Removing hops during the boil?

[Matt]

This is all a bit academic because the f'n wort is already chilling, but anyways:

Let's say you chuck in what you think is 20 AAU or so of 4.5% alpha hops for a 60 minute boil. After fifteen minutes or so, you realise that they're actually 7.8% alpha, and your wort is on its way to being massively overbittered.

You quickly run the calcs and realise that the 20 mins they've been in there is enough to extract the 20 AAU you were after. If you removed the hops at this point (say you were using a sock for pellets), then boiled for the remaining 40 minutes to get your evap loss / target OG, would the IBU outcome be the same?

 

[peas_and_corn]

You could either stop boiling and accept a slightly lower abv or boil til the end and accept a higher ibu level. Who cares, it's not like you must absolutely hit a flavour profile

 

[Droopy Brew]

I believe the hop oils are already in solution so will continue to add bitterness once the vegetable matter is removed. Ferment, taste and see what happens.

Or

Add some fermentables (malt extract, dex or belgian candy) boiled in a couple of litres to up the ABV and balance it out. Do at day 3 to 5 depending on the rate of fermentation ( aim to add at 1.025 gravity).

 

[ebyelyakov]

Your logic is perfectly fine.

Hops utilisation (just for academic purposes, lets assume the gravity is 1.05) at 20 minutes boiling is 0.144 versus 0.231 @60 minutes..

For 20 AAU you'd need 4.4 gms of 4.5% hops or 2.56 gms of 7.8%

Assuming your volume was 1 lt, the amount of IBUs will be:

1) 4.4g of 4.5% hops at 60 minutes = (20AAU*0.231*10)/1 = 46.2 (slightly higher than Pilsner Urquell)
2) 4.4g of 7.8% hops at 20 minutes = (34.32AAU*0.144*10)/1 = 49 (not a killer, provided you removed the hops after 20 minutes)

boiling 7.8% hops for 60 minutes would pump the IBU to almost 80, way to high.... Provided the gravity of the boil was 1.05, you relative bitterness ratio will be 1.67 -- way-way tooooo bitter.....

the formula for IBUs = (Weight*H%*U*10)/Volume...

Hops utilisation charts -- easy to google.... See the article from G. Tinseth

 

[manticle]

Basically - no.
Either shorten the boil and accept lower grav/higher volume, or keep going and get more bitter wort.

Following that, you can deal with it and learn for next time or blend with another beer.

 

[Danscraftbeer]

Or you might just like it more bitter. Just left them in and not worry too much.

The first non kit brew I made before any software. It was awesome, but bitter, but awesome.
A 60-25-2 minute addition of Sarochi Ace pellets.
Then plugged in the notes of that into the software it works out to be 53+IBU. !? :drinks:

 

[Matt]

OK, now I'm confused.

If I boil, say, 25g of 7.8% Northern Brewer for 20 minutes in what will be 15 litres of 1.045 wort (say the boil size is 17.6L if it matters), it'll be 20 IBU (if I believe Brewtoad). I guess it'd also have a fair amount of flavour, because it's in the ball park of a 15 min addition, but probably not as much aroma as, say, a 5 minute addition.

You seem to be saying that if I keep boiling for up to an hour, even if I've removed the hops, the wort will get more bitter. Is this because the hop oils are extracted by the boiling wort quickly, but are only isomerised proportional to the length of the boil? That is, the full potential bitterness of those 25g of hops is already in the wort, and the longer I boil, the more bitter the wort becomes, even though the hops themselves are gone?

 

[manticle]

Yep.

 

[manticle]

Hop utilisation is complex chemistry. You will not know what you actually get from your hops without spectroscopt or similar but simply fishing out the remnants won't stop further bittering.

 

[Danscraftbeer]

and, Relax. Its home brew.
Don't stress the figures too much. Its more method in my opinion so fiddling and handling brew is to be minimized.
Go with what it is.Trying to fix an imperfection could cause an imperfection or an Infection etc.
and waste not!. Oh you put a little too much hops in then oh well. Go with it and don't mess with it.

 

[Matt]

It's in the fermenter - we'll see how it goes in a couple of weeks. I'm a RDWHAHB cultist, so I'm not worried, but still nice to know what my options are when things hit the fan. Stopping the boil at 20 mins and getting 17L at 1.040 vs 15L at 1.045 would've been the best choice in hindsight.

Another question if that's OK: why do we leave hops in for the length of the boil at all then? Is it because traditionally it's been a case of 'chuck 'em in at the start, fish 'em out at the end', but in reality we could put them in there, get the oils into the wort, pull the hops out completely then let those oils isomerise? I mean, I don't know -why- you'd want to do that, but it's theoretically doable?

 

[manticle]

Leave them in because there's no real purpose pulling them out. Might as well try and do a light beer by removing the malt halfway in.

 

[Danscraftbeer]

Simplicity of method.
Howdya reckon the monks did it in the first discoveries of this.
Any and every way any of us could conjure up with what we have and waste not! :drinks:

 

[manticle]

Beer predates christianity, let alone monks. Wouldn't rely on all that old beer tasting same as you imagine yours when it's at its peak though.

 

[Matt]

Thanks all. Fifteen years in this hobby and I'm still learning stuff. I'll let you know how it turns out.

 

[yankinoz]

OK, now I'm confused.

If I boil, say, 25g of 7.8% Northern Brewer for 20 minutes in what will be 15 litres of 1.045 wort (say the boil size is 17.6L if it matters), it'll be 20 IBU (if I believe Brewtoad). I guess it'd also have a fair amount of flavour, because it's in the ball park of a 15 min addition, but probably not as much aroma as, say, a 5 minute addition.

You seem to be saying that if I keep boiling for up to an hour, even if I've removed the hops, the wort will get more bitter. Is this because the hop oils are extracted by the boiling wort quickly, but are only isomerised proportional to the length of the boil? That is, the full potential bitterness of those 25g of hops is already in the wort, and the longer I boil, the more bitter the wort becomes, even though the hops themselves are gone?

Yes, but to be picky, it's because the alpha acids go on isomerising.

 

[Danscraftbeer]

Beer predates christianity, let alone monks. Wouldn't rely on all that old beer tasting same as you imagine yours when it's at its peak though.

haa, Yeah I'd wonder about the old days beer.
and actually I meant the discovery of Hops as an ingredient for beer that I understand was first done by Monks? another story though.