Irradiation vs Steam Sterilisation for Botanical Powders: Methods, Labelling Rules and What to Specify

KUALA LUMPUR, 31 JULY 2026 —

Irradiation, ethylene oxide fumigation and saturated steam all reduce microbial load in botanical powders — but the law and the market treat them very differently. Ethylene oxide is not authorised for food in the EU, irradiated ingredients must be declared on the label, and steam is the mainstream compliant route. The strongest position of all is not needing a terminal treatment, because bioburden was controlled upstream.

Extraction and spray drying reduce that load but were never designed as a kill step, so many manufacturers apply a terminal treatment to bring the finished powder inside specification — typically total plate count, yeast and mould, coliforms, and the absence of E. coli and S. aureus in a defined sample weight.

The question a buyer should ask is not whether a treatment was applied, but which one — because the answer determines whether the ingredient can be sold, and how it must be labelled.

Ionising radiation — gamma rays from a cobalt-60 source, or accelerated electrons — damages microbial DNA without meaningfully raising the temperature of the product. It is effective, it treats material inside its final packaging, and because it is a cold process it is gentler on heat-sensitive constituents than steam. On technical grounds alone it is an attractive method.

The problems are legal and commercial. In the European Union, only dried aromatic herbs, spices and vegetable seasonings are authorised for irradiation at Union level; treatment must be performed at an approved facility; and, decisively, the ingredient must be declared as irradiated or as treated with ionising radiation . That declaration follows the ingredient into the finished product’s labelling. Japan effectively prohibits food irradiation other than for potatoes. Organic certification schemes exclude it outright.

And a large share of clean-label brand owners simply will not buy it, whatever the regulation permits.

So irradiation is best understood as a method that works but narrows your market. If you are formulating for a single permissive market and price is the binding constraint, it may be defensible. If you are exporting, or building a premium or clean-label position, it closes doors.

Ethylene oxide is a gaseous fumigant, highly effective against bacteria, moulds and spores, and still used in some producing regions for spices and botanicals. It is not authorised for food use in the European Union , and its residues — including the breakdown product 2-chloroethanol, which persists far longer than the parent gas — have driven repeated rapid-alert notifications, border rejections and multi-country recalls of botanical ingredients and the finished products containing them.

Unlike irradiation, this is not a labelling question. An EtO-treated ingredient that reaches the EU is a non-compliant ingredient, and the liability lands on whoever placed the finished product on the market. Any serious sourcing specification should therefore state explicitly that the material has not been treated with ethylene oxide, and back it with residue testing where the origin or the supply chain gives cause for doubt.

Saturated steam sterilisation exposes the material to controlled steam under vacuum for a short, defined time, then dries and cools it. It is the mainstream compliant route: no treatment declaration is required on the label, it is accepted across export markets, and it is compatible with organic certification when the process is approved.

The trade-off is heat and moisture. Volatile aromatics can be driven off, heat-labile constituents degraded, pigments shifted, and the powder’s moisture and flow properties changed if the drying stage is not properly controlled. This is why an over-applied steam cycle is as much a quality failure as an untreated lot.

A competent treatment is validated for the specific material, kept as short as the microbial target allows, and followed by re-assay of the marker compound so that the buyer can see what the treatment cost in potency.

Terminal treatment is a correction. It is applied because the microbial load arriving at the end of the line is higher than the specification allows. The alternative — harder to build, cheaper to run, and invisible on a label because there is nothing to declare — is to keep the load low all the way through:

Where this is done well, the finished extract meets its microbial specification without any terminal treatment — which is the cleanest answer a buyer can be given.

Bionutricia does not apply irradiation as a processing step. Microbial control inside our own plant is designed into the process under our certified systems — FSSC 22000, GMP, HACCP, JAKIM Halal, US FDA registration and MeSTI, together with NanoVerify certification — at our Sungai Buloh, Selangor facility, rather than being applied as a terminal correction at the end of the line.

Treatment status is a specification matter rather than an assumption. Where a buyer requires a particular status, it should be written into the specification for the individual material and confirmed for that product, and we will confirm the position for any product on request.

Our patented enzymatic and ultrasonic extraction process (MY-188945-A) is designed for high, controlled active yield under defined conditions, which supports both potency and consistent microbial performance lot to lot. Every batch is released against a Certificate of Analysis carrying the full microbial panel.

Bionutricia supplies the bulk ingredient for B2B formulation; brand owners and manufacturers formulate it into their chosen finished format — capsules, tablets, sachets, beverages, bakery, dairy or confectionery — and specification and documentation packs are available to qualified buyers on request.

Need confirmation of treatment status for a specific extract?

It is legal in many markets but tightly controlled. In the EU only dried aromatic herbs, spices and vegetable seasonings are authorised at Union level, treatment must be carried out at an approved facility, and the ingredient must be declared as irradiated or treated with ionising radiation. Several markets, including Japan, effectively prohibit it for foods other than potatoes.

In the EU, yes. An irradiated ingredient must be labelled irradiated or treated with ionising radiation, and the declaration carries through to the ingredient list of the finished product. That is why brand owners so often specify non-irradiated material even where treatment would be lawful.

Ethylene oxide is not authorised for food use in the EU and its residues, including the breakdown product 2-chloroethanol, have triggered repeated border rejections and recalls of botanical ingredients. Where irradiation is a labelling and acceptance issue, ethylene oxide is a compliance failure. Rule it out first.

It can. Saturated steam applies heat and moisture, and heat-labile constituents, volatile aromatics and some pigments will lose potency if the cycle is over-applied. A validated, short, controlled cycle followed by re-assay of the marker compound is what separates a competent treatment from a destructive one.

Bionutricia does not apply irradiation as a processing step. Treatment status is confirmed per material rather than assumed across the range, and we will confirm the position for a given product on request.