Sorry in advance for the long post. I started reading Ray Daniels’ Designing Great Beers book and got to the target OG chapter. He starts out giving reasons why it’s important to hit target OG by saying it will affect the alcohol content and therefore the perception of the balance of malt and bitterness. He gave an example of a 35 IBU 1.045 beer that ended up short on OG at 1.035 and stated how this would be a totally different beer. I put in these numbers in Brewer’s Friend’s IBU calculator. Due to the lower OG, you would expect more isomerization and utilization of the same amount of hops. However, the IBU’s only went up to 38. Would we really be able to tell a beer that is 3 IBU’s more bitter than intended, or are there other factors at play here that he doesn’t explain? Would there be an assumption made here that a poorer extraction efficiency also means a poorer extraction of dextrins and other non-fermentables thereby reducing the maltiness of this beer further throwing off the balance?
Ray also stated that if you get a higher than expected OG, one solution is just to increase your volume of wort and make more beer to keep to your target OG. His example was an intended post-boil volume of 6 gallons. He kept to the target OG by increasing his volume to 6.9 gallons. If you were adding specialty grains to this beer, especially in small amounts, wouldn’t their contribution be diluted? Would you really have the same beer by keeping to your target OG in this example? Over this past year, I have made tremendous strides in dialing in my equipment and getting more consistent, so I don’t expect to run into these problems. BrewCat’s comment on a recent thread about why all grain brewers don’t brew with kits because many achieve higher than expected mash efficiencies got me really thinking that when I do brew kits (about 50% of the time), maybe I am not making the beer intended since I am also getting higher than expected efficiencies. I suspect once I finish reading Ray’s book, I’ll be much more confident in designing my own recipes and actually know what I’m doing when I do so. It’s a great book so far, but I would definitely read Palmer’s How to Brew first. It’ll make reading Ray’s book easier to understand.
You are not the odd brewer out. If you missed your OG by ten points, something went very wrong. You need to figure out what. Will diluting a beer your OG when your OG is too high make that much of a difference? Depends on the recipe and the how far off. Who gets that far off being too high though?
Diluting a gravity that is too high makes sense and 3 IBU’s would not be perceived by me but yes, what about the malt characteristics? Especially specialty grains. Again, who hits way too high.
Hit too low? Well there are a couple of fixes I can think of. Boil more and reduce the wort. That may caramelize or scorch the wort. Add some extract but again that really means more base malt and less of everything else.
So hitting the OG to begin with IS important. I’m usually ball park and not terribly concerned. Can’t say I ever had a problem with too high. Once in a while too low. That was either dough balls or channeling in the mash. Stirring well and slow sparging (yes fly sparging gang) fixes that.
Oh boy what a discussion… When I figure my SG-OG,which ever you want to call it, I use 1.038 for almost all my fermentables except table sugar, which I use 1.042. So, the specialty malts I use in such small amounts that they don’t bring much other than flavor to the party. My conversion is at 80%, except…. I’ve never been more than .5 too high, but I have been 1-2.5 below. I agree with dough ball conspiracy! And once in a while, now that I do BIAB, I will git distracted while mashing and my temp goes too high, over 168, conversion seems to have stopped and my SG is low…. Reading is good, the key is to employ what you read… even if you can just practice on paper before you actually brew. Sneezles61
First of all, I fell asleep within the first 10 pages the four or five times I tried reading that book, so take this all with a grain of salt…
But there’s a handy bitterness unit/gravity unit chart that you can find pretty easily online that shows the relationship between SG/OG and IBU and how the ratio affects the balance of sweet and bitterness and completely changes the flavor of a beer. If I read your question correctly, I would think that this is what he’s talking about, versus hop utilization changing the IBUs themselves (see above comment, haven’t made it that far so I don’t really know what he’s trying to say!).
From the example, though, if you were planning a 1.045 beer with 35IBU, that puts you solidly into the “extra hoppy” category of the chart. Drop your gravity down to 1.035 with the same IBU, and you’ll have a beer that will likely be unpleasantly bitter, ie, no “malt backbone” to balance the bitterness of it.
Then again, he could be talking about something completely different.
There’s a real simple remedy- check your SG at the 10 minute mark. If it’s lower than expected, add some DME. If too high, add some water.
Of course, if you calculated your mash efficiency then you probably already know how close you’ll be to projected OG, and you’ve probably already added the DME, or extra water as needed.