The first step in the process of brewing beer is mashing. During this step, you will heat the grains in water, creating the basis of beer: wort.
Why do we have to mash?
For brewing beer we need a liquid containing sugars. This liquid is known as the wort. For making the wort we first have to make a mixture of grains and water. And this mixture is what we call the grist. But why do we need this and how does it work?
First of all it is good to know that the used grains contain starch. It is this starch that forms the main factor of the wort. However, starch alone isn’t enough. It requires the mash to be heated just because that will activate specific enzymes.
At this point the enzymes are the main actors in the mash. They will break down the starch into different sugars. Simply said you will end up in fermentable and non-fermentable sugars. Thus using a lower temperature will result in a high fermentable wort. And using a higher temperature on the other hand will give you a more non-fermentable wort.
Also good to keep in mind is that a higher fermentable wort will be dryer and probably give you a beer with a thinner mouthfeel. A sweeter beer with a thick moutfeel are the result of a high amount of non-fermentable sugars. To conclude we can say that the used mash steps (temperatures) will determine the style of beer you are brewing.
What about the enzymes?
There are two enzymes worth to mention: alpha-amylase and beta-amylase. The enzymes that should be activated during the mash depend on the beer style you are brewing. If you want a high fermentable beer, then beta-amylase is the enzyme to use. For a low fermentable beer, you have to focus on alpha-amylase. Of course, you can aim for something in the middle. It is all about seeking the balance and the beer you want to end with.
Beta-Amylase for Fermentable Sugars
In the beta-amylase phase, the starch is broken down into fermentable sugars. To activate the enzymes, you have to use a temperature between 61 and 66 degrees Celsius. The optimal mash temperature for beta-amylase is around 62 degrees Celsius.
The breakdown of starch occurs at the ends, but not on branches. Groups of two glucose units (maltose) are created. These “fermentable sugars” are the nutrient source for the yeast and will be completely converted into alcohol and carbon dioxide. Therefore, there will be no trace of them left in the beer.
The amount of alcohol you end with in the beer depends on the time the mash is heated. A longer time with beta-amylase result in the creation of more fermentable sugars, but this is not infinite. There is a certain point when there isn’t any starch left.
Alpha-Amylase for Non-Fermentable Sugars
If you are aiming for a sweeter and fuller beer, then you should active the alpha-amylase. During this phase, the starch is broken down into large pieces. To active the enzymes, you should heat the mash to a temperature between 71 and 73 degrees Celsius. 72 degrees Celsius is the optimal temperature.
The breakdown of starch occurs randomly, except on branches, creating larger pieces of glucose that are soluble and sweet. These pieces are called dextrins.
Due to their size, dextrins cannot be processed by the yeast. Because they cannot be processed, they are “non-fermentable sugars.” These sugars contribute to the sweetness and fullness (body) of the beer.
Mash-Out: Stops the Conversion Process
The enzymes will stop working at certain temperatures. This is because they have a range of temperatures where they are active, and temperatures above that range will deactivate them. This also means that dropping the temperature of the mash won’t reactivate them again. Thus, when the enzymes stop working, it’s permanent.
In most recipes, the mashing stops by performing a mash-out. In this step, you deactivate the enzymes to stop the conversion of the starch in the malt. In most cases, you can use a temperature of 78 degrees Celsius for this.
Crush the grains in preparation for the mash
Preparation is key. It always is. And so this is also the case when brewing beer. In order to use the grain you have to crush the grains first. This process involves milling the grist with a grain mill. The mill will break the husk and opens up the starch in the core of the grain. By opening the core the starch will become accessible for the enzymes.
Mashing in: Add your grains to the water
Once the crushing is done, you can start by adding the grist to a specific amount of water. This step is called “mashing in”. During this step, you add the grain bill in smaller amounts to the water. It is good to stir the grains well to prevent that any lumps are formed. After adding your grain bill, it’s time to gradually heat up the grist.
The grain bill and the amount of water that you have to use depends on the recipe you are brewing. You can imagine that a heavy beer ask for more grains than a light beer would.
It is also advisable to make sure that the temperature of the water is slightly higher than the temperature at which you are going to start mashing in. This is because the malt is a bit cooler, so the temperature will drop. Personally, I use a temperature of 66 degrees Celsius.
Different mash steps
During the mash you will heat the grist to different temperatures. First you heat up the grist to the temperature you need. If you reached the required warmth, than it time for a rest. Just keep the grist at the right heat for a given time. This is what we call a mash step. Each recipe consists of one or more steps.
If you want a dry and somewhat alcoholic beer, it is good to mash for a longer time at, for example, 62 degrees Celsius. If you want a fuller and sweeter beer, then it is better keep the grist for a longer time at 72 degrees Celsius.
But you can also combine it by choosing a single infusion mash. In this case, you aim for the middle. 64 degrees Celsius for a drier beer, 66 degrees Celsius for a not too dry but also not too full beer. If you want a fuller beer, go for 68 degrees Celsius.
The right grist thickness
Another important point is the thickness of the grist. The thickness refers to the ratio of grain to water during the mashing. It is all about the amount of water that is mixed with the grain bill, and this affects the consistency of the mash.
Ideally, a good ratio should be 4-4.5 liters of water per kilogram of grains. This means that we use 16 liters of water for a grain bill of 4 kilograms.
The enzymes can do their job better if the grist is a bit thinner. However, the mash efficiency can be negatively affected when the grist is too thick. This is usually the case with heavier beers, because the capacity does not allow for a thinner grist. An alternative is to brew a slightly smaller volume so that the grist can be thinner.
If the grist thickness becomes too thick, it might be impossible to stir. If that occurs, you can choose to mash in two stages. This is called a double mash and is also a possible solution if you have a capacity problem. Thus, if you want to use more grains than fits in the kettle.
Clearing and lautering: end with wort
When you’re done mashing, you’ll end up with a mixture that contains the desired fermentable and non-fermentable sugars, as well as non-desirable insoluble parts. These insoluble parts are no longer needed, and so the grist must be separated.
In principle, only the liquid or wort should remain. During the clearing and lautering step, the mash is filtered in a lauter tun, leaving the insoluble parts behind. The filtered mixture is what we call the wort, and the rest is the spent grain. With the spent grain you have two options: you can either throw it away or use it to make other things, such as bread.
Using the Brew in a Bag (BIAB) method
One way to bypass the filtering process is to use a brewing bag. In this bag, you put the crushed malt, and when the mash is completed, you pull the bag out of the brewing kettle. After draining, the wort remains. This method is also called the brew in a bag method (BIAB).
One of the advantages of the BIAB method is that it can be used with any size of brewing kettle. This makes it a popular method for home brewers who do not have access to large brewing systems or who prefer to brew smaller batches.
