Step Mashing in Beer Brewing – What Is It and Why?
Step mashing is a brewing technique where the mash temperature is gradually increased through a series of rests. In this article, we explore step mashing: what it is, why you should do it, and how mashing at different temperatures affects your wort.
Step mashing was developed when malts were less modified than they are today. You might wonder why you should learn about the process and science behind it. The answer is simple: it’s a great technique for producing a wider variety of distinctive beers.
First, let’s look at malting.
Malting is the process of steeping, germinating, and drying grain to convert it into malt. During malting, glucans and proteins in the grains break down, making it easier for brewers to extract sugars. By performing rests at various temperatures, brewers can achieve some of this modification during the mash, resulting in increased sugar extraction and efficiency.
Nowadays, most homebrewers don’t follow a step mash schedule because malts are already well modified. The general consensus is that step mashing won’t significantly increase conversion. However, there are other reasons why you might want to perform a step mash.
How does mashing at different temperatures affect wort?
Specific temperatures are believed to be key in breaking down beta-glucans (gummy parts in the cell wall of barley), lowering the pH of the mash, and breaking down proteins. Enzymes play a crucial role in this process.
An enzyme is a protein with a specific structure that accelerates the breakdown of different substances called substrates. Enzymes speed up chemical reactions without undergoing any permanent change themselves. This means that enzymes are not “used up” in the reaction.
Brewers are interested in the optimal temperatures for these enzymes. The optimal temperature is the range in which enzymes perform most efficiently.
This range generally extends up to the temperature at which the enzyme starts denaturing. It’s important to note that enzymes don’t suddenly stop working when reaching this temperature; denaturation takes some time. Therefore, moving from one temperature step to the next doesn’t mean that you have stopped one enzyme from working in favor of another.
Which temperature steps should we be interested in?
35-45°C (95-113°F) | The Acid Rest
The acid rest is a step designed to lower the pH of the mash, making it more acidic.
In this temperature range, the acid rest can also break down beta-glucans, which is particularly useful when using a high proportion of wheat or oat malts. Phytase enzymes actively break down phytin molecules at this temperature, releasing phytic acid and lowering the mash pH.
Most of the phytase present is destroyed during the malting process due to the heat used, so an acid rest only works with lightly kilned malts. It takes at least an hour to see a significant change in mash pH during the acid rest. That’s why it is not widely utilized today, except for its effects on beta-glucan breakdown rather than mash pH.
43-45°C (109-113°F) | Ferulic Acid Rest
In beer, ferulic acid is a precursor to a molecule called 4-vinyl-guaiacol, which gives beer a desirable clove-like aroma in certain styles. Performing a rest in this temperature range releases more ferulic acid into the wort, providing more of the precursor to 4-vinyl-guaiacol.
44-59°C (113-128°F) | The Protein Rest
If your wort has an excessive amount of long-chain proteins, it may result in protein haze and instability when storing the beer. On the other hand, you need medium-chain proteins for head retention and body in the finished beer.
This rest helps break down protein chains into shorter ones, but it’s best avoided unless you’re using malt with high protein content. Most well-modified malts don’t require a rest at this temperature and it can negatively affect head retention.
61-71°C (142-162°F) | The Saccharification Rest
As the primary rest for brewers, many homebrewers utilize a single extended rest (60 minutes) within this temperature range. The purpose of the saccharification rest is to convert starches into sugars. Two important enzymes are involved: alpha-amylase and beta-amylase.
Alpha-amylase is most active around 68-72°C (155-162°F). It breaks starch molecules randomly, creating long chains that result in a sweeter, fuller-bodied beer.
Beta-amylase, on the other hand, is most active from 60-63°C (140-145°F) and breaks starch molecules at their branches, creating shorter chains. This is ideal for producing highly fermentable worts for drier finished beers.
If you’re new to brewing and want to expand your knowledge, explore our other articles. Feel free to contact us at info@ace-chn.com if you have any questions. We’re here to help!
