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How do you compare a result from a dried or concentrated product to the legal limit?

You submit a dried herb or a fruit concentrate for analysis. The result comes in. But what actually happened during processing and which limit do you compare it to?

The problem: water disappears, pesticides don't

When a product is dried or concentrated, moisture leaves. Pesticides and contaminants largely stay behind. The result: a higher concentration per kilogram than in the fresh product.

Most legal limits, however, apply to the fresh product. Compare your result directly to that limit, and the comparison breaks down, potentially leading to a false non-compliance.

What does the legislation say?

For pesticides (Regulation 396/2005):

Limits apply to the fresh product in almost all cases, with a few exceptions such as dried beans, tea and spices. If you test a processed product, you're allowed to recalculate the limit using a processing factor.

One important nuance: this doesn't work both ways. If you have an exceedance on a fresh product, you cannot "dilute it away" by processing it. That rule exists to protect good agricultural practices; a processed product can never be used to mask a problem at the source.

For contaminants (Regulation 2023/915):

Here, limits are often set very specifically per product, sometimes for both the fresh and the processed product. 

For ochratoxin A, for example, there's a limit for raw wheat and a separate one for bread. Dried fruit and dried herbs also have their own limits in the contaminants legislation, while no such specific limits exist in the pesticide legislation.

In short: you can't apply one rule to all contaminants. For each substance, you need to check which limit applies and whether a recalculation is relevant or even permitted.

Where do you find the right processing factor?

This is where it gets tricky. A complete, official list of processing factors per substance, product and process doesn't exist and isn't likely to appear anytime soon. The European Commission does provide guidance with three options:

• Substance-specific factors: the most accurate approach, specific to one active substance, one product and one process. The EFSA database contains data for this, but covers only a fraction of all possible combinations.
• Extrapolation: for very similar products (e.g. plum and cherry), you can apply the same factor — still per active substance.
• Generic factors: one factor per process (e.g. drying), applied to all substances. Less precise, but by far the most used approach in practice — and accepted by the competent authorities.

How much factors can differ is illustrated by the example of grapes to raisins: one active substance has a factor of 0.12 (dilution), another 3.4 (strong concentration). Same step in the chain, completely different effect.

How do we handle this?

(New!) For dried and concentrated sample types, you can now provide your processing factor directly via extranet.

• If recalculation is legally permitted, your report will show both the original legal limit and the recalculated value.
• If recalculation is not permitted, for example because the limit already applies to the processed product,  you'll see "not applicable."

One clear report. No need to figure out which rules apply to your product.

Our recommendation

Where possible, test the product to which the legal limit directly applies. A one-to-one comparison is always the most reliable.

If you do need a processing factor: go for a substance-specific one where you can. If that's not practical, we'll apply the correct recalculation based on the generic factor you provide.

Want to know more?

Questions about which limit applies to your product, or how to provide a processing factor? Contact your Primoris account manager or reach us at hello@primoris-lab.com.