Sr-Methionyl Cow Alpha-S1-Casein
A cosmetic ingredient used as skin conditioning - emollient, surfactant - emulsifying, surfactant - foam boosting in skincare, haircare, and personal-care products sold in the European Union.
What is it?
sr-Methionyl Cow Alpha-S1-Casein is a single chain protein produced by fermentation in E. coli. The starting gene is synthetically produced to be identical to Alpha-S1-Casein which is found in the Bos taurus (cow) with the initiation code for methionine. The protein contains 214 amino acids which may contain disulfide bonds and/or glycosylation, and consists of the proper sequence of the 20 standard amino acids.
What does it do?
Sr-Methionyl Cow Alpha-S1-Casein is listed in the EU cosmetic ingredient inventory with the following declared functions:
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Skin conditioning - emollient
softens the skin by reducing roughness and friction between skin cells
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Surfactant - emulsifying
surfactant that forms and stabilises emulsions of oil and water — without it, creams and lotions would separate
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Surfactant - foam boosting
surfactant that increases the volume or stability of foam produced by other surfactants in the same formulation
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Hair conditioning
improves the appearance, feel, and manageability of hair
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Skin conditioning - occlusive
forms an occlusive layer on the skin to slow water loss, complementing humectants
EU regulatory status
Sr-Methionyl Cow Alpha-S1-Casein is allowed for use in cosmetic products in the European Union under Regulation 1223/2009. It is not subject to a specific Annex restriction at the time of writing.
Frequently asked questions
What is Sr-Methionyl Cow Alpha-S1-Casein?
Sr-Methionyl Cow Alpha-S1-Casein is a cosmetic ingredient catalogued in the EU CosIng database. sr-Methionyl Cow Alpha-S1-Casein is a single chain protein produced by fermentation in E. coli. The starting gene is synthetically produced to be identical to Alpha-S1-Casein which is found in the Bos taurus (cow) with the initiation code for methionine. The protein contains 214 amino acids which may contain disulfide bonds and/or glycosylation, and consists of the proper sequence of the 20 standard amino acids.
Is Sr-Methionyl Cow Alpha-S1-Casein allowed in cosmetics in the EU?
Yes. Sr-Methionyl Cow Alpha-S1-Casein is allowed for use in cosmetic products in the EU under Regulation 1223/2009.
What does Sr-Methionyl Cow Alpha-S1-Casein do in cosmetic products?
Sr-Methionyl Cow Alpha-S1-Casein is declared in the EU cosmetic ingredient inventory with these functions: skin conditioning - emollient, surfactant - emulsifying, surfactant - foam boosting, hair conditioning, skin conditioning - occlusive.
Related ingredients
Source: EU CosIng database (European Commission). This page is derived from public-sector information published by the European Commission. · Last updated: 25/06/2026