How does altitude affect brewing?

[Afghanvet_2x]

So I am moving to Colorado, right now I live in North Carolina, my question is how does the altitude affect mash temps. I know water boils at a lower temp. so will the startches turn to sugar at lower temps? I have also heard hop utilization will be lower by about 15%, does anybody have any insight on this? I do all grain by the way

 

[Rotgutt]

Mash temps are mash temps, there's no difference. Water does boil at a slightly lower temperature but I've never bothered to add time to my boil.

 

[Beernik]

I'm at 5500 feet. Water boils at 200F.

Theoretically, you might get less bittering due to the lower boil temp, but I've never worried about it.

My main annoyance is having a mash calculator that assumes the boiling water addition for stepping up the mash is 12F hotter. I always have to use extra water. (BrewPal used to let me adjust that setting, but an update eliminated it.)

Also, you might have an extra percent of two boil-off because of the lower pressure and drier air.

 

[tgmartin000]

My hop utilization is about 20% lower.

 

[riored4v]

My hop utilization is about 20% lower.

Interesting. Guess I had never though about hop utilization being so much lower. 20% is pretty significant. Makes me think I should go in and recalculate all of my recipes now.

 

[November]

My hop utilization is about 20% lower.

I'm at about 5000 ft, but I have never noticed a reduction in hop utilization. 20% is pretty significant. How did you determine a 20% reduction, lab analysis, a utilization formula, comparisons? Just curious if I need to examine my hop usage.

 

[Beernik]

I think the formulas indicate a 20% drop, but I can't believe I get 20% less IBUs. That's a 10 IBU reduction on a 50 IBU beer. I'd be willing to accept a 2 - 5 IBU drop, but 10 just doesn't feel right.

My advice is if there is something you make regularly, make it first and make it normal. See if you can taste the difference, and how much it is.

 

[FarmerTed]

I adjust for the lower pressure (about 620 vs. 760 torr) when I'm bottling my beers. I usually add about 2.0 volumes of CO2 to my beers at bottling (in addition to the residual CO2 left after primary), but this means I add about 20% less sugar at bottling. There's nothing more annoying than cracking open a bottle of Sam Adams at altitude, putting it down for two seconds, and having it gush all over the place due to the lower atmospheric pressure.

 

[tgmartin000]

I'm at about 5000 ft, but I have never noticed a reduction in hop utilization. 20% is pretty significant. How did you determine a 20% reduction, lab analysis, a utilization formula, comparisons? Just curious if I need to examine my hop usage.

I calculated it based on this thread:

https://www.homebrewtalk.com/f14/brewing-high-altitudes-292790/

Which contains this equation:

TF = ((elevation in feet/550) * 0.02) + 1

This equation gives you a factor to multiply your hop additions by. At 5280', it equates to about 1.2, meaning you need to add 20% more hops to compensate.

All I really know for sure is that I use an 80% hop utilization factor in beersmith. My recent Zombie Dust clone was pretty close to the original, in bitterness.

A lab analysis would be an interesting idea, though. Looks like ajdelange could do it, otherwise it's kinda pricey.

 

[Beernik]

I found this slide show comparison of the different formulas: http://www.nthba.org/www/docs/Brew Day Presentation - Hop Bittering.ppt

The thing is there are so many factors in utilization:
1. Longer boil times increase it until ~ 60 - 90 minutes.
2. Wort temperature (boiling, FWH, whirlpool hops) increases it.
3. Boil vigorousness increases it.
4. Isomerization decreases as SG increases.
5. There is a maximum utilization of about 100 IBUs.

I don't think the Garetz reduction for elevation should be linear. It seems to me that it over estimates the reduction in isomerizarion for larger IBU boils. In other words, I think it might be more accurate for a 20 IBU beer where it says you lose 2 IBUs than a 50 IBU beer where it says you lose 10 IBUs.

I'm definitely not an expert on this issue. But that's what my gut feeling is.

 

[303Dan]

I'm in Colorado as well. My boiling temp is 203.5. I have changed my hop utilization in BeerSmith to 85% and I feel like I'm getting what I expect now.

Other than that, the only thing I do differently is adjust my kegging pressures according to a couple charts I have. Generally it's around 2.5 additional psi compared to sea level to get the same carbonation level for me at about 5000 ft of elevation.

 

[Gameface]

Can't believe I've never considered altitude before. I'm at 4500'. I know my boiling point is lower, at about 204f, and I've always felt like I'm not getting the ibus beersmith tells me I'm getting so I've just gotten into the habit of shooting high.

 

[Cyclman]

First off, welcome to Colorado. I have not noticed a dramatic reduction in bitterness in beers I brew, but obviously, things are subjective. I can't imagine a 20% reduction, I would think that would be highly noticeable.