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From Clean Cocoa to Healthy Fish: Cameroonian Researchers Focus on Food Safety

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 HYDRAC, a company specializing in the use of nuclear techniques for industry, has become the first analytical laboratory in Cameroon to receive accreditation in food safety using nuclear techniques. (Photo: M. Gaspar / IAEA)

DOUALA and YAOUNDE, CAMEROON – Cocoa production represents over 8 per cent of Cameroon’s agricultural output, but exports have been wobbly as a result of a lack of quality control tests available locally.

“Without quality assurance and microbiological testing, the sales price is bad – and the income for producers is meagre, resulting in persistent poverty,” said Elie Bertrand Mutngi, Director of Quality and Sustainability at Cameroon’s National Cocoa and Coffee Board.  

This is now expected to change, as a local company with a long history of using nuclear techniques for testing in the oil and gas sector, has begun to offer tests for chemical residues and contaminants in cocoa and coffee. The certification they provide, which exporters could obtain only from European labs before, is a prerequisite for export to most countries.

HYDRAC, the Douala-based majority state-owned company, has used nuclear techniques for non-destructive testing of pipes, construction material as well as hydrocarbons. It has cooperated with the IAEA since 1995, when the need for such tests first emerged during the construction of an oil pipeline connecting landlocked Chad with the Cameroonian coast.

Food security is a key pillar of the government’s 2020-2030 National Development Strategy, and it requires food safety systems in place. Furthermore, safety and high-quality of food are also paramount in order for the country to increase its exports. It is in support of this plan that HYDRAC has decided to diversify into food testing, said David Ekoume, the company’s Director General. Products such as cocoa and coffee sometimes contain pesticide residues and other toxins above safety limits established by the European Union and other import markets.

The IAEA, through its technical cooperation programme and in partnership with the Food and Agriculture Organization of the United Nations, has helped train seven analytical chemists and managers in the use of nuclear and nuclear-based analytical techniques in food safety and has supported the lab with equipment including an atomic absorption spectrometer, a gas chromatograph coupled with a mass spectrometer as well as radio receptor assay tool kits to perform relevant tests (see The Science box).

“Previously a lot of the country’s cocoa and coffee exports were rejected by importers or could only be sold locally at lower prices, due to lack of testing,” Ekoume said. “This is true also for other agricultural exports such as banana and pineapples. We are therefore working to get accreditation as a general food safety lab.”

As of this year, the lab is able to check for mycotoxins, pesticide residues, toxic metals, polycyclic aromatic hydrocarbons (PAHs), which occur naturally in oil and can contaminate food, and polychlorinated biphenyls (PCBs), a highly carcinogenic substance formerly used in industrial and consumer products. The extension of ISO accreditation for HYDRAC’s lab from cocoa and coffee to food in general is under way and should be completed this year, in August 2022, Ekouma said.

A good catch: studying contamination in aquaculture

Fish is a key part of the Cameroonian diet. Researchers using nuclear related techniques are working to improve food safety by identifying contaminants in fish raised in aquaculture. (Photo: M. Gaspar / IAEA)

Increasing domestic fish production is another important pillar of the government’s food security strategy. Currently, the country imports 230,000 tons of fish each year, and various government programmes support the development of aquaculture to reduce import dependence.

But there is a catch: often the ponds used for aquaculture are contaminated by manure, veterinary drug residues and other agricultural byproducts that are washed into the ponds on integrated farms, which raise animals such as pigs and poultry. There is currently no legislation in place to control these substances, and researchers at the Centre for Food and Nutrition Research (IMPM) are working on providing data to develop one, with the support of IAEA and FAO.

“Inadequate sanitation and control systems can lead to serious environmental, economic and health problems,” said Judith Tsafack, Deputy Head. “The intensification of aquaculture requires the monitoring of the impact of farmer’s practices on the environment and the farmed product.”

With support from the IAEA and FAO, IMPM has used radio receptor assay to assess the presence of different antimicrobial residues and other contaminants in fish and environmental samples.

A series of preliminary pilot studies by Tsafack and her colleagues, published in various peer-reviewed journals, has found that fish ponds are sources of pathogenic bacteria and fungi, as well as of antimicrobial residues. Between 10% and 30% of the samples studied showed non-compliance had concentrations of one or more toxins above safety limits.

“This study is a clear example of how nuclear research can provide information for policymakers and form the basis of relevant legislation,” said Rebecca Madelaine Ebelle Etame, Secretary General at Cameroon’s Ministry of Scientific Research and Innovation.

THE SCIENCE

Residue/contaminant testing in food using nuclear-based techniques

Specialists at HYDRAC and IMPM use various nuclear and isotopic techniques for testing for food contaminants and residues from pesticides. Here is how these techniques work:

Radio receptor assay: these are easy-to-perform and accurate tests that can detect various antimicrobials, mycotoxins and pesticides. In this test, binding agents, such as bacteria that selectively bind the residues or contaminants, are added to the sample, along with a version of the contaminant marked with a radioactive tracer, typically tritium (3H) or carbon-14 (14C). If the sample is contaminated, the contaminant in the food sample competes with the marked contaminant, so less of the latter is bound. If the sample does not contain the target drug residues or other contaminant, the agent binds exclusively with the tracer-marked additive. This difference can be measured and the amount of contaminant, if any, determined.

Gas chromatography with mass spectrometry: this analytical “fingerprinting” technique is used to detect and identify very low concentrations of chemicals, in this case contaminants or residues, and distinguish them from other materials. Gas chromatography (GC) is used to separate each component in a mixture before detection by the mass spectrometer and quantification. The different components of the mixture react differently with the material in the chromatographic instrument, which provides the basis for their distinction. The mass spectrometer identifies the chemicals separated by the chromatography based on their molecular masses. The two techniques combined provide a powerful detection and quantification tool and the addition of stable isotope-labelled reference material further improves the sensitivity, accuracy and reliability of the technique.

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