Zein

• USP–NFZein

corn gluten protein; maize prolamin; zea mays prolamine

Prolamine protein obtained from maize (Zea mays) · [9010-66-6]

Polymer, mixture or material of variable composition — no single molecular formula applies.

Coating agent, film former

Typical concentrations: — · Dosage forms: Solid

Used as a tablet coating agent (film coats, moisture-barrier and sustained-release coats), as a binder in wet granulation where it is added as an aqueous-alcoholic solution, and as a matrix former in sustained-release tablets and microparticles. It is also used to make micro- and nanoparticles for drug delivery, in edible coatings for foods and confectionery, and as a glaze. Use levels depend on the coating or matrix design.

A white to yellow, odourless powder or granules. It is a mixture of alcohol-soluble storage proteins (prolamins) of maize, rich in glutamine, leucine, proline and alanine and poor in lysine and tryptophan.

Solubility

soluble in aqueous ethanol (roughly 60–90% v/v), aqueous acetone and glycols, and in aqueous alkali at high pH; practically insoluble in water and in anhydrous ethanol

Film properties

hard, glossy, grease-resistant films; brittle unless plasticised

Nature

hydrophobic protein; main fraction (α-zein) consists of polypeptides of about 19–22 kDa

Stable when stored in a well-closed container in a cool, dry place. Films become brittle as plasticiser is lost or with ageing, so a plasticiser is normally included.

Incompatible with strong oxidising agents.

Extracted from corn gluten meal, a by-product of maize wet milling, with aqueous alcohol (such as aqueous isopropanol or ethanol); the extract is purified and the protein is recovered by precipitation or evaporation and dried.

Used in foods and oral medicines and regarded as non-toxic. It is digested like other dietary proteins. People with maize allergy may react to it, though such reactions are uncommon.

Observe normal precautions for the quantity handled. Eye protection and a dust mask are recommended. Its alcoholic coating solutions are flammable.

GRAS listed. Included in the FDA Inactive Ingredient Database (oral tablets).

Shellac; ethylcellulose; maize starch.

Zein is a plant-derived alternative to shellac for glazes and protective coatings. Because coating solutions use aqueous ethanol, solvent recovery and flammability must be managed; aqueous dispersions and alkaline solutions have been studied as alternatives.