Major Noob Question: Does all the wort have to be boiled?

So, I was just reading around various threads and noticed some of the threads on kitchen brewing, using a heatstick to augment a stove, etc. I'm still fairly new to this, but I had a thought.

For people that are having trouble boiling a full AG batch on a stove, why does all the wort need to be boiled? What if you just boil 5 gallons instead of 7. Then, when the boil is done, add the last 2. Hop utilization should be the same since the SG of the wort won't change (it's different than doing a partial boil and adding water at the end). So here's my question: Does the wort actually need to be boiled for any reason other than hop utilization? Perhaps it's a stupid question with a simple answer, but there's only one way to learn I guess.

jaobrien6 said:

So, I was just reading around various threads and noticed some of the threads on kitchen brewing, using a heatstick to augment a stove, etc. I'm still fairly new to this, but I had a thought.

For people that are having trouble boiling a full AG batch on a stove, why does all the wort need to be boiled? What if you just boil 5 gallons instead of 7. Then, when the boil is done, add the last 2. Hop utilization should be the same since the SG of the wort won't change (it's different than doing a partial boil and adding water at the end). So here's my question: Does the wort actually need to be boiled for any reason other than hop utilization? Perhaps it's a stupid question with a simple answer, but there's only one way to learn I guess.

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Wort has to be boiled for several reasons- to kill the lacto that is always present in grain, so that you don't get a sour beer, to drive off the DMS precursors (volatile compounds that cause your beer to taste like cooked vegetables if not driven off by the boil), to get the "hot break"- the coagulation of proteins. Normally an hour is sufficient for all of these things to happen, but sometimes a 90 minute boil is used in beers that use alot of pilsner malt. Pilsner malt is low-kilned, so it's boiled longer to make sure all the the DMS precursors are driven off.

If you want to only boil 5 gallons, you could boil the other 1.5 gallons in a separate stock pot and combine at the end.

Yes, all of the wort needs to be boiled. DMS precursors need to be driven off and proteins need to be coagulated. Two gallons of unboiled beer in a seven gallon batch could be quite detrimental (hazy beer that smells and tastes of cooked veggies).

EDIT: Yooper beat me to it...which is good because I failed to mention the bacteria part.

Sort of a follow on question - what exactly does the hot break achieve, I know it is the coagulation of proteins, but what happens to the beer if this is not done?

mattd2 said:

Sort of a follow on question - what exactly does the hot break achieve, I know it is the coagulation of proteins, but what happens to the beer if this is not done?

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Cloudy beer.

GT

Cool, thanks very much for the responses! I figured there was a reason, but didn't really know.

I've run into this problem as well....

I have a 30qt boil pot that really only wants to boil 24 lest there are any boilovers. My solution?

I've collected another gallon or so in a separate pot and boiled for ~15 minutes prior to adding it to the main pot, which had 15 minutes left of boil on it.

So all in all, I boiled 6 gallons for 60 minutes, and one gallon for 30 minutes, combining for my final volume of 5.5-6 gallons.

Thoughts? is 30 minutes of boil enough to clear up the wort? Even if it is just for 20% of the wort.

To do this, would it be alright to let the other half of the wort sit while boiling the first hal? Say I were to mash as normal but instead of going from mash tun to boil kettle I went to another container. From there I would take what I could and boil it with hops, then cool and place in fermenter, then continue on and boil the rest with out hops.
I feel like letting the wort cool for those 60-90 min might be an issue, even though it probably wouldn't cool to much if used a drink cooler. I am worried that if I went to a bigger pot my stove wouldn't be able to handle it, plus I am trying to go on a small budget, money is more of a factor than time for me.

I'm a partial mash brewer meaning i use some extract for the base and then use additional grains (like 2 row) + specialty grains for flavor.

i boil a slightly concentrated batch. I have a 5 gallon pot and i make 5 gallon batches. Obviously, I can't boil 5 gallons of liquid in a 5 gallon pot without making a huge mess so I boil 4 gallons and then add the remaining water after the boil.

This is pretty common practice for those that don't have huge brew pots to work with. It helps to have a brewing calculator like brewsmith to help calculate for the differences. Doing a concentrated boil has an effect on hops utilization. Because you're boiling a liquid with much higher gravity you won't be able to pull nearly as much out of your hops. (in beersmith you can specify the extract or any other sugar source as a "late addition" and it will compensate your gravity and boil readings.)

Lately I've been experimenting with "late addition" of extracts meaning that I do a mini-mash / steep at 150-160 with my grains, remove the gains and then advance to the boil and add the hops per schedule. I do not add the extract until the last 10 minutes of the boil, just along enough to get the extract up to temperature to sanitize it.

This means that the majority of my boil is a much lower gravity so I get better hops utilization and it's easier to boil off those volatile compounds. The extract has already been boiled so i'm not really all that concerned about boiling that. I just need to get it sanitized and get it dissolved into solution.

I've heard some fairly well practiced brewers argue that you "must" boil the whole batch at volume and you must boil the extract the entire time. In the world of brewing I've learned to shy away from anything and anyone that says "must do this". In my own trial and experimentation I've found a good 50% of such advice to be complete BS. Test it for yourself and see what you think.

(note, i also NEVER make a yeast starter. It's pointless if you have good sanitation practices)

fermcap

merddyn2002 said:

Doing a concentrated boil has an effect on hops utilization.

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No, it doesn't. This is something that nearly all brewing software gets wrong, as do most home brewing texts.

Hops utilization is independent of boil gravity. Commercial brewers have known this for decades (e.g. the American Society of Brewing Chemists in 1989: http://www.asbcnet.org/journal/abstracts/backissues/47-14.htm says "In the range 10.5-13.5° P, no relationship between hop utilization and original gravity was found. ").

Listen to John Palmer's "What is an IBU, Really?" from 20 March 2008 where he talks about it (including apologizing for getting this wrong in the most recent edition of How to Brew):
http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2008

Basic Brewing Radio actually brewed the same recipe as a full boil, partial boil, and partial boil with late extract addition, then had the 3 beers measured in the lab; all 3 had the same IBUs. March 4, 2010 - BYO-BBR Experiment III:
http://www.basicbrewing.com/index.php?page=radio

More discussion here:
https://www.homebrewtalk.com/f128/estimating-bitterness-algorithms-state-art-109681/
https://www.homebrewtalk.com/f14/hop-utilization-178668/

Because you're boiling a liquid with much higher gravity you won't be able to pull nearly as much out of your hops. (in beersmith you can specify the extract or any other sugar source as a "late addition" and it will compensate your gravity and boil readings.)

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Late extract addition is still a good idea if you're doing a partial boil, since it helps with color and there may be some flavor changes from caramelizing a concentrated boil.

SumnerH said:

No, it doesn't. This is something that nearly all brewing software gets wrong, as do most home brewing texts.

Hops utilization is independent of boil gravity. Commercial brewers have known this for decades (e.g. the American Society of Brewing Chemists in 1989: http://www.asbcnet.org/journal/abstracts/backissues/47-14.htm says "In the range 10.5-13.5° P, no relationship between hop utilization and original gravity was found. ").

Listen to John Palmer's "What is an IBU, Really?" from 20 March 2008 where he talks about it (including apologizing for getting this wrong in the most recent edition of How to Brew):
http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2008

Basic Brewing Radio actually brewed the same recipe as a full boil, partial boil, and partial boil with late extract addition, then had the 3 beers measured in the lab; all 3 had the same IBUs. March 4, 2010 - BYO-BBR Experiment III:
http://www.basicbrewing.com/index.php?page=radio

More discussion here:
https://www.homebrewtalk.com/f128/estimating-bitterness-algorithms-state-art-109681/
https://www.homebrewtalk.com/f14/hop-utilization-178668/



Late extract addition is still a good idea if you're doing a partial boil, since it helps with color and there may be some flavor changes from caramelizing a concentrated boil.

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wow, thanks for the info. I always wondering WHY it was like that but I've not take the time to do side by side tests myself. Just goes to show that you always have to test this stuff out.

Thanks for the info