Hop Utilization with SG < 1.030

I've found the tool on Brewtoad to be a little inaccurate (I haven't found a way to alter the SG of a partial boil... possible?), so I use Palmer's chart for utilization. However, my theoretical gravities tend to weigh in beneath his low end (1.030); I'm clocking at 1.015-1.025. Couple of questions:

1) Is a gravity < 1.030 problematic for flavor profiles? Problematic for anything?

2) Short of creating a regression, is there any numbers/experience with partial boils this low?

3) Would anyone recommend dropping some extract after my mini-mash to hit 1.030 or is this current procedure fine?

The reason I bring this up is b/c Brewtoad is clocking my recipe in at 51 IBUs whereas my homework calculations are hitting 122. Thanks!

 

Yes. All that counts is the pounds of extract (sugar) and the pounds of water. If you have a wort of a certain SG you determine its weight by multipling by the density of water and the volume. Then convert SG to Plato to determine the amount of extract. Determine pounds of extract and water in the desired target and adjust whichever one (or both) to give the desired gravity and desired volume.

If you are doing a very small beer (Berliner Weiße) no. If you are trying to do a medium (Pils) or large (Bock), yes.

As noted above the experimentation has all been done for you and is found in the Plato tables.

As noted above that depends on what your target is.

There are, of course, several models for bitterness some of which are parametric (meaning that there are, in effect, an infinite number of models). Add to that the fact that the alpha content of the package in your hand may deviate substantially from what is on the label and it is therefore pretty much the case that the only way to determine bitterness is to taste beers with known bitterness to the point that your palate gets calibrated or send the beer out for analysis.

 

When I refer to a SG < 1.030, that's my partial boil gravity. Late boil, I'm driving it upwards of 70+ points. With a partial boil gravity of 1.020, am I going to have any issues?

 

I'm not clear on what you are doing. I would interpret this sentence to mean that you start with a gravity of 1.030 and boil away enough water to reach 1.100. I'm pretty sure that's not what you mean.

Issues with what? Hop utilization? The wisdom is that hop bittering principle dissolves/isomerizes more readily in low gravity wort. OTOH if you are really mashing and obtaining runoff at 1.020 there are clearly issues with your mashing and sparging techniques unless this is the 'small beer' from a partigyle brew.

 

AJ I think he's saying he is doing a mini-mash and getting say 2-3 gallons of low gravity wort (<1.030sg) then boiling that down...adding a bunch of extract to increase the gravity to 1.070+.

GingerFlock,
If I'm understanding this correctly you shouldn't have any hop utilization problems doing this.

 

Thanks mors, that's it! I'm wondering, though, if there is are coefficient values for SG's less than 1.030 (Palmer's chart only goes to 30).

 

This website has some formulas you can use: http://www.realbeer.com/hops/
But there has been considerable debate recently about whether the gravity factors are actually correct, especially with extract brewing. You'll have to decide for yourself.

 

Thanks! In your opinion, do you think utilization is more a function of time or gravity? I know its a combo of both, but are you saying that time's the more important factor here?

 

Time is definitely a factor - gravity might be. To be on the safe side, I do my partial boils at roughly 1.040 SG, and use the Tinseth utilization formula. That way, it should be a pretty good estimate of utilization whether the gravity factor is valid or not.