90 Minute Boil Time and mash efficiency.

[battwave]

Really enjoyed talking to some of you guys at Matchfest. I took away two things: hotter mashes (thanks Prolix, 68C really delivered on body) and 90 minute boil times. On the latter, having spent over 10 years using 60 minute boils, I've done a couple of 90 minute boils, and I have to say I'm wondering if that extra half an hour on an already long brew day is delivering value, particularly where I'm using home-grown hops. Have any of you guys done comparisons?

Secondly, using the brew calculator (again something new to me), I seem to be getting around 65% mash efficiency. I'm using a 6 gal boiler with a false bottom and 4-5 litres of water per kilo of malt. Does this sound a reasonable efficiency?

All suggestions gratefully received.

 

[dennisking]

Think its been said on here before, commercial brewers brew for 90mins. Think how much money they would save if they cut it by a 1/3

 

[jamesb]

You boil to secure the hot break, which normally takes about an hour. Boiling after that only serves to isomerise more of the alpha acids in the hops. If you get a decent hot break after 60 minutes, just use more bittering hops to compensate if you don't want to do a 90 minute.

Some commercial brewers (not micros) brew for 45 minutes. They are boiling under pressure though which I believe secures the hot break faster. I suspect they're also using tetrahop extract so they don't need to worry about hop bitterness.

 

[battwave]

Thanks guys, that makes sense. Definitely always had the clearing effect of hot break (and a little help from irish moss) at 60. Immersion chiller definitely improved it further, so I can see that one with my eyes!

Did wonder if the 90 was going to give me more caramelisation, but the more I read, the more I think that seems to be a limited effect. Wife (chef half of chef & brewer) cites example of reducing onions, which don't start to caramelise until the water content is very low. Perhaps why some recipes seem to take a litre or so of pre-hopped wort off and reduce down?

I'll have a look on the topics on efficiency, but if you guys have any thoughts.....