Tips & Tidbits - Enzymes in the Mash
Enzymes are proteins that facilitate chemical reactions. The creation and utilization of enzymes in brewing occurs naturally during the malting and mashing process. Although enzymes are not living organisms, they are triggered to react under appropriate conditions and deactivated or denatured by conditions they cannot tolerate. Enzymes magically convert a starchy mash into sweet liquor.
During the mash all the enzymes operating at different temperatures are involved in chopping up longer molecules directly influencing the flavor of the finished beer.
Protease or proteolytic enzymes are protein degrading enzymes which break down long, complex chains of protein molecules. Proteolytic enzymes break down nitrogen based proteins into amino acids which are valuable yeast nutrients at 113-122 degrees F. Other proteolytic enzymes work to break up larger proteins which enhance head retention and aid clarity at 122-140 degrees F. The time in the mash when the proteolytic enzymes are activated is called the protein rest.
Next begins the work of the diastatic enzymes which covert starch molecules to fermentable sugars and unfermentable dextrins hence the term saccharification rest. Starch molecules are basically long chains of very fermentable glucose molecules, but because they are attached they are not fermentable. A very fermentable chain of two glucose molecules linked together is called maltose.
Dextrins are a chain of four or more glucose molecules which resulted from starch break down. They are not fermentable and tasteless yet contribute a creamy mouthfeel and fuller body to the beer.
During saccrification there are two enzymes at work, alpha amylase and beta amylase. Alpha amylase breaks down the long chains of glucose molecules by chopping them randomly into shorter and shorter chains at temperatures of 149-162 degrees F. Beta amylase is a nibbler working from the ends of the starch molecule at temperatures of 126-149 degrees F. biting off one maltose sugar at a time. Conversion from starch to sugar will occur more quickly if there are more ends for the beta amylase to nibble. So with the alpha amylase chopping up the starch molecules, these two enzymes work together during the mash to produce both fermentable and unfermentable sugars.
The alpha amylase and beta amylase enzymes will work well together at temperatures between 145-158 degrees F. A higher mash temperature, greater than or equal to 156 degrees F. will dextrinous wort in a short, active period of time resulting in a less fermentable, sweeter beer. A lower temperature mash, less than or equal to 150 degrees F., will produce a more fermentable wort over a longer period of time. The resulting beer will be thinner bodied creating more alcohol given the same original gravity as a dextrinous wort.