Enzyme activity during germination of different cereals: A review

The germination process increases enzymatic activity. However, this does not occur in the same way in all cereals. It depends on the type of enzyme, the cereal, and the conditions of germination. During germination, most enzymes are localized in the aleurone layer and the scutellum. Some of them, such as xylanases, proteases, and beta-glucanases, are also localized in the endosperm while beta-glucanases and lipases have been identified in the embryo. The maximum activity of the enzymes in most cereals start from day 4 of germination. Germination allows the hydrolysis of macromolecules and compounds like beta-glucans and phytic acid. In cereals, starch is the component that presents the most morphological changes. Germination mobilizes and increases the activity of some enzymes. Temperature, steeping time, and variety are determining factors in the activation time. At higher temperatures, the enzymatic activation is generally faster; however, there are some exceptions. The use of germination could be a promising resource for modifying grain properties and increase enzymatic activity; also, this process is simple and economical.