Separate Boils - Hopping Sparge Water

[JoeSchmoe]

I've researched this a bit, but can't find anything conclusive.

I was thinking there could be some theoretical advantages if one were to do a split boil between your main wort pot and a separate sparge water pot.

The main pot would obviously be much bigger. In this pot you wouldn't put any hops in so boiling times could be minimized. You'd simply be boiling it for sanitation, and possibly DME avoidance, though I would only want to try this on malts where DME were less of a concern.

In your side pot, you boil your sparge water. I do BIAB and sparge into a separate pot. I'd imagine the SG of this wort is much lower than the main pot. In the past, I've dumped this water into the main pot. Instead of that, I'm thinking I could boil your hops separately. In using the calculator below, you need MUCH lower boil times to achieve the same IBU when the gravity is lower. As such, if you could get the same bitterness out of a 20min boil in your side pot compared to 60min in your main, you'd have the advantage of retaining more hop aroma/flavour.

https://www.brewersfriend.com/ibu-calculator/

Of course the time and energy saved by the lower boil times would also be a factor. That hard part would be running the calculation to get the right overall IBU's once the sparge water is added back in. Of course the calculator is theoretical only, and may have some practical limitations.

Has anyone tried this, or something similar?

Edit: the other advantage is if you had a concentrated main wort pot, you could play around with how much sparge/hop water, and possibly additional water to get two beer types. Say an APA and Blonde Ale out of the same batch.

 

[IslandLizard]

Aside from boiling off DMS, isn't one of the reasons to boil the wort for an hour to condense it, thus raising the gravity?

 

[mac_1103]

In using the calculator below, you need MUCH lower boil times to achieve the same IBU when the gravity is lower.

And then you're going to dilute those IBU into the rest of the wort, so you will need to achieve higher IBU rather than the same IBU.

 

[JoeSchmoe]

And then you're going to dilute those IBU into the rest of the wort, so you will need to achieve higher IBU rather than the same IBU.

Of course. Say if your sparge water was a third of the volume of the overall wort, I take it you'd need 3 times the IBU in the calculator to get your final diluted IBU.

I.E. if you want a final IBU of 33, you could shoot for 99 in the sparge water.

The main gist of what I'm say though is if your main pot was 6gal of SG 1.060, and you boiled 2oz of 7% hops for an hour, you get an end IBU of 40.

If you had the same hops in 2gal with an SG of 1.015 for 20min, you'd get 109IBU.

If you took that 2 gal of 109IBU and mixed it with 4 gal of 0IBU, your end IBU would be about 36.

So the net result is similar IBU, less boil time, more potential aroma/flavour. Of course you'd have to math up your SG's a little more as well, but you can see what I'm saying.

I initially came up with this idea, since I'm more of an APA guy whereas my friends are more lower IBU beer drinkers. This method would allow two different IBU (and ABV depending on how much additional water is used) beers out of the same batch.

 

[Zadkiel]

Dunno what the consequences would be of not coagulating all those proteins in the main mash wort would be, maybe they'd still setlle out in the fermenter, and you'd end up with all the trub in there instead?

 

[Zadkiel]

I initially came up with this idea, since I'm more of an APA guy whereas my friends are more lower IBU beer drinkers. This method would allow two different IBU (and ABV depending on how much additional water is used) beers out of the same batch.

There's a name for this technique if you want to look it up, it's called Parti-Gyle brewing, where you make 2 different beers from the mash and from the sparge. Typically you still boil both though. Your way would have no hops in the first runnings.

 

[BrewnWKopperKat]

This seems similar to the "partial boil with late additions" process that "stove top" extract brewers can use.

In that process, the boil is done with roughly half the DME/LME, half the water, and all the hops. The remaining DME/LME is added shortly before/after flame-out (historically for pasteurization) and the remaining water is while moving the wort to the fermentor.

How to Brew, 4e (2017), has a lot of details on this process including some limitations on number of IBUs in a volume of wort (before dilution).

I initially came up with this idea, since I'm more of an APA guy whereas my friends are more lower IBU beer drinkers. This method would allow two different IBU (and ABV depending on how much additional water is used) beers out of the same batch.

If you're interested in further feedback: pick two beers, outline the ingredients for each beer, outline the brew day steps, and post the information.

I can see where this might work for two beers that had two very similar grain bills. But I don't see the process (limited to two kettles and two heat sources) working for most combinations (for example, a blonde ale and a Red IPA).

 

[IslandLizard]

Aside from boiling off DMS, isn't one of the reasons to boil the wort for an hour to condense it, thus raising the gravity?

Again, how do we get rid of the Dimethyl Sulfide (DMS) in the main/high gravity, first runnings batch?

 

[JoeSchmoe]

Again, how do we get rid of the Dimethyl Sulfide (DMS) in the main/high gravity, first runnings batch?

How much of a concern is it with non-pilsner grains? Say straight 2-row pale ale. Would a 20min boil do it?

 

[BrewnWKopperKat]

@JoeSchmoe : have you seen this topic here at HomeBrewTalk?

Is there a limit to the IBUs you can get in wort?​

eta: you're welcome.