Partial Mashing, Mini Mashing & Cereal Mashing Decoded

One of the most fundamental events of brewing beer is adding water to grains… and even though this event can take on many different names, you only need to worry about answering these two questions: Are you converting starches into sugar and then extracting that sugar? or are you just extracting sugar from grains?

When you are able to answer these two questions, then it doesn’t matter whether you call the event a mash, partial-mash, mini-mash, steeping, cereal mash… or whatever…

What needs to be understood here is what are your grains made up of… starches or sugars?…

So let’s talk about how these grains are made, the difference between them and how you will use them…

I break down the malting process into two steps… making the contents of the grain accessible (starches, proteins, etc.), and breaking down those contents into usable size components…

For the first step, maltsters wet the grains and what that does is to break down the cell wall of the grain so the contents become accessible…

Then the maltster begins to heat the grains which speeds up the process of breaking down starches and proteins into smaller sizes… in other words, starches start becoming dextrins, which are complex sugars and proteins are broken down to a size that won’t cause haze…

The difference between malts that need to mashed or steeped is that malts that have their starches broken down so much that they become sugars are the malts we use for steeping…

All the other malts are used for mashing… all the malts that eventhough may have had some starches broken down, they are still made up mostly of starches…

Now, in order to use these grains for partial mashing or mini mashing you need to understand one component of these malts…

When maltsters add water to grains to make its components accessible, they are also activating enzymes… think of enzymes as your workforce… the loggers that cut down starches and proteins into smaller sized components (sugars, and non-haze forming sized proteins)…

However, during the second stage of malting, some malts are heated with different moisture levels to produce flavors… depending on the moisture level and the temperature, some of these malts lose enzymes, which are needed to convert starch into sugars… these malts are usually known as High Temperature Kilned Malts…

When all grain brewers use these malts, they are relying on the enzymes from base malts (lager malt, pale ale malt, etc.) that haven’t been heated much during malting and therefore have plenty of enzymes, which can be used to break down the starches of other grains…

In other words, when grain comes into contact with water, the enzymes mix with the water and they work on any starch that is in contact with the same water…

This is how you are able to brew with adjuncts…

An adjunct is basically defined as any source of starch that does not have enzymes to convert itself into sugar… rice, corn, and oatmeal are some examples of starches that don’t have enzymes…

In order to convert the starches from these grains into sugar, what brewers do is add grains that have enzymes so that those same enzymes can work on the starches of both the malts and the adjuncts…

So now let’s talk about the difference between a partial mash/mini mash and a cereal mash…

First, why would you want to do a partial mash or mini mash… Well if you brew with extract, then a way to add different flavors to your beer is by using flavor malts… the most common malts used with extract brewing are caramel or crystal malts… these malts have already had their starches converted into sugar and have absolutely no enzymes… so when you add water to these grains, all that you are doing is extracting that sugar to add color and flavor to your beer…

But what if you want to get the flavor from high temperature kilned malts… malts that have that bready, malty or toasty flavor you don’t get from caramel or crystal malts?

Well, that’s where partial or mini mashing comes into play… you would basically steep these grains the same exact way you would steep caramel or crystal malts, with one exception… since some of these malts like Munich, and Vienna malt among others, have lost enzymes during the malting process, what you need to do is add a base malt that has enzymes so that the starches from high temperature kilned malt can be converted into sugar during the steeping process… and that’s why we call this partial or mini mashing instead of steeping…

If you don’t add a base malt then you may still get some of the flavor and partial conversion, but you won’t get the same results…

Munich and Vienna malts do have some enzymes, but the number of enzymes has been reduced and therefore conversion takes longer or is many times incomplete…

From a visual stand point… steeping and partial mashing are the same process… grains are sitting in hot water around 154 F, which is the temperature where enzymes that convert starch into sugar work the best…

The difference is in the type of grains that are in the water and what’s happening… grains that are made up of sugars and those that are made up of starches (and have enzymes)… anytime starch is being converted into sugar I like to use the word mash…

Now how does partial or mini mashing differ from cereal mashing?

Well, when you are brewing with adjuncts like rice or oatmeal… your concern is not just to convert their starches into sugar… you have to worry about first making the starches accessible…

Rice and oatmeal don’t go through the first step of malting, so what you do is cook them first… When you touch or bite uncooked rice, you can feel it’s hard to bite through the outer shell… when you cook it, however, it becomes really soft…. well just like you, the enzymes will have a hard time getting through the shell of uncooked rice, but once you cook it, the starches inside become accessible… the same goes for oatmeal, corn, flaked corn, and other similar adjuncts…

When you first cook an adjunct to make its starches more accessible and then add it to the main mash, you call that a cereal mash… also known as adjunct mash…

You’ll hear brewers use the words, steeping, partial or mini mashing interchangeably… so don’t be confused, by what they call the process… just understand the types of grains that they are using and if there is any conversion of starch into sugar going on at all…

Cheers!

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