Saturday, 4 December 2010

The Monster Mash

He did the mash
He did the monster mash
He did the mash...

Well actually a brewer does the 'mash' most days. The degree to which it's a monster depends on many a thing.

Mashing in is the first stage in the brewing process. It's where we blend the ready mixed malted barley and other grains (now called grist) and hot water (we call it liquor) to make a porridgey mixture. This steamy 'mash' is a sweet, satisfying smell close to heaven, particularly on a snowy -6 °C day in Sheffield. When we mash the grist with hot liquor, it has to be at the correct temperature for all the sugars to be released from the grain. This is the basic food for yeast, alcohol being the product of the sugar fermentation. Soaking the grains in hot liquor also releases proteins which make a lot of the beer flavour. After the mash has stood for a little while, we start to run off the liquor with everything dissolved in it - this is called wort, which is turned into our lovely beer.

For the geeks amongst you, the temperature must be 62 - 65°C to activate the right amylase enzyme. This enzyme breaks down the starch stored in the malted barley into fermentable sugar substrates for the yeast. Ideally we need lots of the disaccharide maltose which is produced from the amylase enzymes breaking down amylose. This maltose is fermented by yeast to produce Carbon dioxide and ethanol:

Maltose + Nitrogen (amino acids) + O2 + vitamins and inorganic mols → New yeast cells + ethanol + CO2

So that's the process and science, now for the monster.

Mashing in is done by eye - its where the art and experience come into it. It's important to 'mash in' at the right consistency so that we can get the best possible extract. The rate of hydration (liquor addition) is controlled by a valve which is adjusted by hand. This is important, as a brewer must keep the correct and uniformed consistency when the grist is released from the hopper into the mash tun. Unfortunately, when mashing in during the cold weather all you can see is lots of hot steam and no mash which only leads to what feels like burning your face off, and sneezing like mad. This is an unpleasant, awkward and mildly monsterish characteristic. As my head brewer always says, you've got to use your spider senses and trust your intuition to get it right.

The real monster is the mash tun. This is the big tub which we pour the mash into and leave it to stand, and in a micro brewery we have to dig it out by hand. For a 20 barrel brew (36 gallons per barrel, therefore 720 gallons) it's about 400kg of dry malt, so the weight of spent grains is much more. These spent grains have to be shovelled out of a little door, so a 30 barrel brew length, which is the biggest batch we brew at Kelham, is a bit of a monster to dig.

And it's blinkin' hot. That's another monstery characteristic.

So what happens to the spent grains? It's an awful lot of malt which we can't use again, so a farmer comes to pick it up in big tubs and his cows enjoy it for their dinner. Lovely.

The mash is a bit of monster, but I love it really and without it, there would be no beer.

1 comment:

  1. Cool article. All that chemistry to provide substrate for our friends the yeast.