This page covers the EU rules on which solvents may be used in the production of algal extracts intended for food applications, and the residue limits that apply to such extracts once placed on the market.

Solvent extraction is central to the commercial production of many high-value algal products: pigment concentrates (phycocyanin, astaxanthin, fucoxanthin, chlorophyll), omega-3 oil fractions, polysaccharide preparations and algal protein concentrates are all commonly produced using solvent extraction at some stage of the process. The EU applies a positive-list system: a solvent not listed in the applicable Directive may not legally be used in food production or food ingredient production for the EU market, regardless of its safety profile.

European Parliament and Council Directive 2009/32/EC of 23 April 2009 on the approximation of the laws of the member states on extraction solvents used in the production of foodstuffs and food ingredients, OJ L 141, 6.6.2009, p. 3. EURlex

Relevance to algae: This Directive establishes the exhaustive positive list of substances that may be used as extraction solvents in the production of foods or food ingredients, together with:

• Permitted conditions of use — the food categories or production applications in which each solvent is permitted.
• Maximum residue levels in food or food ingredient as sold to the consumer or food manufacturer (expressed as mg of solvent per kg of food).
• Labelling requirements where residues above a threshold remain in the final product.

Solvents not listed in Annex I or Annex II of the Directive are not permitted for use in food production intended for the EU market, even where used for extraction of an otherwise compliant algal ingredient.

• Water and ethanol (food-grade ethyl alcohol) — listed in the Directive as permitted for use with no specific maximum residue level, provided they meet purity criteria. These are the broadest-use solvents and the most commercially relevant for producers seeking easy regulatory compliance; water (and rarely ethanol) extraction is used extensively in the production of phycocyanin from Spirulina and various polyphenol/polysaccharide extracts from seaweeds.
• Hexane — permitted for use in the production of certain fats and oils, including extraction of vegetable oils and the refining of olive oil. Algal oil producers (particularly those working with cold-press residues or dried biomass) may use hexane; maximum residue in the final product is 1 mg/kg. This is one of the more tightly controlled permitted solvents given hexane's known toxicity.
• Acetone — permitted for specific applications including carotenoid production; maximum residues apply.
• Carbon dioxide (supercritical CO₂) — listed as a permitted extraction solvent. Supercritical CO₂ extraction is increasingly used for high-value algal pigments (astaxanthin, fucoxanthin) and oil extraction given the absence of solvent residue concerns; it may not technically leave “residues” in the meaningful sense, but its use must nonetheless comply with the Directive's framework. It seems reasonable to use food-grade CO₂. Combinations like water, methanol or ethanol co-solvents are used - they are not mentioned in the directive as a combination.
• Ethyl acetate — permitted for specific applications; used in some carotenoid extraction processes.

Several solvents sometimes used in laboratory-scale algae research or in food ingredient production outside the EU — including certain chlorinated solvents, dimethyl sulfoxide (DMSO), and others (methanol has been added to the list in 2010) — are not on the EU permitted list and may not legally be used in the production of food ingredients for the EU market. Industrial producers should verify the status of any solvent used in their extraction process before assuming it is compliant. Some combinations of solvents (mainly with hexane) are explicitly forbidden.

At the time of writing, no switchable solvents, deep eutectic solvents, or ionic solvents (green or not) are on the list.

Where a specific extraction process is used to produce an algal ingredient, the process itself can be relevant to novel food status. Under Article 3(2)(a)(vii) of the Novel Food Regulation (EU) 2015/2283, a food is novel if it results from a production process not used before 15 May 1997 that gives rise to significant changes in the composition or structure of the food, affecting its nutritional value, metabolism or level of undesirable substances. A novel extraction process applied to an otherwise conventional algal species can therefore cause the resulting extract to be a novel food, even if the source species is not. The extraction solvent used is part of the production process definition for this purpose.

This means that for algal extracts:

• The choice of solvent is a compliance question under the Extraction Solvents Directive;
• The novelty of the process (including the solvent used and extraction conditions) may simultaneously trigger a novel food assessment under Regulation (EU) 2015/2283.

Both analyses must be completed before market access can be confirmed. See Novel Food for the novel food framework.

For products seeking organic certification (see Organic Production and Other Certifications), additional restrictions apply. Organic certification under Regulation (EU) 2018/848 imposes more restrictive rules on processing aids and solvents permissible in organic processing. In particular, the permitted inputs for organic processing are listed in Annex VIII to that Regulation, and not all solvents on the positive list of the Extraction Solvents Directive are simultaneously permitted for organic processing. Producers of organic-certified algal extracts should verify compliance with both frameworks.

• Positive list only — verify that every solvent used in the extraction chain is on the EU permitted list before committing to a production process.
• Residue limits in the final product — even where a solvent is permitted, the residue in the food as sold must not exceed the Directive's maximum; this requires analytical verification for solvents with tight limits (notably hexane).
• Supercritical CO₂ is a safe choice from a regulatory standpoint and is increasingly preferred for premium-positioned algal extracts precisely because residue concerns are eliminated.
• Combining solvent choice with novel food analysis — new extraction processes (new solvent combinations, new conditions) should be reviewed for potential novel food implications at the same time as the solvent compliance check.
• Export markets — solvent residue standards outside the EU (Japan, USA, etc.) may differ; if the product is intended for multiple markets, check requirements in each.

See also: Food | Novel Food | Food Additives | Organic Production and Other Certifications

Last reviewed: June 2026.