Zein is a prolamine powder, derived from corn gluten
. It is odorless
, and tasteless
(but in a good way). It is commonly used as a harmless glaze
in foods and pharmaceutical products.
Because it is manufactured physically, without any chemical processes, zein is labelled as a food ingredient, not an additive. It resists bacterial attack and repels some grain-interested insects, and is used as a food coating for that reason.
It is often mixed with dyes and flavorings as a coating for jelly beans, dried fruits, enriched rice, nuts, and various types of drug capsules and pills. It offers a better coating than traditional confectioner's glaze, and has the added benefits of extended shelf-life, and is not derived from imported insect-based organic acids.
It is sometimes seen on product labelling as Corn Protein Glaze, or Vegetable Protein Glaze.
Zein was first isolated in 1821. It was used in a purely experimental role until 1939 when it became commercially available. Until the 1960s, zein was used for a wide range of coatings, including the insides of beverage containers, photographic film, and also as an ingredient in edible inks.
It is made up of 16 amino acids:
Glutamic Acid and Glutamine 20-22 percent
Leucine 17-20 percent
Alanine 8-10 percent
Proline 5-9 percent
Phenylalanine 4-7 percent
Isoleucine 3-7 percent
Serine 4-6 percent
Tyrosine 3-5 percent
Asparagine 4-5 percent
All others less than 3 percent
Within the corn kernel it occurs as a heterogenous mixture of disulfide linked aggregates. After mechanical extraction, the proteins are diluted in aqueous alcohol solution, and then evaporated to form a clear film.
It's mostly harmless.