Reviewed by Vitthia Rama Murti, Bionutricia
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.
Quick facts
- Four options: gamma or e-beam irradiation, ethylene oxide (EtO) fumigation, saturated steam sterilisation, or upstream bioburden control by process design
- EtO: not authorised for food use in the EU; a recurring cause of border rejections for botanical ingredients
- Irradiation: lawful only for authorised categories and approved facilities in the EU, and must be declared on the label
- Steam: broadly accepted and not subject to a treatment declaration, but must be validated to protect heat-labile actives
- Specify, don’t assume: require the treatment method to be declared for each material rather than inferred from a microbial result
Why botanical powders need microbial reduction at all
Dried botanicals arrive with a microbial history. They are grown in soil, harvested in the open, dried in ambient conditions and handled several times before they reach an extraction plant. Total plate counts in the hundreds of thousands per gram are ordinary for untreated dried herbs and spices, together with yeasts, moulds and spore-forming bacteria that survive drying comfortably.
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.
Gamma and e-beam irradiation
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 — the one to rule out first
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.
Steam sterilisation
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.
Comparing the three treatments
| Gamma / e-beam | Ethylene oxide | Saturated steam | |
|---|---|---|---|
| Microbial efficacy | High, including spores | Very high, including spores | High; spore reduction depends on cycle |
| Effect on heat-labile actives | Low (cold process) | Low | Moderate — must be validated |
| EU food-use status | Authorised for limited categories, approved facilities only | Not authorised | Permitted |
| Label declaration required | Yes — irradiated / treated with ionising radiation | n/a — not lawful | No |
| Organic compatibility | Excluded | Excluded | Generally compatible |
| Typical buyer acceptance | Often refused by clean-label and export buyers | Refused; a recall risk | Broadly accepted |
The fourth option: control bioburden upstream
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:
- Raw-material qualification. Incoming microbial screening, with rejection criteria, so a heavily contaminated lot never enters the process.
- Rapid, controlled drying and water-activity management. The same discipline that suppresses mould growth and mycotoxin formation suppresses bacterial proliferation.
- Closed processing and hygienic plant design. Zoning, filtered air and cleaned-in-place transfer lines prevent recontamination after the wet stages, which is where a surprising share of finished-powder counts originate.
- Extraction and drying conditions that carry inherent lethality. Temperature and residence time in the process itself do meaningful work when they are designed and validated rather than assumed.
- A HACCP plan under a certified food-safety system, with microbial limits as verified control points rather than as an end-of-line hope.
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.
What to put on your specification
| Specify | Why it matters |
|---|---|
| Not treated with ethylene oxide | Removes the single largest border-rejection and recall risk in botanical sourcing. |
| Not irradiated | Avoids a mandatory EU label declaration, preserves organic and clean-label eligibility and keeps Japan open — specify it at the raw-material stage, not only for the finished extract. |
| Treatment method disclosed, if any | If steam is used, you need to know — so the potency data can be read in that light. |
| Post-treatment assay of the marker compound | Proves the treatment did not quietly cost you the active you are paying for. |
| Full microbial panel on the finished extract | Total plate count, yeast and mould, coliforms, and absence of E. coli and S. aureus in a stated sample weight. |
| Batch-specific COA from an accredited laboratory | Ties the result to the lot you are actually receiving. |
Bionutricia’s position
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?
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Frequently asked questions
Is irradiated food legal?
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.
Does irradiation have to be declared on the label?
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.
Why is ethylene oxide a bigger problem than irradiation?
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.
Does steam sterilisation damage the actives?
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.
Does Bionutricia irradiate its extracts?
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.
