Maize Germ

Degermination separates the germ from the endosperm by exploiting a difference in physical behaviour rather than by cutting it out. Tempering with water makes the germ tough and rubbery while the endosperm stays brittle, so a degerminator that shears the kernel breaks the endosperm into pieces while the germ survives largely intact. It can then be separated by size, density, and aspiration, because a whole germ behaves quite differently in an air stream from a chip of endosperm.

Germ goes to oil. It is pressed, solvent-extracted, or both, to recover corn oil, which is refined into a widely used cooking and food-manufacturing oil. What remains after the oil is taken out — corn germ meal — retains protein and fibre and is sold as a feed ingredient, so the stream is used twice over. Germ is also used directly in feed where oil extraction is not available or not economic, and stabilised germ appears as a food ingredient in a small way.

• Oil — the principal raw material for corn oil extraction
• Feed — corn germ meal after extraction, and whole germ where extraction is not economic
• Food — stabilised germ as a minor ingredient

Germ is bought on oil content and on how cleanly it was separated: adhering endosperm and bran dilute the stream and lower its value to an extractor. Free fatty acid content matters too, and it is a moving target — germ carries active lipase alongside its oil, and once the kernel has been broken open the two are in contact. Germ that sits warm and damp before extraction degrades measurably, so the interval between the degerminator and the press is a quality variable in its own right.

The same reasoning applies to storage. Germ is dried, kept cool, and moved on rather than held, and mycotoxins present in the incoming maize can partition into the germ fraction, so the safety status of the grain follows the stream. Bulk handling is straightforward — germ is light, flaky, and free-flowing — but its oil makes dust and residues in conveying equipment a housekeeping matter.