The
germ of a
cereal is the reproductive part that germinates to grow into a plant; it is the
embryo of the
seed. Along with
bran, germ is often a
by-product of the
milling that produces refined grain products.
Cereal grains and their components, such as
wheat germ oil,
rice bran oil, and
maize, may be used as a source from which
vegetable oil is extracted, or used directly as a food ingredient. The germ is retained as an integral part of
whole-grain foods. Non-whole grain methods of milling are intended to isolate the endosperm, which is ground into flour, with removal of both the husk (bran) and the germ. Removal of bran is aimed at producing a flour with a white rather than a brown color, and eliminating fiber: neither of these objectives is desirable from the nutritional viewpoint. Germ is rich in
polyunsaturated fats (which have a tendency to oxidize and become rancid on storage) and so germ removal improves the storage qualities of flour.