homebrewandbeer.com

OK, I know that you should boil ya hops in some malt extract to get better utilisation. But how come beersmith gives a better AA reading when you boil them alone? Does the malt only help with the flavour & aroma side of things?

Bringing in hop utilisation into the equation would take a fair bit of maths and programming. So the basic principal is the malt is sweet, so on the program when you add more malt it brings down the IBUs. The AA shouldn't change on the program no matter what you do, unless you change it yourself before hand.

Hop utilisation is directly proportional to the gravity of the boil. The more sugars are already dissolved into the water, the harder it is to isomerise (and thus dissolve) the alpha acids from the hops. So you are right, you will get the best utilisation in plain water. However, there is a general view that the hops actually react with the malt in some way during the boil, "keying" in the bitterness to the hops. So your best compromise is pretty much to boil at a similar gravity to your fermentation gravity.

It is also best to boil as much of the malt as possible with the hops. This gives for a more homogenious bitterness in the batch.

The AA shouldn't change on the program no matter what you do, unless you change it yourself before hand.

Sorry I meant IBU