EBU (European Bitterness Units) determine the bitterness of a beer. To calculate the weight of hops required to produce a beer with a certain EBU, the following formula is used:
Weight (g) = EBU x Volume (litres)
Alpha Acid x 2
For example, to brew a beer of 23 litres with an EBU of 30 using hops with an alpha acid of 7%:
30 x 23 = 460 = 32.86 therefore 33g of hops are used
7 x 2 14
Alpha acids vary from hops to hops. If you obtain the same type of hops and the alpha acid changes, the following formula is used to re-calculate the new weight of hops required.
New weight (g) = original weight x alpha acid of original hop
new alpha acid of hops
e.g., 30g of hops with an alpha acid of 6.5% were previously used. The new alpha acid is now 7%:
30 x 6.5 = 27.86 therefore 28g of hops are now required
To calculate the ABV (Alcohol By Volume) of a beer, the following formula is used:
ABV = original gravity – final gravity
For example, if the original gravity is 1040 and the final gravity is 1010:
1040 – 1010 = 30 = 4.02 therefore the ABV is 4.0%
Working with Tempertures
When using the full mash process, the ideal strike heat temperature is from 73˚C to 76˚C. Once the water has mixed in with all the malt grist, the mash temperature should be approximately 66˚C. However a mash temperature between 64˚C and 69˚C will still produce good results.
When sparging, a temperature of 78˚C is ideal for rinsing out sugars from the malts.
A rolling boil of 90 minutes is necessary to allow proteins to be removed thus allowing clearer beer.
Once the boil is complete, the wort is cooled down to around 20˚C before pitching in the yeast.