CCP3. The control measure is washing the apples using high-pressure water spraying to remove rotten apple flesh, and patulin, from the fruit. Patulin levels will be reduced at this step, but spores will be suspended in the water. This inoculum will increase the risk of mould growth during bulk storage
Step 8: Bulk storage of whole apples -CCP4. The control measure is to prevent mould growth and patulin production by storing at reduced temperature. If refrigerated storage is not available, then storage time must be minimised. These critical limits for temperature are monitored
Step 9: Pressing/extraction process – GMP. Good Manufacturing Practice will ensure that the presses are cleaned regularly to prevent a build-up of mouldy apple waste which could be a source of patulin contamination
Step 10: Filtration -CCP5. The control measure is the removal of fine, patulin-rich particles held in suspension in the crude juice. Critical limits are set for the size and quantity of particles remaining in the apple juice after filtration. These critical limits are monitored by microscopic examination of samples of apple juice
Step 11: Pasteurisation – CCP. This step is a CCP for the control of bacterial hazards. However, it can also be considered as a CCP for control of the patulin hazard since pasteurisation will destroy spores of P. expansum (although other thermotolerant species are needed to be considered) Step 12: Asceptic packaging process – GMP. Following pasteurisation, it is important to prevent the
re-introduction of microorganisms, including mould spores, during packaging. These procedures are covered by GMP. Packaging is selected which will protect the juice from contamination by micro-organisms, e.g. tetra packs, or glass bottles with air-tight seals for the lid
Step 13: Storage and dispatch – GMP. No subsequent contamination with patulin is likely
N.B. It is noted that analysis for patulin is not recommended which is to the detriment of the HACCP protocol. The current authors recommend that validation analyses are required immediately after step 2. Similarly, fully quantitative analyses are required after step 11. A gene probe is available which may be useful in HACCP protocol development (Paterson, 2006)
6.3.1. Possible patulin control measures
Contamination of the juice could be prevented at stages where rotten or rotting apples could have been rejected from the process, either in the orchard when the fruit is harvested, or during sorting in the factory (FAO, 2003). Post-harvest pat- ulin contamination could have been eliminated, or significantly reduced, by stor- age at <10 ˚C and by minimising storage times. Washing, and in particularly pressure spraying, was shown to be effective in removing patulin from apples.
Patulin can also be removed from apple juice by filtration, when the patulin bound to solid particles of apple flesh is removed. Inactivation of P. expansum spores during pasteurisation at Step 11 reduced the risk of patulin production in the finished juice. A spreadsheet summarising the HACCP plan for patulin in apple juice was developed. The HACCP steps are provided in Table 10.
The HACCP plan was to be audited quarterly, and amended as necessary. Also, it was to be fully documented and appropriate records kept at each CCP.
However, no assessment was performed to estimate whether the mycotoxin was lower after these procedures were implemented. It is assumed that they were largely to build confidence in the industries. It appears likely they would have cre- ated products with generally lower patulin levels. There is no information as to whether the products fulfilled the ultimate purpose of the HACCP analysis, that of the apple juice having consistently lower patulin concentrations.