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Here's an introduction to partial mash brewing; a combination
of the introductions from Brian Kanuth's 'Mastering Homebrew' and Dave
Miller's 'Brewing the World's Great Beers'.
Partial mash brewing is a bit like using speciality grains - you use
some grain, and some extract in your recipe, instead of only using extract.
It is also like all grain brewing except that you don't need any extra
equipment as you are only handling 1-2 kg of grain.
However, unlike simply using speciality grains (which only contribute
small differences in flavour and colour to your brew), partial mash brewing
allows you to use grain to contribute to a significant portion of your
brew's makeup. This gives you far greater control over flavour and colour.
It also allows you to utilise the chemical properties of certain grains,
giving you greater control over characteristics such as mouthfeel, head
retention and body.
Partial mash brewing is simply:
- Soak (mash) your grains in hot water;
- Strain the water into your brewpot;
- Rinse (sparge) the grains with some more (hotter) water;
- Brew as normal (top up with water, add your extract, boil, add hops,
cool, aerate, pitch).
Besides your usual brew pot, you'll also need :
- a largish pot in which to boil your grains up
- something in which to hold a couple of litres of preheated water
- an accurate thermometer capable of reading temps up to the high 70s
(° C)
- some kind of strainer (such as a stainless steel colander) that will
fit over your brewpot.
If you don't already have one, a brew pot capable of doing a full wort
boil is essential.
- Get your usual brew gear together – sanitised fermenter/spoons/jugs,
yeast starter, malt extracts softened in hot water, etc. Your grain
should be cracked - use your own mill, use your brew shop's mill, get
your brew shop to do it for you, or just buy pre-cracked grain.
- Heat some water in your largish pot (let's call it a 'mash tun') to
70° C -ideally use 1.35 litres of water
per half kilogram of grain (that’s about 1 1/3 quarts of mash water
for every pound of grain).
- Add your grains (loose, or in a muslin or special grain bag) to the
mash tun and stir gently. Keep the water at 65-70°
C. Leave the grain to sit for 45 minutes. This will convert all the
starches in the grain to sugar.
- While your grain is mashing, heat some 'sparge' water (which you'll
use to rinse the grains) to 76-77° C.
It's pretty important that it stay at this temperature. Again, use a
generous 1.35 litres per half kilo of grain.
- Put the strainer over your brewpot and upend your largish pot into
it. The wort will collect in your brew pot, and the grains should stay
in the strainer. The wort will be cloudy.
- (Optional step) You can remove the strainer and pour the cloudy wort
back into the mash tun. Then put the strainer back on your brew pot
and slowly run the wort back through the grains a second time to filter
out some of the 'stuff' suspended in it if you like (Kanuth doesn't
mention recirculating in his partial mash intro, but Miller does).
- Leave the strainer full of grains over your brew pot. Get the sparge
water (make sure it's still at 76-77°
C), and slowly and gently pour it over your grains in the strainer.
This will rinse off any sugars that may still be clinging to the grains.
Do it a litre at a time, sprinkling over the whole surface of the grains.
When one litre has disappeared below the surface of the grains, add
another litre.
- Collect all the sparge water in the brew pot so it mixes with the
wort.
- Remove any husks floating in your brewpot. Top up your brew pot with
water, and proceed with the rest of your recipe (adding extract and
hops, boiling, cooling, aerating and pitching).
In summary:
- Heat 1.35 litres of water per half kilo of grain to 70°
C and chuck in your grain
- Leave it for 45 minutes to convert the starches to sugar (mashing)
- Tip the whole lot through a strainer into your brew pot (strain it
through the grain bed a second time if you like)
- Slowly rinse the grains with 1.35 litres of 76-77°
C water per half kilo of grain, collecting the runoff in the brewpot
(sparging)
- Top up with water and continue as per an extract brew
Cheers,
Matthew Tolley
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