Author Topic: Does boil rate matter?  (Read 45 times)

Offline scottdj

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Does boil rate matter?
« on: Today at 02:47:04 PM »
When i do my boil, most of the time i'm doing it on my gas range - which has a limited BTU output.  It works ok, it just takes a while.  Sometime's i'll go outside and use a blichmann burner - which obviously has a MUCH higher BTU output - and as such, the boil time (time to reach temp, recover to temp after ingredients are added, etc) is far shorter than when i do it on my range.

My question is - does the energy input (and hence the boil duration) - matter?  If so, why, and what specifically is going on in a lower energy boil (longer boil) vs a higher energy (shorter) boil?


Offline denny

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Re: Does boil rate matter?
« Reply #1 on: Today at 02:58:00 PM »
Technically, you're probably better off with a low boil than a high one.  Practically, I don't think it makes a lot of difference.
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Offline Robert

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Re: Does boil rate matter?
« Reply #2 on: Today at 03:37:44 PM »
It isn't so much time as thermal loading; picture it as the area under a time/temperature curve. 

With an all-grain wort it can make a real difference.  There you want a short, low-intensity boil with less than 10% total evaporation (a good indicator,)  just enough circulation to achieve a good break and hop utilization.   More thermal stress will lead to effects such as the excessive breakdown of proteins and other substances resulting in a much duller, less fresh malt flavor,  the development of off flavors,  reduced capacity for producing and holding foam, and more rapid staling of the beer. 

But Denny's absolutely right at least as regards an extract wort.  Most of that damage has potentially already been done in the production of the extract, so you won't make a lot of difference either way.   That said, extract doesn't need any more boiling than your hop schedule requires because there's not much of a break to achieve, so no need to use extra fuel; do whatever is most efficient if that's a concern, or whatever is most convenient .
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Offline mabrungard

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Re: Does boil rate matter?
« Reply #3 on: Today at 03:53:09 PM »
While researching that presentation on Wort Boiling, I came across an Institute of Brewing and Distilling journal article that stated that they produced beer via a boil with only 2% evaporation loss. They said it tasted fine. Since they didn't identify what malts they used, I'm less confident that brewers can actually get by with that little evaporation. Most pro's that produce good products apparently evaporate about 4% to 8%.

I'm trying to limit my loss to about 8% and I do brew some beers with high pils malt content. The main thing that brewers need to concentrate on is the circulation of wort within their kettle. You actually don't want the kettle centered on your burner. Having the burner offset slightly to one side of the kettle will help promote a better rolling action for the wort.

A volcanic boil is not necessary. If there is ANY evidence that the wort is boiling, its as hot as its going to get and all the chemical reactions that we rely on will occur at the same rate. But you probably do need some heat input in order to produce the rolling action.
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