I have a 7.5 gal pot, which is just not quite enough space to make enough beer to fill up my 19L secondary carboy. I want more beer. To achieve that without buying a new pot, please tell me if I’m thinking about this correctly:
Say a given recipe gives me, post-boil, 5 gal at 1.050. I like the beer, but I want it to be 6 gal, or 20% more volume. To achieve that, in the next batch I could adjust the grain bill to increase the OG by 20%, which is 1.060, but still use the same amount of strike and sparge water as the first batch. At the end of the boil I will have 5 gal, but the OG will be 1.060. I then dilute the batch with an additional gal of water. I will now have the same beer as the first batch with an OG of 1.050, but 6 gal instead of 5.
This will work fine, except… your beer might indeed taste a little bit like it was watered down. I’ve diluted many beers, and it’s close but not quite as fantastic as if you had brewed up the full 6 gallons of 1.050 beer with the proper equipment. That being said, it’s certainly worth trying so you can decide for yourself. I am kind of picky and self-critical and tell myself that I can taste a difference, but on the other hand I have never run blind experiments to know for certain if there truly are any flavor impacts. In theory, there should be very little to no impact. So, give it a try and find out.
This actually gets to the heart of my question. Why would diluting, i.e. adding water to make it less concentrated, make a difference, when boiling is nothing more than the opposite, i.e. removing water (through steam) to make the beer more concentrated? Why would doing what I propose make the beer taste “watered down” if the ppg, meaning the ratio of sugars dissolved in the wort, is the same? Seems to me that, if there’s a difference, it’s because the volume of liquid affects the taste of the what’s being cooked in some fashion. In other words, does cooking a concentrated wort affect all the non H2O compounds differently than cooking a more dilute wort? I don’t see why it would, but food chemistry is awfully complicated. A blind taste test might be interesting…
I’m not saying it will here but as you say food chemistry is complicated stuff. The big things going on in the boil are, as you pointed out, removal of some excess water, Isomerization of hop oils, Coagulation of proteins, and maillard reactions. The Osomerization is affected by a concentrated boil but it’s probably only noticeable in a situation where you are intending to max out the possible isomerization levels in your finished beer. that level will be the same per gallon (more or less) in your 1.050 wort or your 1.060 wort so if you want 100 IBU in your beer and you can only get 100IBU total in your wort you are adding 1 gallon of 0IBU to your 4 gallons of 100IBU ending with 5 gallons of 80IBU. that’s a pretty big difference on paper. I don’t realistically know if you would actually taste the difference though.
coagulation of proteins is dependent on pH as well as temp and I suppose your pH is going to be a bit lower with the more concentrated wort but this is easy to adjust.
Maillard reactions are dependent on pH, temperature, Sugar, and amino acid concentrations. you will have a higher concentration of amino acids in the 1.060 wort than in the 1.050. This would, if anything, I imagine make the reactions more intense which may or may not be what you are after and may or may not be noticeable.
all that said I don’t think it’s going to make significantly bad beer to top off assuming reasonable sanitation.
You could even top off with ICE which would give you the benefit of knocking a couple degrees off your temp as well. In fact, if you ‘topped off’ with 20% of your finished volume with ice you could knock your wort from 110 degrees to 64 instantly. and that’s pretty cool (no pun intended)
Just go for it. As I said, I do this all the time with 10 gallon batches. I top of about 1.5 gallons at the end of boil. I boil it while mashing and set it aside with a lid on until I need it. Keep the amount small and you won’t hurt anything. I won a pro-am with a beer that was topped off.
I used to dilute a bit when I started out. Honestly, diluting only a gallon, I don’t think you’d likely notice in most styles at all, as Steve said. EXCEPT in something like an IPA, where you count on that healthy slap of bitterness up front. I remember noticing a slight loss of bitterness (ie, isomerization) when I diluted - not a lot by any means, but noticeable. If you brew a beer and notice a slight loss of bitterness, take good notes and maybe increase your bitterness and flavor additions by 5 or 10% the next time, if needed. I say no worries.
Another thing I do from time to time is sort of a faux partigyle. I add the gallon and a half to 4 gallons making a small beer leaving 5.5 gallons full recipe. It actually works pretty well, even with hoppy beers. I’ve been meaning to do it with Janet’s brown or a while.
To me the difference is that the dilution water was not along for the full ride. It will be different but not on a level that the average joe could pick out
I have a an 8G stockpot and have no trouble getting over 19L in the fermentor as long as I don’t boil the living crap out of the wort. The wort needs to be boiling, not jumping out of the pot. I get it to a nice gentle boil for the first 40 minutes then turn it up a little if I need too. It also helps if I use pelletized hops instead of whole hops. Yes, I’m starting with a slightly larger pot but I usually end up with more beer than I can fit into the keg.