I'm having my first AG brewday tomorrow. It's GW exmoor gold clone. In the recipe it says to mash and boil for 90 mins - will it make much difference if I mash and boil for an hour? Many thanks in advance for your expert opinions.
Here is a take on 90m vs 60m for mashing:
The 90mins guide would probably be more relevant to a mash tun made from a Large Picnic basket sort of an arrangement, in which you add the grain to the water and dough them in. It would total 90mins, for this stage, from chucking them in (conjecture?).
Suppose you have an All-in-one system - for example a Grainfather, or if you waited a bit until the prices cam down, a Robobrew/Ace/Whatever RIMS.
In these systems you add the grain slowly, stirring every addition carefully and giving it a good stir at the end of this, with a view to driving out the air caught between the crushed grains. Them. half way through the mash, you stop the clock and unravel the kit a bit, give the grains a stir to drive out some more gases and re-assemble to proceed. Total time on the mash stage is not going to be far short of 90mins, since it is 20 mins doughing in and 2x5mins just stirring, plus the 2x30min periods when the recirculation pump is on and clearly operating.
As regards boiling, I have fewer transparent ideas, but would suggest that:
Cheap high Alpha "Bittering" hops make the necessity of a long boil somewhat irrelevant, and
Concentrating or caramelising the wort can now be addressed in different ways - larger and better, more efficient mashing systems and the availability of malts of graduated colouration.