Behind the Scenes: Mash Up!

We love having visitors to the brewery. We love showing them around, explaining how we make beer, telling them what everything does and having them experience the taste and aroma of our ingredients. In the past we have hosted everyone from school science classes to stag-dos. But at the moment, we just can’t do that and that’s a real shame. So, in these unprecedented times, we’re having to bring the magic of brewing to you in other ways, starting with this post.

It seems appropriate to start at the beginning, and when it comes to making beer, the first step is mashing-in. But what is mashing-in, what does it do and does it involve potatoes? (Spoiler alert: it doesn’t). At its most basic, mashing-in involves combining pre-crushed, malted grain with hot water to make a “mash”, a thick, porridge-like mixture. Despite what some people think, it’s not like mashing potatoes, there is no mechanical macerator that chops everything up; we just give the mixture a stir with a big stick and then leave it. But clearly there’s a bit more to it than that. This is the process by which the alchemy of turning the base ingredients of grain into beer happens. So what’s the deal?

Well, as I’m sure you know from secondary school science, to make alcohol, yeast needs to be able to ferment simple sugars. But grain - like barley and wheat - doesn’t contain simple sugars; it contains starch, which yeast can do nothing with. However, starch is like lots of sugar molecules all stuck together in a chain, so if you can chop up the starch, you get sugar and the yeast can get to work. Fortunately malted barley contains just the tools for the job - enzymes called amylases. These enzymes can happily get to work chopping up starch into sugars, but to do this they need just the right conditions. In particular they need to be wet and they need a temperature between 60-70C, but even the precise temperature has an effect. For example, if the mash temperature is around 60-65C, it tends to produce a drier and lighter beer, such as lager, whereas at 65-70C, it tends to result in a sweeter, more full-bodied beer, such as a rich ale. Part of the art of brewing is hitting just the right mash temperature for the beer that you want.


The type of malt you use in the mash also has a big impact. To make sure you get proper conversion of starch into sugars, you need plenty of those enzymes I mentioned earlier. Those enzymes are destroyed by the sort of cooking used to make darker malts, so even if you are making a stout or a porter, you still need lots of pale malts just to make sure you have enough enzymes to make the sugar you need. To make those darker beers, you just add in a little bit of dark malt for colour and flavour.

So, by mixing the right blend of malts with water at just the right temperature, we can start the process of turning starch into sugar, but this process takes time, so at Mad Cat Brewery we tend to leave it for around 90 minutes for the enzymes to do their magic. After that, we strain off the liquid, which is now full of lovely, sweet sugars, and called “wort”, whilst rinsing the malt with more hot water to remove any sugar left behind in a process called “sparging”.

“What comes next?” you ask, well, that will have to wait for another time. In the meantime, if all this talk has made you thirsty, why not head over to our online shop and see if one of our beers takes your fancy?