HPLC-FLD Confirms Aflatoxins in Peanuts, Pistachios

Aflatoxins and ochratoxin A are two harmful toxins that show up in nuts, and they are a major food safety concern because they are toxic and tend to be unevenly spread throughout a batch, some nuts might be contaminated while others right next to them are not. To tackle this problem, researchers from the University of Lleida in Spain and the Hellenic Agricultural Organisation in Greece teamed up to test whether near-infrared hyperspectral imaging (NIR-HSI) could be used as a fast, non-destructive way to sort individual nuts as contaminated or safe. They backed this up with an initial round of testing using high-performance liquid chromatography with a fluorescence detector (HPLC-FLD). A paper based on this research was published in the journal Food Research International.¹

Why Are Aflatoxins and Ochratoxin A Serious Concerns, and Why Is Better Detection Needed?

Aflatoxins and ochratoxin A, toxic byproducts made by the mold species Aspergillus and Penicillium), are a major food safety issue when it comes to peanuts and pistachios.^2,3 These toxins form when mold takes hold under the right conditions, mainly warm, humid environments, and this can happen either while the crop is still growing or after harvest.^4,5Aflatoxins and ochratoxin A are some of the most dangerous toxins found in food, they're known to cause cancer, weaken the immune system, and damage the kidneys.⁶When nuts do not meet these safety limits, it causes financial damage all along the supply chain. Products lose value, testing gets more expensive, access to markets shrinks, farmers earn less, and public health systems end up footing extra costs.⁷ The bigger economic fallout shows up as disrupted trade, shipments getting turned away at borders, and shaky markets, and it hits especially hard in places that rely heavily on exporting their crops.⁸These ongoing problems make it clear that strong, scalable ways to detect and manage these toxins are needed to keep food safe and protect the economics of the industry.⁹

How Prevalent was Toxin Contamination in the Nuts, and How Well Did the Testing Detect It?

In this study, the researchers tested 52 peanut samples and 33 pistachio samples, all store-bought, for the presence of aflatoxins and ochratoxin A using the HPLC-FLD method. They found aflatoxin B1 in about 8% of the peanut samples, and ochratoxin A in about 3% of the pistachio samples. Even in the contaminated samples, the toxin levels were low, well within the legal safety limits set by the EU.¹

Next, the team used near-infrared hyperspectral imaging to sort individual peanuts based on whether they contained aflatoxins (they could not test the pistachios this way since they only had one contaminated sample to work with). They used an artificial neural network, combined with the data-simplifying technique Principal Component Analysis, to classify the nuts. This approach worked well, especially when the data was processed using second-derivative preprocessing. The most useful wavelengths of light for spotting contamination fell between 1100 and 1350 nanometers. One notable strength of this study is that they used real-world, naturally contaminated nuts with low toxin levels, rather than artificially spiking clean nuts with toxins, which makes the results more representative of what occurs in the real world.¹

“Although the limited number of positive samples and their heterogeneous distribution present challenges for sensitivity,” write the authors of the paper,¹ “the findings provided evidence of the potential of NIR-HSI as a rapid, non-destructive tool to complement chromatographic methods. Future validation with larger datasets and integration into industrial sorting systems could contribute to improved routine monitoring and safer nut supply chains.”

Read More on Similar Topics
Chromatography Targets Pesticides in Peanuts

References

1. Nazareth, T.; Marin, S.; Ramos, A. J. et al. Assessment of Near-Infrared Hyperspectral Imaging for the Discrimination of Naturally Aflatoxin-Contaminated Nuts. Food Res Int. 2026, 242 (Pt 2), 119923. DOI: 10.1016/j.foodres.2026.119923
2. Alsalabi, F. A.; Hassan, Z. U.; Al-Thani, R. F. et al. Molecular Identification and Biocontrol of Ochratoxigenic Fungi and Ochratoxin A in Animal Feed Marketed in the State of Qatar. Heliyon2023, 9 (1), e12835. DOI: 10.1016/j.heliyon.2023.e12835
3. Naeem, I.; Ismail, A.; Riaz, M. et al. Aflatoxins in the Rice Production Chain: A Review on Prevalence, Detection, and Decontamination Strategies. Food ResInt. 2024, 188, 114441. DOI: 10.1016/j.foodres.2024.114441
4. Mahato, D. K.; Lee, K. E.; Kamle, M. et al. Aflatoxins in Food and Feed: An Overview on Prevalence, Detection and Control Strategies. Front. Microbiol.2019, 10, 483502. DOI: 10.3389/fmicb.2019.02266
5. Mannani, N.; El Boujamaai, M.; Sifou, A. et al. Aflatoxins and Ochratoxin A in Dried Fruits from Morocco: Monitoring, Regulatory Aspects, and Exposure Assessment. Regul. Toxicol. Pharmacol.2023, 145, 105503. DOI: 10.1016/j.yrtph.2023.105503
6. Rushing, B. R.; Selim. M. I. Aflatoxin B1: A Review on Metabolism, Toxicity, Occurrence in Food, Occupational Exposure, and Detoxification Methods. Food Chem. Toxicol.2019, 124, 81-100. DOI: 10.1016/J.FCT.2018.11.047
7. Meneely, J. P.; Kolawole, O.; Haughey, S. A. et al. The Challenge of Global Aflatoxins Legislation with a Focus on Peanuts and Peanut Products: A Systematic Review. Expo. Health2023, 15 (2), 467-487. DOI: 10.1007/s12403-022-00499-9
8. Shabeer, S.; Asad, S.; Jamal, A. et al. Aflatoxin Contamination, Its Impact and Management Strategies: An Updated Review. Toxins2022, 14 (5), 307. DOI: 10.3390/TOXINS14050307
9. Sipos, P.; Peles, F.; Brassó, D. L. et al. Physical and Chemical Methods for Reduction in Aflatoxin Content of Feed and Food. Toxins2021, 13 (3), 204. DOI: 10.3390/TOXINS13030204