What are aflatoxins in hazelnuts? Formation and control

Aflatoxin control in hazelnuts requires more than a single processing step. Orchard conditions, delays after harvest, drying, storage and lot analysis should be considered together. This first article explains what the risk means. The second covers harvesting and drying; the third explores nitrogen storage and analytical documentation.

Mould and aflatoxins are different things

Aflatoxins are toxins produced by certain strains of Aspergillus flavus and Aspergillus parasiticus. Distinguishing the organism from its chemical products matters: controlling mould growth does not demonstrate that previously formed toxins have disappeared. The World Health Organization explains that mycotoxins can develop before or after harvest and that warm, damp conditions support mould growth. Aflatoxins are important in food safety controls because long-term exposure carries serious health risks. (WHO)

Assessing a lot involves two separate questions: Do its current conditions limit further formation? Does it contain measurable aflatoxins? Process and storage records address the first; appropriate sampling and analysis address the second. This distinction explains why “well stored” cannot substitute for an analytical result.

Assess risk through the product's history

Research conducted in Turkish hazelnut orchards links rain-delayed drying with risk. The same study did not detect aflatoxins in every period with high water activity. A risk condition and actual contamination are therefore different findings; a single environmental observation cannot establish the status of an entire region or product. (Özay and colleagues)

For procurement, this means turning a general description such as “quality hazelnuts” into specific information. Which lot is offered? When were harvesting and drying completed? Is the product in-shell or shelled? How were storage conditions monitored? These questions connect information from different stages. Reading product specifications, traceability and analysis together creates a stronger basis for decisions.

Appearance and roasting do not establish compliance

Visual sorting is a valuable control, but it does not measure aflatoxin concentration. Buyers should not interpret clean appearance as a laboratory result. Similarly, “roasted” describes processing; it does not independently establish compliance.

EFSA explains that heat treatments can sometimes reduce aflatoxins but do not completely remove them. Effects depend on the food and process, so results for another food cannot establish hazelnut performance. Roasting does not replace aflatoxin control. (EFSA)

The same purchasing logic applies to hazelnut flour, roasted nuts and hazelnut spreads: buyers should request ingredient lot information and an appropriate compliance assessment alongside the final product specification. A processing label does not, by itself, answer questions about the ingredient's history.

Read analytical reports alongside product identity

Total aflatoxins comprise B1, B2, G1 and G2; a B1-only result is different. (EFSA assessment)

Matching the analysis to the lot being purchased is an important document check. Date, product form, lot identifier and report scope should be reviewed together. Laboratory competence should also be assessed through the current accreditation scope for the relevant product and analysis. Published information from Ministry laboratories illustrates that analytical scope is considered at product and method level. (Bolu Food Control Laboratory)

Buyers should ask clear questions:

• Does the report's lot identifier match the quotation and shipment?
• Does the report cover B1, total aflatoxins or both?
• Who collected the sample, when and by which procedure?
• How was the result assessed for the intended use and destination market?

A useful supply discussion makes these questions as visible as price and quantity. When discussing hazelnut supply, sharing the required product form, destination market and documentation expectations helps structure the assessment. Continue with our harvesting and drying guide for the practical steps in the field.

Sources

WHO: Mycotoxins, EFSA: Aflatoxin risk assessment, Research on Turkish hazelnuts, Bolu Food Control Laboratory.