The germ of a cereal grain is the part that develops into a plant;[1] it is the seed embryo.[2] Along with bran, germ is often a by-product of the milling[3] that produces refined grain products. Cereal grains and their components, such as wheat germ oil,[4] rice bran oil, and maize bran,[5] 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.[6] 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 produces a flour with a white rather than a brown color and eliminates fiber. The 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.[7]
The embryo is that part of the seed that germinates and grows into the vegatative plant. In cereal grains, embryos (germs)...
...the germ or embryo of the grain...
There are two methods that are used for the dry-milling process: milling without removal of the cereal germ, the oldest method, and milling with removal of the cereal germ, the method most used today to ensure a better preservation.
Table: Vegetable Oil Stability [includes wheat germ]
In addition, some maize and rice bran are used to make vegetable oil.
Whole-grain flours are typically stone-ground or hammer-milled. Refined flours, from grains stripped of their bran and germ, must be milled with rollers.