Small Volume Extract Wort Boil

[wobbly]

I am trying to do small (15lt) full extract brews while travelling in a caravan and my ability to boil the hops is limited as I only having a 6lt capacity pot with me therefore boil size is limited to something about 5lt total (other wise major boil overs)
and I dont really want to do more than the one boil as that could result in a long day

My question is can I make say a 5lt wort at say 1045 and add my full compliment of hops to that for the boil and then add that to the fermenter along with the balance of the liquid malt extract and ferment the normal way

Cheers

Wobbly

 

[carniebrew]

Wobbly,

Yep, no problem with that, get your boil gravity around 1040 by adding about 1kg of LME (or 900gm of DME) to 10 litres of water. However, if you're doing smaller than around 8 litre boils, you'll need to up your hop additions marginally in order to get the same IBU as you would from a larger volume boil. It's something to do with the amount of hop goodness that can be extracted in such a small volume of boiling wort.

Using a partial volume boil calculator, such as the "Hop Concentration Factor" in Ianh's spreadsheet, shows that a brew with a hop schedule that would make 33 IBU in a 22 litre batch, will only make ~20 IBU in a 5 litre boil. You could guesstimate it yourself by adding say 50% more hops at each addition for your recipe, but you'd be better off getting a tool that will apply one of the popular formulas out there for you (Rager, Tinseth etc). If you're any good at Excel, try Ian's spreadsheet.

If not, then if you want to send me your recipe I'll put it through the tool and let you know what changes you could make. Just keep in mind that the formulas are just someone's calculation...you may find after your first 5l boil that it's too hoppy, or not enough...and can then adjust future recipes accordingly.

 

[stakka82]

I am trying to do small (15lt) full extract brews while travelling in a caravan

True brewing spirit!

 

[RelaxedBrewer]

If you want to calculate the exact amount of hops you need and don't mind a bit of maths. Palmer explains it pretty well in his book.
http://www.howtobrew.com/section1/chapter5-5.html
It is actually pretty simple once you get your head around it.

 

[wobbly]

RB

Thanks for the link to Palmer however my question/issue was not how to calculate the hop utilization for different strength worts but if I could do a small boil (5lt) with sufficient hops to bring the IBU up to where I wanted it for a 15lts into the fermenter and I think Carniebrews answer says that it will be OK but I might have to increase the hop additions

Cheers

Wobbly

 

[citizensnips]

You planning on fermenting while your caravan is on the move or you gonna be taking extending breaks and doing it then? either way respect for what your doing, sounds like your living the dream

 

[manticle]

Absolutely fine (many extract beers are made this way) but I would add the remainder of your malt about 5-10 minutes out from the end of the boil. Extra sanitation, helps dissolve, etc.

 

[wobbly]

Thanks for the advice but one point that I'm having a bit of difficulty getting my head around is why the advice seems to be that it is necessary to increase the hop amounts/weights to counter the smaller boil volume.

I understand why you need to increase hop weights as the SG increases. But if say "normal" range wort (1045 - 1050) will only absorb a certain amount of hops flavour/bitterness per volume how will adding an increased amount of hops get you closer to the target IBU once you add the additional LME and top up water to bring your brew up to final target volume.

Confused

Cheers

Wobbly

 

[rosshorne]

Utilization is the reason.

There are many things that factor into isomerization of hops (adding hop bitterness to wort). One of them is the gravity of the wort. The lower the gravity, the more bitterness.

"The gravity of the boil is significant because the higher the malt sugar content of a wort, the less room there is for isomerized alpha acids." http://www.howtobrew.com/section1/chapter5-4.html


I could be wrong or perhaps my reasoning is wrong, butI believe another is the amount of wort being boiled. More volume produces more room for isomerization and more convection or roll in the boil. This is part of the reason you a full boil gets better utilization then partial boils and why larger breweries get even better utilization.

My method for extract brewing (stolen from that amazing IanH Excel sheet) was to boil his minimum of 6 litres (I could only fit 5 litres) and to use DME to reach a boil gravity of 1.040 and like manticle says to add LME to get to where you want to be at 5-10 minutes before the end of the boil. Also, do not forget to stir it in.

Again no references here, but 1.040 is supposed to be a nice balance between a lack of utilization because of high gravity and tanin flavour extraction from boiling hops in too low a gravity.

 

[mosto]

:icon_offtopic: ...but does that mean a high gravity AG wort (or even a high gravity, full volume extract wort for that matter) will have lower hop utilization. If so, does software such as Brewmate and Beersmith account for this with their IBU calcs?

 

[rosshorne]

Yes http://www.valhallabrewing.com/dboard/dbnewsl/images/Image100.gif

and I think so. http://www.beersmith.com/Help/estimating_bitterness_tech.htm

When you change the OG in software the IBU's usually change.

 

[wobbly]

So if I understand Palmers chapter 5.5 where he talks about utilization vs SG vs time his table indicates that if I boil a wort of 1030 for 60 mins the utilisation will be around 0.276 where as a higher SG of say 1080 would only have a utilization of 0.176

Does this then mean that if I boiled the hops in plain water then the utilization would be much higher again as indicated by a close look (extension) of the nomograph on the same page.

Doing it this way could/would make the process easier and also prevent the LME from further caramelising during the boil

Any comments

Cheers

Wobbly

 

[manticle]

Common wisdom suggests that boiling in water is more likely to result in harsher tasting bitterness. Yes utilisation will rise but usually 1030-1050 is considered a good range to encourage both decent utilisation and smooth bitterness.

 

[rosshorne]

I agree with Manticle. If utilization is such an issue then look into extracts (which I would like to).

However, Mr Wizard suggests pH as an issue to boiling hops in just water, so then why not add lactic or other acids? He writes about it again in another question.

This is where the brewing water comes in. While the pH of the brewing water may be inconsequential, its ion concentration is of the utmost importance.
http://www.byo.com/stories/item/1493-the-power-of-ph

Braukaiser says that increasing the pH too much leads to a harsh flavour

Some posts in other forums suggest that the characteristics derived from boiling in wort or water diluted with wort are superior. Hot/cold breaks remove harsher flavours?

Using a second boil of pH optimized water, while dodging potential 'harsher bitterness', grassy flavours, and tannins seems like a bit of effort for a small increase in utilization. I like to make my recipe and just add more hops where they are needed.

 

[wobbly]

Just exploring the possibilities so in view of above comments will continue to boil in a wort of around 1040

Cheers

w3