From the Ground to the Processor: Finding Where Aflatoxin Appears
Scientists know some of the factors that seem to encourage Aspergillus mold to grow, produce aflatoxin and ruin the peanut crop. Whether the plants struggled through drought, whether the harvest was dried on the ground or whether the nuts were stored in porous sacks all seem to influence whether aflatoxin appears.
Much of the research into those areas is isolated, however, and looks at only one or two steps in the production process rather than putting various factors together in different scenarios to see what combination of interventions works best to produce a crop free of aflatoxin.
“My main work is to assess agricultural practices and interventions on mitigating aflatoxins in the value chain,” says William Appaw, a master’s student in Food Science and Technology at Kwame Nkrumah University of Science and Technology (KNUST) in Ghana. “I’m not looking just at the individual steps in the value chain but trying to look at it more holistically, like a puzzle.”
Appaw presented his preliminary findings in January 2016 at the West Africa MSN-GLEE (Multi-Sectoral Nutrition Strategy Global Learning & Evidence Exchange) workshop in Accra, Ghana.
Working with Dr. David Jordan, one of the lead researchers for Feed the Future’s Peanut & Mycotoxin Innovation Lab, Prof. William Otto Ellis at KNUST and Dr. Moses Mochiah at the Crops Research Institute, Appaw is tracking the aflatoxin (if any) in crops grown, dried and stored under certain conditions. The Ghana Peanut Value Chain Interventions project looks to quantify the effectiveness of some interventions—such as drying groundnuts on tarps or storing them in hermetic bags—to see what works best.
Appaw presented his preliminary findings in January 2016 at the West Africa Multi-sectoral Nutrition Strategy Global Learning & Evidence Exchange (MSN-GLEE) workshop in Accra, Ghana. Sponsored by USAID’s Strengthening Partnerships in Nutrition Globally (SPRING), the Bureau for Food Security and the Bureau for Global Health, the workshop brought together USAID Missions in West Africa, implementing partners and host country governments to share research in nearly two dozen areas.
Appaw became interested in food safety at a young age. As his mother was a baker, he grew up helping to procure ingredients for baking and food preparation.
“People who are investigating aflatoxins or mycotoxins over the years work as individual/single units with little or no links between these units or stakeholders. When you have that, there isn’t good coordination, so you don’t get the complete picture of the problem being solved. But when one works using this holistic, multi-disciplinary approach in aflatoxin mitigating, it gives a better idea which parts of the interventions work and where we need to focus more effort in the value chain,” Appaw said.
Working with farmers in two villages, the researchers tracked field production, drying and storage techniques, taking samples at each stage for testing at KNUST. For example, some farmers used only one weeding, while others did two weedings. Researchers dried some of the peanuts on the ground and others on a tarp. And from the overall group of farms, some stored the dried nuts in a hermetic bag on a pallet and some in a Polysack on a cement floor.
The method gave researchers several scenarios and various testing points to see if and where aflatoxin showed up in the crop via the value chain.
While researchers dried and stored samples during the plenary stage of the research, farmers will do the drying and storage this year to give an even more realistic assessment of the value of the interventions on the farm.
“Most of the farmers have never used a tarpaulin or (hermetic) sack before, so we are providing them one,” Appaw said. “Some growers weren’t aware that drying a crop on a tarp reduces the incidence of mold and aflatoxin. Others knew it might be an alternative but associate the method more with other crops, such as cocoa. Still others knew a tarp contribute to a cleaner groundnut crop but didn’t realize how drastic the difference can be”.
“When you have farmers be part of the research work, they own the research and appreciate the result or outcomes,” Appaw says. “When the research is done, we aren’t just trying to impart something abstract but rather a practical knowledge to them. They have used it. They know it works and can easily adopt the technology.”
Appaw was surprised at the difference some of the interventions provided.
At the harvesting stage, researchers couldn’t see a difference in the aflatoxin levels of groundnuts grown under different field practices. But after those nuts were dried—whether using the traditional method or a tarp—the groundnuts that were grown under more rigorous weeding and other care showed less aflatoxin.
Overall, however, the groundnuts dried on a tarp did far better than those dried on the ground, with 85 percent less aflatoxin.
Groundnuts dried on a tarp seem to develop less aflatoxin than than those dried on the ground.
Crop stored for nine months in a hermetic bag also showed significantly less aflatoxin than groundnuts stored in woven Polysacks.
Using all the interventions, the researchers found up to 99 percent less aflatoxin than in groundnuts grown, dried and stored in traditional ways.
Perhaps the most dramatic impact came from storing in hermetic bags. Denied moisture and air, mold couldn’t grow and therefore couldn’t produce aflatoxin. Results showed a range from no increase in aflatoxin up to 15 percent increase when groundnuts were stored for months in the hermetic bag.
Storing groundnut in hermetic bags greatly reduced the amount of aflatoxin appearing in nuts.
“For us, that is very important, because most farmers keep some of their seeds and plant them the following season. Some even keep them to sell through the lean season,” Appaw said. “This could mean more profit for those nuts that are stored or, eventually, an opportunity to feed the local industry and also export because they have had consistently low aflatoxin readings.”
Appaw became interested in food safety at a young age as his mother was a baker, so he grew up helping to procure ingredients for bakery and food preparation. His mentors Professors Ellis and Oduro have also been influential and supportive in his interest in the area.
“I want farmers to have these simple technologies and know they can use them to increase their yield, incomes and turnovers which will improve their overall livelihood,” he said. “We also want to be more confident that the groundnuts we consume are safe and within acceptable limits for aflatoxin”.
“But most of all, I want the kids to have good, healthy, nutritious peanuts and peanut products to eat, which will improve their growth and mental development. The ultimate goal is to help achieve the SDGs (Sustainable Development Goals) of no poverty, zero hunger and good health and wellbeing.”
Following completion of his master’s degree at KNUST, Appaw hopes to continue on to complete a doctorate.
This post was written by Allison Floyd of the Peanut & Mycotoxin Innovation Lab at the University of Georgia