Sodium stearoyl lactylate is a chemical compound, ester of the reaction of stearic acid with lactic acid and sodium.

The name defines the structure of the molecule:

• Sodium is a chemical element with the symbol Na (from the Latin "Natrium") and the atomic number 11. In the context of Sodium Stearoyl-2-Lactylate, it indicates the presence of a sodium salt.
• Stearoyl refers to the presence of a group of Stearoil in the compound, a derivative of stearic acid, a saturated fatty acid commonly found in animals and vegetable fats. It consists of a carbon 18 chain with a carboxyl group (-COOH) at one end.
• Lactylate Lactates are esters derived from lactic acid, which is a natural organic acid and are commonly used as food additives and emulsifiers due to their ability to stabilize emulsions and improve consistency.

The synthesis process takes place in several stages:

• Preparation. Stearic acid is a long chain fatty acid that can be obtained from fats and oils through the saponification process with subsequent isolation.
• Esterification. Stearic acid is introduced into a reaction with lactic acid in the presence of a catalyst to form Stearoil-2-lactylate.
• Neutralization. Stearoyl-2-lactylate is neutralized with a base of sodium hydroxide (NaOH) to form the sodium salt, which will produce Stearoil-2-lactylated sodium.

It appears in the form of a white powder.

What it is used for and where

Food

It is included in the list of food additives with the number E481 as a hydrophilic emulsifier, thickener, stabilizer.

Cosmetics

• Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable and are used to soothe or soften the skin and emulsify, so they need a specific, stabilising ingredient. This ingredient forms a film, lowers the surface tension and makes two immiscible liquids miscible. A very important factor affecting the stability of the emulsion is the amount of the emulsifying agent. Emulsifiers have the property of reducing the oil/water or water/oil interfacial tension, improving the stability of the emulsion and also directly influencing the stability, sensory properties and surface tension of sunscreens by modulating the filmometric performance.

Safety

EFSA's Scientific Panel on Food Additives provided a scientific opinion on the safety of sodium stearoyl-2-lactylate (E 481, SSL) and calcium stearoyl-2-lactylate (E 482, CSL) when used as food additives. Neither SSL and CSL nor their breakdown products stearic and lactic acid raise concern for genotoxicity. The NOAEL in a one-year oral toxicity study with SSL in rats was 2214 mg/kg bw/day for males and 2641 mg/kg bw/day for females. No data on reproductive toxicity and carcinogenicity were available. However, no reproductive or carcinogenic effects are expected since the products of hydrolysis, stearic and lactic acid are constituents of natural food and part of endogenous metabolism in mammals. The Panel concluded that based on the NOAEL of 2200 mg/kg bw/day derived from the one-year toxicity study in rats and an uncertainty factor of 100, an ADI of 22 mg/kg bw/day for sodium stearoyl-2-lactylate (E 481) and calcium stearoyl-2-lactylate (E 482) either singly or in combination can be established. The estimated exposure to SSL and CSL occurs mainly via the consumption of flavoured fermented milk products including heat treated products, bread and rolls and fine bakery wares and is below the ADI of 22 mg/kg bw/day for all the adult population including the elderly, but exceeds the ADI for other groups of the population at mean level and for all groups of the population at high level (1).

This substance is used in the following products:

• foodstuff
• biocides
• disinfectants
• pest control products
• inks and toners
• perfumes and fragrances
• pharmaceuticals
• washing & cleaning products
• cosmetics and personal care products

It is included in the list of food additives with the number E481 as an anionic emulsifier and also performs the functions of hydrophilic emulsifier, thickener, stabilizer.

Sodium stearoyl lactate is non-toxic and biodegradable (2).

Sodium stearoyl lactate studies

• Molecular Formula: C₂₄H₄₃NaO₆
• Molecular Weight: 450.592 g/mol
• UNII: IN99IT31LN
• CAS: 25383-99-7
• EC Number: 246-929-7

Synonyms:

• Sodium stearoyl-2-lactylate
• SSL
• E481
• Sodium stearoyl lactylate
• Sodium 2-((2-(stearoyloxy)propanoyl)oxy)propanoate
• Sodium stearyl-2-lactylate
• sodium 2-{[2-(stearoyloxy)propanoyl]oxy}propanoate
• Lactic acid, bimol. ester, stearate, sodium salt
• Octadecanoic acid, 2-(1-carboxyethoxy)-1-methyl-2-oxoethyl ester, sodium salt (1:1)
• Octadecanoic acid,2-(1-carboxyethoxy)-1-methyl-2-oxoethyl ester, sodium salt (1:1)
• Sodium 2-(1-carboxyethoxy)-1-methyl-2-oxoethyl octadecanoate
• Stearic acid, ester with lactic acid bimol. ester, sodium salt
• sodium stelate
• sodium 2-stearoyllactylate
• Sodium 2-(2-octadecanoyloxypropanoyloxy)propanoate
• sodium alpha-(alpha-(stearoyloxy)propionyloxy)propionate
• sodium 2-(1-carboxyethoxy)-1-methyl-2-oxoethyloctadecanoate
• sodium 2-(1-carboxylatoethoxy)-1-methyl-2-oxoethyl stearate
• stearic acid ester with lactic acid bimol. ester sodium salt
• stearic acid, ester with lactate of lactic acid, sodium salt
• stearoyl-2-lactylic acid, sodium salt
• Octadecanoic acid, 2-(1-carboxyethoxy)-1-methyl-2-oxoethyl ester, sodium salt
• Sodium 2-stearoyllactate
• SCHEMBL156076

References_________________________________________________________________

(1) EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), 2013. Scientific Opinion on the re‐evaluation of sodium stearoyl‐2‐lactylate (E 481) and calcium stearoyl‐2‐lactylate (E 482) as food additives. EFSA Journal, 11(5), p.3144.

(2) Kaur K, Kaur J, Kumar R, Mehta SK. Formulation and physiochemical study of α-tocopherol based oil in water nanoemulsion stabilized with non toxic, biodegradable surfactant: Sodium stearoyl lactate.    Ultrason Sonochem. 2017 Sep;38:570-578. doi: 10.1016/j.ultsonch.2016.08.026.