Prof. Raymond D Coker
Founder & Director
Raymond Coker Consulting Limited
THE CONTROL OF MYCOTOXINS
Regulations which stipulate the maximum allowable levels of mycotoxins in foods and feeds have been introduced throughout the globe.
• USA – FDA action levels (FDA, 2000)
• Europe – Legislation for food (EU, 2010)
• Europe – Legislation for animal feed (EU, 2003)
• Rest of World – individual countries have their own regulations
• Codex Alimentarius – Global guidelines for acceptable mycotoxin levels
• Global Food Safety Initiative – stakeholders representing the global food industry collaborate on advancing food safety, by creating a common understanding of what constitutes a good food safety system (farm to fork)
EU regulations governing the levels of mycotoxins in human foods are especially stringent (Regulation (EC) 1881/2006), setting maximum acceptable levels for mycotoxins, and other contaminants.
The regulations include the maximum acceptable levels of the aflatoxins, aflatoxin M1 in milk (resulting from the metabolism of aflatoxin B1 present in dairy feed), ochratoxin A, deoxynivalenol, T-2 toxin, zearalenone and fumonisin B1.
The maximum acceptable level of aflatoxin B1, for example, in foods for direct human consumption, ranges from 0.1 µg/kg in processed cereal-based foods and baby foods for infants and young children, through 2.0 µg/kg in groundnuts, selected tree nuts and dried fruit, and selected cereals, to 8.0 µg/kg in almonds, pistachios and apricot kernels.
The acceptable levels, and guidance levels, of mycotoxins in feed are shown in Table 3.
Hazard Analysis and Critical Control Points (HACCP)
HACCP was originally developed as a microbiological safety system in the early days of the US manned space programme in order to guarantee the safety of astronauts’ food. Up until that time most food safety systems were based on end product testing and could not fully assure safe products as one hundred per cent testing was impossible. A pro-active, process-focused system was needed and the HACCP concept was born. (FAO/IAEA Training and Reference Centre for Food and Pesticide Control, 2001)
HACCP is a system that identifies, evaluates and controls hazards which are significant for food and feed safety. It is a structured, systematic approach for the control of food and feed safety throughout the commodity supply chain (Figure 2), from the field to the fork.
HACCP builds on the foundations of well-established quality management systems such as Good Agricultural Practice (GAP), Good Storage Practice (GSP), Good Hygiene Practice (GHP) and Good Manufacturing Practice (GMP).
HACCP focuses upon the pro-active control of the process, as opposed to relying entirely on end-product testing.
Briefly, the main steps in the implementation of a HACCP Plan may be described as:
1. Identify the hazard (mycotoxins)
2. Locate those points where it is essential that the hazard is controlled (Critical Control Points, CCPs)
3. Identify appropriate Control Measures at the CCPs
A HACCP Plan for the Production of Maize-based Animal Feed in South East Asia
This HACCP plan considers the utilisation of the yellow maize kernels in a feed mill in Southeast Asia. The mill usually offered contracts to Secondary Traders for the supply of maize of a specified quality, but would also buy from visiting traders, especially when stocks were low.
The HACCP Flow Diagram is shown in Figure 3, below.
Only Steps 1 and 5 are CCPs:
Step 1: Procurement and storage, CCP1
It is essential to either purchase maize that has reliable mycotoxin certification, or to segregate acceptable from unacceptable batches on procurement. This control measure will prevent unacceptable levels of mycotoxin entering the feed mill.
The critical limit will be 50 µg/kg aflatoxin B1 in this example, but critical limits for other mycotoxins can also be set if required. The critical limit is monitored by collecting representative samples, ideally in the form of a pre-loading sample collected from the suppliers warehouse. Failing this, representative samples taken from individual trucks, or groups of trucks can be collected for testing. The samples are then analysed on-site by a simple, rapid method, and only those batches containing an acceptable level of mycotoxin are accepted.
It is also very important to procure feed ingredients which have a moisture content at or below the ‘safe’ level corresponding to an water activity (aw) of 0.70.This control measure will prevent aflatoxin, and other mycotoxins, being produced within the feed mill.
The critical limit for maize is an average moisture content of 14%, but it is most important that no bags should contain >15% moisture.
Good Storage Practice (GSP) will include storage on pallets, a clean store, a “first in first out” procedure, and insect and rodent control.
Step 5: Pelleting of feed, CCP2
Moisture is added to feed in the form of dry steam during the pelleting process. Consequently, it is essential that the pellets are cooled to ambient temperature using sufficient aeration, to ensure that the product is dried to a ‘safe’ moisture content.
A critical limit of moisture content is set at 13% for pellets just prior to packaging. This critical limit is monitored by the collection of a representative sample from each batch. The moisture content of each of these samples is then measured using an appropriate, calibrated moisture meter.
The addition of dry steam at 110°C during pelleting will sterilise the feed. Mould spores present in the feed will be killed and this will reduce the likelihood of any subsequent mould contamination.
Although prevention is, of course, always better than cure, examples of curative control measures which can be applied at CCPs, to eliminate a food safety hazard or reduce it to an acceptable level, are described in Figure 4.
The segregation of “good” batches (those that satisfy the regulated maximum acceptable levels of mycotoxin(s)) and “bad” batches (those that contain greater than the maximum acceptable levels) is performed by sampling and analysing the samples collected from individual batches.
Good and bad material can also be segregated by the employment of optical sorting equipment. Here, the characteristics of individual kernels or grain are automatically optically examined (e.g. for evidence of physical &/or mould damage, discolouration, shrivelling etc.)
Chemical detoxification of aflatoxin-contaminated feed, using ammonia under elevated temperature and pressure, has been commercially exploited in, for example, the USA and France (Park & Price, 2001). A small commercial ammonia detoxification plant, employed for the detoxification of poultry and duck feed in India, in shown in Figure 4.
The prevention of the adsorption of mycotoxins from feeds, post ingestion, has been performed by the addition of a variety of adsorbents to animal feed (including Bentonite, activated charcoal and Fuller’s Earth). (Mgbeahuruike et al, 2018). A variety of commercially-produced adsorbents are available.
A variety of other detoxification techniques are currently in the research stage including, the use of bacterial and enzymatic agents, neutral electrolyzed water (to prevent aﬂatoxicosis in Turkey poults) and the use of cold atmospheric pressure plasma (Hassan & Zhu, 2018).