Prof. Raymond D. Coker
Founder & Director
Raymond Coker Consulting Limited
SAMPLING, SAMPLE PREPARATION AND MYCOTOXIN ANALYSIS METHODS
It is evident from Figure 2, that effective sampling, sample preparation and mycotoxin analysis methods are required at CCPs throughout the supply chain.
It is essential that any sample collected from a batch of raw material or finished product is truly representative of that batch. If not, all future activities will be largely invalidated.
Examples of a variety of batches of food and feed material, from a truck-load to a 20-30 thousand tonne shipment, are illustrated in Figure 5. The collection of representative samples from a very large shipment presents a particular challenge (Coker et al, 2000).
The main issues associated with accurate sampling are (Coker, 1989, 1998a,)
• The distribution of mycotoxins is highly skewed, especially in whole grains and kernels (e.g. corn and groundnut kernels)
• Only one in a thousand grains or kernels may contain the mycotoxin (especially aflatoxins)
• Sampling plans must accommodate this skewed distribution of mycotoxins
• Consequently, samples of whole grains and kernels are large and composed of a large number (typically one hundred) of ‘incremental’ samples
• However, since the production of mixed feed produces a more homogeneous distribution of mycotoxins, samples of mixed feed are significantly smaller than those of whole grains & kernels
Appropriate sample sizes for whole kernels, required for the determination of aflatoxin concentration (based upon a statistically-determined sample size of 40,000 grains or kernels); and sample sizes for heavily processed (very well mixed) oilseed meals, are as follows:
• groundnuts - 20kg
• maize - 10kg
• wheat - 5kg
• heavily processed oilseed meals - 2kg
Once a representative sample has been collected, it is essential that it is processed – the sample preparation step – in a manner which produces a laboratory sample which is representative of the original sample. In other words, it is essential that the laboratory sample is representative of the batch from which the original sample was taken (Figure 6).
The overhead mixer converts the original representative sample into a homogenous aqueous slurry, from which representative laboratory samples (e.g. 100g) can then be directly analysed for the appropriate mycotoxins.
The mill produces a ground representative sample which must then be converted into a ground, representative subsample by riffle division or coning and quartering. Representative subsamples are typically 1kg in weight.
Finally, the subsampling mill simultaneously converts an original representative sample into a ground, representative subsample.
Before being subjected to mycotoxin analysis, a ground, representative subsample should be converted into a homogeneous aqueous slurry, using a high-speed blender, from which representative laboratory samples can be taken.
This process is illustrated in Figure 7, including examples of the ratio of commodity to water which should be used for homogenisation.
MYCOTOXIN ANALYSIS METHODS
Once a representative laboratory sample has been selected, it is essential that it is analysed using an accurate and precise procedure which, ideally, can simultaneously determine multiple mycotoxins.
The required attributes of an analysis method which can be successfully employed at Critical Control Points within a supply chain are described in Table 4.
Current methods for the analysis of mycotoxins include: high performance liquid chromatography, HPLC (together with ultra-performance liquid chromatography, UPLC; and liquid chromatography-tandem mass spectrometry, LC-MS/MS); enzyme linked immunosorbent assay, ELISA; lateral flow devices, LFD; fluorometric methods; and the recently-developed ToxiMet System.
Methods which are currently used for the analysis of mycotoxins in China have been reviewed by Shi et al (2018)
The ToxiMet System reportedly meets the required attributes of an analysis method which can be successfully employed at Critical Control Points (Table 4). It possesses the accuracy and precision of HPLC procedures, together with the speed and simplicity of ELISA, lateral flow and fluorometric procedures (Figure 8). The ToxiMet System can also simultaneously determine multiple mycotoxins.
Blockchain is a distributed database composed of a network of interconnected computers that are used to keep a distributed ledger of information. It was originally developed as a means of securely and transparently managing transactions involving Bitcoin and other crypto-currencies.
Blockchain may be considered to be a shared public ledger on which all transactions are registered, and serves as a proof of all the transactions performed on the network.
In other words, each computer connected to the network has a copy of the blockchain, thus ensuring the synchronised, real-time transparency, to all participants, of all transactions performed within the network. Each time a digital transaction is performed, it is grouped together in a cryptographically-protected block, with other recent transactions, and is then distributed to the entire network.
Data is immutable once it has been written to a blockchain – it cannot be modified by anyone.
BLOCKCHAIN AND FOOD SUPPLY CHAINS
Given a blockchain’s combined characteristics of transparency and immutability, it has attracted significant interest as a vehicle for the improved management of food supply chains. Blockchain has the potential to give growers, suppliers, processors, distributors, retailers, regulators and consumers immediate access to reliable information on the origin and quality of food.
However, it must be remembered that a blockchain potentially facilitates the vastly improved management of food supply chains by providing a highly effective vehicle for the transparent application of a variety of well-established food safety control measures, including Good Agricultural Practice (GAP), Good Storage Practice (GSP), Good Hygiene Practice (GHP), and Good Manufacturing Practice (GMP) and Hazard Analysis and Critical Control Points (HACCP), in combination with GS1 identification standards. (GS1 standards create a common foundation for businesses, by uniquely identifying, accurately capturing and automatically sharing vital information about products, locations, assets etc).
Importantly, for blockchain technology to be effective, it will always be dependent upon the accuracy of information entered into the system, throughout the supply chain.
Although the application of blockchain technology to the management of food supply chains is still under development, a variety of initiatives are already underway.
For example, Cargill has employed blockchain in a pilot study, which allowed consumers to trace their individual Thanksgiving turkey from the farm where it was raised to the store where it was purchased.
Similarly, IBM has launched the Blockchain Food Safety Alliance, together with Walmart, the Tsinghua University National Engineering Laboratory for E-Commerce Technologies and Chinese e-retailer JD.com (which is both the largest e-commerce company in China and the country's largest retailer by revenue). The alliance will collaborate to enhance food tracking, traceability and safety in China, achieving greater transparency across the food supply chain.
Finally, IBM is collaborating with major global food companies (Dole, Driscoll’s, Golden State Foods, Kroger, McCormick and Company, McLane Company, Nestlé, Tyson Foods, Unilever and Walmart) to identify new areas where the global supply chain can benefit from blockchain technology.
Mycotoxins are destined to remain the silent threat to animal health and productivity, and food safety for the foreseeable future.
Consequently, it is essential that all players in the animal feed and food sectors work in unison to develop and implement procedures that will alleviate the impact of mycotoxins as far as is practicably achievable.
The author acknowledges that this article contains some material previously published in Coker, R. D. (1997) Mycotoxins and their Control: Constraints and Opportunities, NRI Bulletin 73, Chatham; and draws upon material previously published in Manual on the Application of the HACCP System in Mycotoxin Prevention and Control. Volume 73, 2001. FAO, Rome, to which the author was a major contributor.