Development of enzymes during malting and their function in mashing.
The germination phase of malting represents the growth of a seed during which numerous enzymic reactions take place. The brewers' mash, on the other hand, is a simpler system in which some degree of control is available regarding substrate levels and relative enzyme activities. In this context some enzymes of interest to the maltster and brewer are discussed in relation to their occurrence during malting and their behaviour under mashing conditions. These enzymes are: respiratory enzymes, lipolytic enzymes, invertases, proteases, phytase, nucleases, amylolytic enzymes, and cytases. During early stages of germination the lipid reserves, hydrolysed by lipases are used as an energy source for the synthesis of other metabolites. The respiratory enzymes of the embryo provide the high energy compounds involved in these syntheses. Invertase systems provide sucrose hydrolysis which is part of the mechanism whereby sucrose is transported within the kernel prior to utilisation as an energy source. Proteases, formed in the aleurone cells and embryo , supply amino acids for the development of protein in new barley tissue and ultimately in the brewing phase, for yeast growth during fermentation. Phosphate, purines and pyrimidines are supplied to the seedling and ultimately in the mash through the action of phytase, nucleases and related enzymes. Cytases break down the starch cell walls to make the starch granules vulnerable to amylolytic action. In as much as starch is the predominent constituent of the brewers' mash, adequate amylolytic activity is essential in the process to produce maltose levels adequate for fermentation.
Keywords: brewing enzyme malting mashing survey