By Dustyn Cormier
Today we are going to dive into some chemistry! *Waits 10 seconds…* Now, for the 8 of you that are still reading, we are going to be talking specifically about enzymes. *Waits another 10 seconds…* For the 3 of you that stayed and decided that you are in for the long haul, we are going to be learning about amylase enzymes and the roles they play in the brewing process.
So, what is an enzyme? Well, I am glad that you asked, imaginary person in my head. Enzymes are specific types of proteins that play an important role in life and brewing because they catalyze biochemical reactions. Enzymes can join small molecules together to make larger molecules, they can break apart large molecules into smaller ones, and they can rearrange molecules into something completely different. Each biochemical reaction is catalyzed by a specific enzyme because each enzyme has a specific shape that is suited to that enzyme’s assigned task. This shape can be affected by certain factors, such as heat or agitation. When the shape of the enzyme is damaged, which is called denaturation, the enzyme will no longer be able to catalyze a reaction.
When it comes to brewing, amylase enzymes play a major role in the mashing process. There are several different amylase enzymes, including ptyalin, which is an amylase enzyme present in your saliva that begins the digestion process by breaking down some simple starches (this is largely the reason why things like crackers will break down and dissolve in your mouth). In the mash, we are really concerned with two main enzymes: alpha and beta amylase. These two enzymes work in consort to do the bulk of the converting and drawing out of sugars from the malt.
Alpha amylase is responsible for breaking down large, complex, insoluble starch molecules into smaller, soluble molecules. It will convert starch to soluble sugars in a temperature range from 145 to 158 °F. Beta amylase is mostly responsible for creating large amounts of fermentable sugar. It breaks down starch into maltose, which is easily fermentable by yeast. It is typically active between131 and 149 °F. As your mash approaches 149 °F, the beta amylase is working at its fastest, but it is also denaturing rapidly.
So, what can we do during mashing to affect these enzymes? Well, that’s another great question, imaginary person in my head. There are 4 main ways that we can alter the levels of these enzymes in our wort. The first and, arguably, most important way is via our mash temperature. These 2 enzymes have different optimal temperature ranges with a small window of overlap (145-149). A lower temperature mash will create more beta amylase, which will create a wort that is more fermentable, but may yield slightly less extract and have less body. A higher temperature mash will yield less fermentability, but increased extract efficiency and more body due to the larger, unfermentable sugars left in the wort. If you are aiming for a mash temperature above 149 and you utilize a single-infusion mash, then you run the risk of denaturing the beta amylase very quickly and diminishing its effects. If you are planning on mashing at a higher temperature, then you could opt to do a beta amylase rest within the enzyme’s optimal temperature range to increase the wort’s fermentability before raising the temperature into alpha amylase’s optimal temperature range.
The second way that we can affect enzyme actions in our mash is through the mash pH. The optimal pH for alpha amylase is 5.3-5.7 while the optimal range for beta amylase is 5.1-5.3. Adding acid, calcium ions, or using acidulated malt can help bring your mash pH down into the optimal ranges for these enzymes. Mash thickness can also play a role in amylase enzyme action. A thicker mash can add some temperature insulation for the beta amylase, while a thinner mash will result in alpha amylase being more prominent.
The last way that we can affect these enzyme actions is by adding commercially available, food-grade amylase enzymes directly to the mash. Enzyme concentration plays a large role in the rate at which the chemical reactions occur. Adding amylase enzymes to your mash will increase the rates of these reactions by providing more enzymes to break down sugars before total denaturation occurs. Adding amylase enzymes can be helpful when brewing a beer that utilizes a large percentage of specialty malts that have been kilned at high enough temperature to denature most of the natural amylase enzymes typically found in barley. Dosage rates can vary, but about .25 oz per 5 gallons of wort is typical.
Not everybody loves chemistry, but it is so important in the brewing process. Brewing is chemistry. Having at least a basic understanding of the different chemical reactions that occur throughout the mashing, boiling, and fermenting stages can greatly improve the quality and consistency of the beers that you brew. Understanding how the amylase enzymes work and their optimal environments can go a long way towards helping you to hit the numbers you are aiming for when brewing a specific style of beer.
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