Action of Enzymes
Little need be said about the action of enzymes, except that if temperatures during the mash tun and fermentation stages are not reasonably constant, enzyme action will not take place. Enzymes are biological catalysts; they bring about chemical changes essential in the production of good beers. Starches and other matter are converted to sugars, and flavor is produced; indeed, without their action we would not be able to make beers at all.
The temperature in the mash tun stage ensures that enzyme action takes place and a warm atmosphere during fermentation ensures that the yeast is happy. If too hot the yeast will be destroyed if too cold it will go dormant. Always allow the boiled wort to cool well - to about 70°f. if you have a thermometer - before adding the yeast and try to keep the fermenting beer at between 60° and 70°f. This will ensure a good ferment which is essential if good beers are to result.