Corn is steeped in water mixed with sulfur dioxide and ground to separate germ from the endosperm to extract oil.
[2] Corn gluten meal as commonly produced contains "71.4% crude protein, 4.1% fat, 0.8% fiber, 1.2% ash, 12.4% starch, 10.1% other carbohydrates".
[3] The use of corn gluten meal as a preemergent[3] herbicide was patented in 1991,[4] but, like many food-related substances used for gardening, is not regulated in the US under 25(b).
Corn gluten meal is occasionally confused for corn gluten feed, which instead has approximately 22% crude protein and is a mixture of bran, steep liquor, and maize germ oil from the milling process.
[2] Corn gluten is used in the manufacture of hydrolyzed vegetable protein, a common food flavoring.