The 20 minute brewing system actually takes a couple of hours. The name refers to mashing and boiling times, which are traditionally one hour or longer. Shorter mashing time means a reduction in efficiency, so the grain bill is slightly increased, and a short boil usually means lower hop utilization, but first wort hopping (adding the hops to the kettle as the first runnings are going in) obviates this to some extent, and this style of beer (despite the name!) has a fairly low bitterness level compared to pale ale or IPA.
The time reduction is a nod to busy home brewers: we don’t stop brewing for lack of funds, space or even because we have access to excellent beer. We stop brewing because we just don’t have the time!
Part of the system that really helps in the time reduction is the use of very high-powered gas burners for heating the water and boiling the wort, pumps to move the hot/boiling liquid around, and a very high-efficiency heat exchanger to cool the wort rapidly. By putting all of these things together with a 20 minute mash/boil a reasonably nimble brewer can knock out an all-grain brew in less than 2-1/2 hours (including clean-up!), where traditional all-grain brews take six hours or more.
Two more things: first, to ensure that you’re getting conversion, it’s imperative that you do an starch test on your mash after 20 minutes, before you start sparging. This is done by putting a small amount (less than an ounce) of wort onto a white plate or white plastic lid and putting a few drops of iodine into it. Swirl the plate to mix: if the iodine shows purple and stays that way, there is starch present and you need to extend your mash. If it stays reddish-brown and disperses, the starch conversion is sufficient to proceed.
Second, batch sparging saves a lot of time. After vorlauf (recirculating wort through the mash bed to clear it of husks and grain) run off all of the wort in your mash vessel, add 100% of your spare water, stir, do vorlauf again and run off the rest of the wort. This will help increase efficiency a bit as well.
Makes one Firkin (41 litres, 9 Imperial/10.8 US gallons)
- 14 lbs (6.35 kilos) Maris Otter
- 1 lb (.45 kilo) 15L Crystal
OG 1.035, 3.5% ABV
Mash at 154° F (68° C) for 20 minutes
BOIL ADDITIONS & TIMES
2 oz. (28 grams) Kent Goldings First wort hop
Boil 20 minutes
2 oz (28 grams) Kent Goldings at flameout: whirlpool for 5 minutes
Use a highly flocculent British Ale strain. Imperial yeast A09 Pub or Safale S04. Do a ten-day primary fermentation and keg/bottle when it falls clear.
From The Cask 