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PostPosted: Wed Apr 28, 2010 8:19 am 
Just wondering why a boil time of 90 mins is recommended even though the first hop addition might not be until 60 min? :? Is it to do with getting rid of DMS? I'm planning to do a Brown Porter, in which case I would guess that DMS wouldn't be such an issue?


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PostPosted: Thu Apr 29, 2010 5:06 am 
Some beers will do better with a longer boil time and some with less. The 90 minute boil is a very safe boil time for most beer styles. Any less and you can start to get clarity problems etc. Any longer, for most beers, is a waste of energy.

When to add boiling hops is another area open to debate. 60 minutes is a convenient time as the boil has got rid of a few nasties by this stage and it also gives the brewer a chance to weigh out all their hops in the first half hour of the boil. Some people prefer adding bittering hops right at the beginning. I tend to do mine at 75 minutes or 60. I think most brewers would be hard pressed to tell the difference between bittering hops added at 90 and those added at 60. Which one tastes better would be very subjective as well.

Cheers,
PP

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PostPosted: Thu Apr 29, 2010 6:41 am 
Convention mostly, I think, a 90 minute boil is the safe option for most beer types however most recipes' hops schedule revolve atound 60 minute additions. To extract the maximium bittering potential out of a limited amount of hops, it can be boiled for longer, but the bettering increase between 60 and 90 is not great. Some brewers swear by a 60 minute boil though and are adding the bittering addition as soon as the boil starts.
However, some caramelisation of sugars takes place with a longer boil, that's what I'm after when I make my house Landlord-ish ESB, but I'll often caramelise a couple of litres of wort (boil it down almost to toffee) as well for some emphasis. I did try a 120 minute boil with one recently and the wort clarity was quite remarkable (sorry Pat, no photos... :cry: ), I'll see if that translates to clearer beer when it is finally bottled. For me personally though, clarity is only a by- product as great tasting beer is what I want, I don't really care what it looks like, just pleasing when it is clear.
IIRC, someone out on the interwebs mentioned that adding hops after the boil has started and progressed a little is beneficial to bittering, in what way I can't recall. A "First Wort Hops" (FWH) addition though is the other end of the scale, where hops are added to the wort as it is drained from the mash tun and swear by it for better bittering. So, it appears that YMMV...
DMS shouldn't be an issue with a porter, particularly is you're using just ale malt, the only time I've encountered it is with very pale pilsner malt.
IBD takes a detailed look at functions of wort boiling, it is a thoroughly good read and quite a lot of technical detail.

Hope this helps!

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PostPosted: Thu Apr 29, 2010 9:23 am 
I always do a 90 minute boil for lagers and 'cream ale' type brews. However I'm tending back to doing a 60 minute boil for ales nowadays. I've been doing some checking around UK breweries websites and many of them are quite open about what methods they use, for example the series of short videos on the Wychwood (Brakspear) site ,and 60 minutes seems to be common. Can't argue with that. I now do a bit longer than an hour, I give the boil about 5 minutes to clear the gunge off the top and get a bit of break happening, then put in the bittering addition and count 60 minutes from there.


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PostPosted: Thu Apr 29, 2010 9:39 am 
Ralph wrote:
So, it appears that YMMV...


Huh? :?


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PostPosted: Thu Apr 29, 2010 9:40 am 
Ralph wrote:
IBD takes a detailed look at functions of wort boiling, it is a thoroughly good read and quite a lot of technical detail.

Hope this helps!


Thanks for the link Ralph. Will give me something to read on the train tonight.


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PostPosted: Thu Apr 29, 2010 3:11 pm 
YMMV= your mileage may vary! Maybe not the most appropriate expression in this case, I guess I mean there's varying opinions, but also various effects that brewers are after too.

(Getting a bit OT here) BTW, you like the Wychwood vids too, hey Beachbum? Thought you might! I was intrigued by the machine that seemed to be a densitometer, need to go back and check that out (just under half way through the fermentation one, in the lab).

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PostPosted: Thu Apr 29, 2010 5:53 pm 
OT: The machine in the Wychwood fermentation video is probably an older model Anton Paar density meter, their website is pretty crap though...

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PostPosted: Fri Apr 30, 2010 8:29 am 
OK. So after reading the responses to my original post (thanks everyone) and the IGB info Ralph posted, I have made a few conclusions.
1. Lagers need longer boils than ales (depending on base malt used), mainly to get rid of DMS.
2. Longer boil times may aid with clarity.
3. Boiling hops for longer than 60 mins will start to reduce bitterness.
So I'm gonna try Beachbum's suggestion of 60 min for ales and 90 mins for lagers but with first hop additions at 60 mins.
Thanks all :D


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PostPosted: Fri Apr 30, 2010 7:42 pm 
Hi again Aaron,
sounds fair, except one vital aspect. Bitterness will only increase with longer boiling beyond 60 minutes, albeit at a reduced rate. Try fiddling with the addition time of a fixed amount of hops in a brewing software package, you'll see that the level of bittering, as far as I'm aware, will only go up with with a longer boil but the rate of increase drops off pretty significantly after an hour. Once bittering compounds are isomerised (basically dissolved), they're isomerised and there's no turning back. At least that's how I think it works...

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PostPosted: Sun May 02, 2010 6:14 am 
AaronP wrote:
OK. So after reading the responses to my original post (thanks everyone) and the IGB info Ralph posted, I have made a few conclusions.
1. Lagers need longer boils than ales (depending on base malt used), mainly to get rid of DMS.
2. Longer boil times may aid with clarity.
3. Boiling hops for longer than 60 mins will start to reduce bitterness.
So I'm gonna try Beachbum's suggestion of 60 min for ales and 90 mins for lagers but with first hop additions at 60 mins.
Thanks all :D


Nup, we have a problem here.

Some lagers actually need short boils so as the colour remains light. Long boils stuff this up.

The main thing to remember is that a 90 minute boil is the one that is most likely to serve you well.

It is doubtful that any new brewer (lager or ale) would have a good reason for varying from BB's 90 minute recommendation. Stay with it if in doubt.

Cheers,
PP

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PostPosted: Sun May 02, 2010 7:39 pm 
Bugger! I should have known better than to think it would be that simple.
You're right PP, The only reason I want to reduce the boil length is because I only have a 15L pot and want to minimise how much volume I lose to evaporation.


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PostPosted: Sun May 02, 2010 8:36 pm 
G'day Aaron - any reason why you can't boil some water in the kettle and add a bit of hot water during the boil? I do this with every batch I make because I am doing 25L batches in a 30L urn (for what it's worth, I always do a 90 minute boil - can't really say why, just that it's conventional and I am trying to get a consistent process before I consider changing something like this).


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PostPosted: Sun May 02, 2010 9:24 pm 
dick wrote:
(for what it's worth, I always do a 90 minute boil - can't really say why, just that it's conventional and I am trying to get a consistent process before I consider changing something like this).


For what it's worth (nothing) I most always do a 60 minute boil. I drink beer while I watch the bubbles float skyward. That extra half hour drinking causes me too many mistakes. I forget the Irish moss or last hops. Yesterday I did two batches. I would never have made that last 90 minute boil!

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PostPosted: Mon May 03, 2010 8:20 am 
dick wrote:
G'day Aaron - any reason why you can't boil some water in the kettle and add a bit of hot water during the boil? I do this with every batch I make because I am doing 25 L batches in a 30 L urn (for what it's worth, I always do a 90 minute boil - can't really say why, just that it's conventional and I am trying to get a consistent process before I consider changing something like this).

Quite right dick, yep, you sure can add more water, although it is better for efficiency if you've sparged with it first! :D
Seriously, I actually do both- I'll often add sparge and also just straight boiling water to my piddly kettle (a big double ewe 19 L stockpot). Because I usually do over- gravity boils and dilute prior to pitching, the actual post- boil SG is not really that important as it will be changed later anyway, in the beginning I figured I may as well have the pot as full as possible all the time to help with hops utilisation (see below).
Dunk sparging is one way to do this, it uses the additional water to extract more of the remaining sugars out of the mash, the actual numbers are not huge, equate maybe to 3 L of additional full- strength beer (eg. yesterday yielded 5 L * 1.034 of sparge from 4 kg of grain), but when the volumes are fairly small anyway, this becomes significant and can be even more helpful in offsetting trub and fermentation losses.

Aaron, if you are squeezed for kettle volume, perhaps you should do an over- gravity boil and incorporate a dunk sparge/ mashout step after mashing, I do this most of the time as I use just a 19 L stockpot as my kettle for 23 L batches (I am also putting together a guide for this very method). After getting the first runnings in your kettle/ pot and putting it on the stove, just drop the bag of grain into another bucket or pot and add about 1 L - 2 L of water (just off the boil) per 1 kg of grain, stir thoroughly, let it sit for 10 minutes, then lift & drain as before. This gives you more liquor to add to the boil to replace evaporation losses but also harvests more sugars left in the grain after the first lift. Always use hot water for this BTW, never use cold or it will end up adding nasty- tasting tannins, also it helps if the water is slightly acidified with a pinch of citric acid (not essential though).
Suggest also if you do the dunk sparge to reduce the mashing water rate to around 4 L per 1 kg of grain or there may be just too much liquor. That's a fairly thick mash for a BIAB though, but you should be able to squeeze 3 kg of grain into that pot, maybe even 4 kg and still get reasonable efficiency.

As mentioned, if you're not sparging but have a concentrated boil then adding boiling water is fine to make up for evaporation losses, obviously if you add too much though you'll dilute it below the desired specific gravity (i.e. Original Gravity at the start of fermentation). This will require additional boiling to evaporate but keep in mind that this will also increase the bitterness if any hops have been added at that point. If you add cool water, the boil will halt, in which case you should pause your boil timer until it comes back up to the boil, so only add boiling water if you want to avoid that. A domestic kettle is handy for this.

One other thing to remember in over- gravity boils is that hops utilisation begins to drop off with wort of over 1.050. It is easily adjusted for though, I estimate about 10% more hops per 10 gravity points (i.e. 1.060 is 10 gravity points over 1.050). The human palette is going to struggle in picking up this difference though, so I wouldn't be overly concerned if your boil is creeping over 1.050. Also, when adding adjunct sugars, add them right at the end, which will help with hops utilisation efficiency during the boil.

Happy to discuss! :cool:

Ps. Sorry for all the odd- looking numbers and units, just seeing if the unit converter works properly!

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PostPosted: Mon May 03, 2010 7:38 pm 
I had considered doing a dunk-sparge and adding that sweet liquor but was hesitant because I wouldn't be able to predict my OG. Maybe a high-gravity boil is the way to go.


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PostPosted: Mon May 03, 2010 8:48 pm 
Yep, the beauty of the dunk sparge/ high- gravity boil is that you can dilute it to exactly where you want it for OG rather then just accepting what you get with other methods. (I am about to do this tonight with 16L of 1.074 3% Caraaroma Landlord, should give me about 24L of 1.050). The maths are roughly:
Actual SG/ Target SG * Actual Volume
(SG such as 1.050 expressed as 50, so 74/50*16=23.7, so, after rounding, water added= 24-16=8L)

The down side is that the final volume may not be quite what you are expecting plus you may have to adjust for hops utilisation. IMO, this flexibility is worthwhile if you are limited for kettle volume.

The other side of the coin is to work out how much your boil SG will change by adding sparge liquor (measure both- takes time) and if it can be evaporated back to where you want it, for small sparge volumes this is generally no hassle.

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