Ethanolic extraction of zein from maize

Zein can be extracted from maize (Zea mays) using ethanol solutions, and recovered from the extract by diluting with water. Dilution to 40% ethanol will precipitate a mixture of zein and maize lipid with 15% lipid. For possible zein applications, such as film production, purer zein is required. Most of the lipid can be removed from the precipitate by selective re-extraction with hexane or ethanol, but this is expensive. A precipitate containing 90% or more of the protein in the extract, with less than 10% lipid, can be obtained by diluting the extract in stages. An initial dilution will precipitate a solid with 75% or more lipid, this precipitate can be centrifuged from the extract and the centrifugate diluted to precipitate a solid of 70% or more zein. The mass and composition of solid centrifuged from a maize extract that was diluted in several steps to characterize the composition of precipitates so formed. The lipid content of a zein product precipitated from an extract diluted from 55% ethanol to 50% is significantly lower than the content of precipitate of an extract diluted in a single step to 40% ethanol. Published by Elsevier Science B.V.