Overview of Grain Components and Changes Occurring in Grain Constituents with Different Forms of Processing
Grains are seeds that humans rarely consume without some form of prior processing. Cooking and commercial processing generally improve their digestibility, increase the bioavailability of nutrients, reduce the presence of natural toxicants and anti-nutritional factors, and create palatable flavors and textures. Removal of the outer bran layer decreases the dietary fiber content and may also remove antioxidants and micronutrients. Wet cooking processes can leach water-soluble vitamins, minerals and viscous fibers such as beta-glucans. Thiamine and lysine may be reduced in high-temperature processing, such as roasting and extrusion, whereas acrylamide and Maillard compounds responsible for desirable flavors and aromas may be created during those processes. Fortification and enrichment with nutrients are not discussed. The design of new cereal products should consider processing-induced changes in nutritional composition.