LC–MS/MS Tracks Mycotoxins in Stored Nigerian Rice

A multinational team of researchers set out to track how molds and the toxins they produce build up in rice in Nigeria, both during processing after harvest and over 90 days of storage. They compared two approaches: conventional processing and an improved method. To identify the molds, they combined several different identification techniques, and they measured the toxins using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Their goal was to help prevent crop losses and strengthen food security by keeping rice from spoiling after harvest and by controlling these toxins. A paper based on their work was published in the journal Mycotoxin Research.¹

Why Is Mold and Toxin Contamination in Nigerian Rice a Concern?

Like in many other countries in sub-Saharan Africa, most rice in Nigeria is grown by small-scale farmers who raise crops mainly to feed their own families, and rice is grown in almost 85% of the country's states.² Even so, Nigeria doesn't grow enough rice to keep up with growing demand for this everyday food. Despite many efforts to boost local production, the country still must import huge amounts of rice every year to make up the difference.³

Pests pose a major threat to rice at every stage, from the field to people's plates. One of the biggest dangers comes from fungi that produce harmful toxins. These fungi can infect rice while it's still growing, but the bigger risk comes after harvest, when rice is handled and stored in poor conditions.^4,5

The authors point to earlier studies that identified molds in rice, measured the toxins they produce, or did both. However, most of those studies tested rice that had already been processed or stored and was being sold at local markets.¹ Very little is known about how contamination happens during the steps between harvest and sale.^5,6 This gap matters: a recent global review found that half of the white rice sold in African stores was contaminated with fungal toxins. The highest level of aflatoxin found, 1,642 µg/kg, was twice as high as the highest level seen in corn from Asia.⁷

What Molds and Toxins Did the Researchers Find in the Rice, and How Did Processing and Storage Affect Them?

The researchers collected 325 samples of fungi from rice handled through two different processing methods. These fungi belonged to 21 groups, including 10 types of molds, 1 crusty fungus, and 10 types of yeast, and 54 species in all. Rice from the conventional processing method carried a wider variety of fungi than rice from the improved method. A common mold called Aspergillus was the most widespread fungus in both, while yeasts showed up only in the conventionally processed rice. Certain kinds of Aspergillus and Penicillium molds were especially common in stored rice from both methods.¹

When the researchers grew 38 of the mold samples in the lab, they found 106 different chemicals produced by the molds. Some of these were unusual, and some could help identify particular mold species. They also found 15 different fungal toxins in the rice at various points during processing and storage.¹

The two methods affected these toxins differently. Rice that went through the improved process and was stored for 90 days in airtight bags had 9% less aflatoxin, a dangerous toxin, while conventionally processed rice showed no drop. On the other hand, conventionally processed rice stored in jute sacks for 90 days saw at least twice as large a drop in three other toxins (fumonisin, nivalenol, and tenuazonic acid) as rice stored in airtight bags. Levels of another toxin, citrinin, along with its breakdown product, kept rising during storage with both methods.¹

“This study,” wrote the authors of the paper,¹ “highlights the critical control points in the two rice process chains and provides insights into possible mycotoxin control approaches along the chain including in storage.”

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References

1. Oyedele, O. A.; Akinyemi, M. O.; Sulyok, M. et al. Fungi and Mycotoxins During Conventional and Improved Postharvest Processing and Storage of Local Rice in Nigeria. Mycotoxin Res. 2026, 42 (4), 73. DOI: 10.1007/s12550-026-00683-9
2. Ayanlade, A.; Radeny, M. COVID-19 and Food Security in Sub-Saharan Africa: Implications of Lockdown During Agricultural Planting Seasons. NPJ Sci Food 2020, 4, 13. DOI: 10.1038/s41538-020-00073-0
3. Ismaila, U.; Wada, A. C.; Daniya, E. et al. Meeting the Local Rice Needs in Nigeria Through Effective Weed Management. Sust Agric Res. 2013, 2 (2), 37–48. DOI: 10.5539/sar.v2n2p37
4. Makun, H. A.; Dutton, M. F.; Njobeh, P. B. et al. Incidence, Phylogeny and Mycotoxigenic Potentials of Fungi Isolated from Rice in Niger State, Nigeria. J Food Saf. 2011, 31, 334–349. DOI: 10.1111/j.1745-4565.2011.00305.x
5. Tang, E. N.; Ndindeng, S. A.; Bigoga, J. et al. Mycotoxin Concentrations in Rice from Three Climatic Locations in Africa as Affected by Grain Quality, Production Site, and Storage Duration. Food Sci Nutr. 2019, 7 (4), 1274-1287. DOI: 10.1002/fsn3.959
6. Monteiro, C. S.; Pinto, E.; López-Ruiz, R. et al. Integrated Assessment of Fungi Contamination and Mycotoxins Levels Across the Rice Processing Chain. Toxins (Basel) 2025, 17 (9), 468. DOI: 10.3390/toxins17090468
7. Lee, H. J.; Ryu, D. Worldwide Occurrence of Mycotoxins in Cereals and Cereal-Derived Food Products: Public Health Perspectives of Their Co-occurrence. J Agric Food Chem. 2017, 65 (33), 7034-7051. DOI: 10.1021/acs.jafc.6b04847