For the European market, specify non-irradiated and use saturated steam where a reduction is genuinely needed. Irradiation is lawful for this category and it damages aroma less than steam does, but it carries a mandatory declaration that most EU retail programmes will not accept, it is incompatible with organic production, and the alternative is established and widely available. Irradiation earns its place where the product goes to a market that accepts it, where the aroma penalty of steam is commercially unacceptable, or where the supply chain has no other route.
The prior question is more important than the comparison: does the product need a reduction step at all? A spice going into a product with a downstream cook step frequently does not, and buyers routinely pay for a treatment their application never required.
Start with whether you need it
Untreated dried herbs and spices carry a field microbiological load. Total plate counts in the millions per gram are normal on leaf material, and spore-forming organisms survive the drying process. Whether that matters depends entirely on what happens next.
No treatment is usually needed where the spice enters a product that receives a validated thermal process afterwards – a cooked sauce, a retorted meal, a baked good – and where the counts are within your own specification limits for the intake material.
Treatment is usually needed where the spice goes into a ready-to-eat product with no subsequent kill step: a seasoning applied to a finished snack, a dry rub, a table blend, a supplement capsule, a garnish. Here the spice is the last unprocessed ingredient in the chain.
Either way, Regulation (EC) No 2073/2005 sets the food safety criteria that bind, and anything below that line is a buyer specification level rather than a legal limit. Deciding which of the two you are dealing with is the first step in writing the clause.
The comparison
| Criterion | Irradiation | Saturated steam |
|---|---|---|
| EU legal basis | Directive 1999/2/EC framework; Directive 1999/3/EC positive list, one category only, 10 kGy overall average maximum | No specific authorisation regime; a process step under general food hygiene law |
| Products covered | Dried aromatic herbs, spices and vegetable seasonings across the Union, plus national authorisations for other foods in some Member States | Any dried herb or spice |
| Label declaration | Mandatory: “irradiated” or “treated with ionising radiation”, including in ingredient lists | None |
| Volatile oil impact | Lower | Higher, and species-dependent |
| Colour impact | Small at typical doses | Noticeable on green leaf material |
| Moisture impact | None | Adds moisture that has to be removed by re-drying |
| Effect on spores | Effective at the higher end of the permitted dose range | Effective, and the mainstream route for spore reduction in the EU |
| Effect on mycotoxins | None; aflatoxins and ochratoxin A are not destroyed | None |
| Organic compatibility | Not permitted | Permitted |
| EU retail acceptance | Frequently excluded by private specification | Standard practice |
| Facility requirement | Approved and listed irradiation facility; Union approval required for imports | A processing step at the spice plant or a toll processor |
| Verification | Detectable by standardised analytical methods | Process records and microbiological result |
Two rows carry the decision for most European buyers. The label declaration row makes irradiation a marketing decision as well as a technical one, and the organic compatibility row removes it entirely from any organic programme.
When to choose irradiation
Choose it when the destination market accepts it and the aroma penalty of steam is commercially material. High-value aromatic species where the volatile oil is the product, going to a market where the declaration is normal, is the clearest case. The retention advantage over a thermal process is real and measurable.
Choose it when the product form makes steam impractical. Steam adds moisture that has to be removed again, and for some product forms and some plant configurations that re-drying step is either unavailable or does more damage than the treatment saved.
Choose it when the alternative is no treatment at all. A supply chain with no access to steam capacity and a product that genuinely needs a reduction is better served by a lawful, declared, dose-controlled treatment than by shipping an untreated product into a ready-to-eat application.
Choose it when the buyer has explicitly accepted it in writing. This is not a technical criterion but it is the operative one: the treatment is lawful for this category, so the constraint is the customer’s specification rather than the law. Get the acceptance before the shipment, not after.
When to choose non-irradiated with steam treatment
Choose steam when you supply EU retail. Private specifications from major European retail groups routinely exclude irradiated ingredients, and the exclusion usually reaches into compound products through the ingredient declaration requirement. A supplier who treats will find the material rejected at the specification stage rather than at the border.
Choose steam for any organic programme. The EU organic regulation does not permit irradiation, so this is not a preference. An organic certificate and an irradiated ingredient are mutually exclusive.
Choose steam when you want to avoid a consumer-facing declaration. The wording required by Directive 1999/2/EC appears in the ingredient list of the finished product, and for a consumer brand that is a positioning decision taken by marketing rather than by quality.
Choose steam when the aroma loss is acceptable for the application. In a cooked sauce, a soup base or a meat preparation, the volatile oil difference between a steam-treated and an irradiated spice is small relative to what the cooking process removes. The premium on aroma retention is only worth paying where the aroma survives to the plate.
Choose steam when you value process transparency at audit. Steam treatment is a documented process step at a food plant with time, temperature and pressure records that an auditor reads in the same way as any other thermal process. That familiarity has real value in a supplier approval conversation.
What changes in your process
Specification wording. A non-irradiation clause is a positive statement – “not treated with ionising radiation” – supported by a supplier declaration, not an absence of information. If you accept treatment, name the maximum dose and require the facility approval reference.
Moisture control after steam. The re-drying step is where steam treatment goes wrong. A lot that leaves the steriliser correctly treated and arrives above the moisture specification has had a bad re-dry, and the consequence is a water activity problem rather than a microbiological one. Require moisture and water activity on the post-treatment certificate.
Volatile oil retesting. Both treatments move the volatile oil figure. If your specification carries a minimum, it has to be measured after treatment, by hydrodistillation to ISO 6571 on a dry basis, not on the untreated material.
Labelling data flow. Where treated material is used, the declaration has to reach your labelling team. That means it belongs in the raw material master data, not only on the incoming certificate.
Supplier approval. For imported treated material, Union approval of the irradiation facility is a condition of import and is verifiable. Add the check to the approval file rather than discovering the gap at a border control post.
What the table does not show
Neither treatment fixes mycotoxins. Aflatoxins and ochratoxin A are chemically stable and survive both processes. The maximum levels in Commission Regulation (EU) 2023/915 apply regardless, and the controls that matter are agronomic, drying-related and based on sorting and testing. Treating a lot with a mycotoxin problem produces a sterile lot with a mycotoxin problem. Aflatoxin risk in spices covers where the exposure sits.
Neither treatment is a substitute for hygiene. Directive 1999/2/EC states this explicitly for irradiation, and it is equally true of steam. A supplier using treatment to rescue material that should not have reached that point is a supplier with an upstream problem, and the audit question to ask is what the untreated load looks like.
Ethylene oxide is not an option. Fumigation with ethylene oxide is not authorised for food in the Union, and residues in spices and seeds have driven substantial recalls and border enforcement. It is mentioned here only so that it is explicitly excluded at supplier approval.
Dose is not a single number. Directive 1999/3/EC sets a maximum overall average absorbed dose of 10 kGy for the authorised category. Actual doses used vary with the microbiological target and the product, and lower doses are common. Specify the maximum you accept rather than assuming the legal ceiling is the working figure.
The untreated route needs its own controls. Choosing no treatment is a legitimate decision and it is not a passive one. It requires intake testing against your own limits, a validated downstream kill step, and segregation so that untreated material does not reach a ready-to-eat line by accident.
FAQ
Is irradiated spice safe to eat?
The authorised treatment is subject to a dose limit, a facility approval regime and a labelling requirement, and it has been assessed by the relevant scientific bodies as part of that authorisation. The practical question for a buyer is not safety in the abstract but market acceptability: your customer’s specification decides whether you can use it, and in EU retail that specification frequently says no. Treat it as a commercial constraint rather than a safety debate.
How can I tell whether a spice has been irradiated?
By the declaration, which is mandatory under Directive 1999/2/EC and has to appear in the ingredient list where an irradiated ingredient is used. Beyond the paperwork, standardised analytical methods exist for detecting irradiated foods, and official control laboratories apply them. That means a false declaration is a detectable fraud, which is a useful thing to know when assessing supplier risk. Do not rely on the absence of the Radura symbol; the EU obligation is the wording, not the logo. What the Radura symbol means covers the distinction.
Does steam treatment ruin the flavour?
It reduces it, measurably, and by more than irradiation at an equivalent microbiological reduction. How much depends on the species, on the process parameters and on how well the re-drying step is controlled. On green leaf material the colour change is often more noticeable than the aroma change. In practice the loss is acceptable for most cooked applications and is a real consideration for high-value aromatic species used in cold or finishing applications. Ask the supplier for before and after volatile oil figures on the same lot; a plant running a controlled process will have them. How steam sterilisation works sets out the process.
Can I sell an irradiated ingredient in an organic product?
No. Irradiation is not permitted under the EU organic regulation, and the incompatibility runs through to the finished product. If a programme is organic, the decontamination route is steam or nothing.
What should the clause actually say?
Name your position, the verification and the consequence. For a non-irradiation position: the material shall not have been treated with ionising radiation, supported by a supplier declaration per lot, with treated material rejected. For an accepting position: treatment permitted up to a stated maximum overall average absorbed dose, at a Union-approved facility identified by reference, with the declaration provided in the documentation and reflected in the labelling data. Either way, state which microbiological limits apply and separate the legal criteria from your own process hygiene levels. Irradiation rules for spices in the EU sets out the legal framework in full.