Steam sterilisation vs ETO for spices: a guide for EU buyers

After reading this you will be able to explain why EU buyers insist on ETO-free spices, judge what steam sterilisation will and will not do to a lot, and list the documents to ask your supplier for before you sign.

Why ethylene oxide became a problem

Ethylene oxide (ETO) is a gas that kills bacteria and moulds. For many years it was used in several producing countries to cut the microbial load of spices, herbs and some food additives. It is not approved for use on food in the EU, and residues are controlled under the EU pesticide residue rules (Regulation (EC) No 396/2005).

Two details matter for buyers:

• The EU residue definition is the sum of ethylene oxide and 2-chloroethanol, expressed as ethylene oxide. 2-chloroethanol is a reaction product that can stay in the spice after the gas has gone. A lab report that tests for ETO alone is incomplete.
• For spices the maximum residue level is 0.1 mg/kg, set at the limit of quantification. In practice, a lot treated with ETO is likely to fail.

In 2020, ETO was found in sesame seeds from India at levels far above the EU limit. This led to large recalls in Europe, tighter import checks on Indian sesame and, later, special import conditions on some other Indian products, including certain spices. Since then "ETO-free" has been a standard line in EU spice contracts.

In April 2024, food safety authorities in Hong Kong and Singapore reported ETO in certain spice-mix products from Indian brands, and some products were withdrawn from sale or recalled. In May 2024 the Spices Board India issued guidelines telling exporters not to use ETO at any stage of the chain, to treat it as a hazard in their HACCP plans, to test raw materials, packaging and finished goods, and to use alternatives such as steam sterilisation or irradiation. Separately, the Spices Board already requires pre-shipment ETO testing for some product groups bound for the EU, such as spice mixes.

What steam sterilisation does

Steam sterilisation exposes the spice to saturated steam, typically somewhere between 100 °C and 125 °C, for a short time. The product is then dried back to its target moisture and cooled. Plants use batch vessels or continuous screw and belt systems. Settings are tuned per spice, because a black pepper berry and a fine chilli powder behave very differently.

Microbial load

The reduction depends on the spice, the starting load and the settings. In published trials on paprika powder, saturated steam at 108–125 °C for 20–120 seconds brought the total plate count down by about 2.5 logs (roughly from 10^5 to under 10^3 cfu/g), and moulds fell below the detection limit. Many buyers go further and ask for a process validated to a stated log reduction of Salmonella, commonly 5 logs.

Spec figures vary by buyer and spice. Commonly seen post-treatment targets look like this:

The European Spice Association treats Salmonella as a must-be-absent organism and recommends a maximum water activity of 0.65 for dried spices.

Flavour, colour and moisture

• Volatile oil. Some top notes are lost, most visibly in fine powders. Whole seeds and berries keep more of their oil because it sits inside the seed. Ask for volatile oil (ml/100 g) before and after treatment on the first lots.
• Colour. In the paprika trials above, colour shifted only slightly and the ASTA colour value did not fall. Results differ by plant and spice, so check ASTA colour for chilli and curcumin for turmeric on treated samples.
• Moisture. Steam adds water. A good line dries the product back to spec. A poor one leaves moisture that later causes caking or mould.
• Texture. Powders can clump. Many processors sterilise whole spices first and grind afterwards under hygienic conditions. This protects flavour, but the grinding room must not recontaminate the product.

How the options compare

Irradiated spices sold in the EU must be labelled as irradiated, including when they are an ingredient. Most retailers avoid this, which is why steam is the default.

Documents to request

Ask for these per lot, tied together by the same lot or batch number:

• Certificate of analysis from an ISO/IEC 17025 accredited lab, covering ETO and 2-chloroethanol by GC-MS/MS with a limit of quantification well below 0.1 mg/kg.
• Steam sterilisation record: plant name, date, batch, temperature, contact time and throughput. For a new supplier, ask for the validation summary for that product.
• Microbiology report after treatment: TPC, yeasts and moulds, E. coli, Salmonella.
• Pesticide residue screen against EU MRLs.
• Mycotoxins where relevant: aflatoxins and ochratoxin A for chilli, turmeric, ginger, nutmeg and pepper.
• Written declaration that ETO is not used anywhere in processing, storage, transport or packaging.
• Phytosanitary certificate, and if the container is fumigated, a fumigation certificate that names the fumigant. Fumigation against insects is a separate step from sterilisation.
• Any official certificate or test report required by the special import conditions in force for that product.

Practical points

• Test after the last step. If a spice is steam-treated whole and then ground, the ETO and micro results should be on the final ground lot.
• Keep retention samples. Both sides should hold sealed samples from the shipped lot.
• Put it in the contract. State "ETO-free, sum of ETO and 2-chloroethanol below 0.1 mg/kg", the micro limits and the lab you accept for disputes.
• Plan time. Steam sterilisation and lab results add days before stuffing. Build that into the shipment date.

Before you order

• Is ETO plus 2-chloroethanol in the spec, with the method and LOQ?
• Is the sterilisation method named, with a treatment record per lot?
• Are micro limits and the sampling plan agreed?
• Are pesticide and mycotoxin tests listed for this spice?
• Does every document carry the same lot number?

If you're buying steam-treated spices for the EU, send us the spice, form (whole or ground), spec and destination port, and we'll come back with a written quote and the test plan we would follow.