Today we will discuss boiling at altitude, why? Well, my last article about the science of the boil and kettle reactions got good feedback.

One person David Matuška a fellow brewer. Got in touch and said that he thought adding a section about boiling at altitude should be included.

He said and I quote:

“I was reading your article about boiling. Very interesting, just maybe you can add something about altitude. I’m brewing now 2 years in altitude of 2500-3000 and everything works totally different (mainly because boiling point is lower)”

David Matuška (brewer)

I had to agree, I’ve also brewed at 2,000 meters when I was brewing in Dali in Yunnan and Armenia. The boiling point was closer to 94°C than 100°C.

I was going to add to the original article but found there was enough material for a short (became much longer and difficult when I did more research!) standalone article.

What Happens the Higher You Go?

The higher up you go, the lower the boiling point of water. With a lower boiling point, you might need to add more hops to achieve the target bitterness of your recipe.

As the boiling point decreases so does hop utilization, when, compared to say a brewer at sea level. Again, if you need to learn about hop utilization please read my last article first.

So how does altitude affect boiling point? Well let’s take a look at the handy table I made:

Please note the above numbers will be explained.

Many of you have probably heard of John Palmer. One of the great writers in brewing. He wrote on the subject of brewing at altitude (“A look at Isomerization Reduction due to Altitude,” MBAA, Vol. 54, No. 3, 2017).

I will summarize what he wrote. For every 1,000 meters of altitude there is a 3.2°C drop in the boiling point of water. According to those figures I was looking at 93.5°C for brewing at 2,000 meters. Which is close to what I have observed in real life.

Boiling at Altitude – Hop Utilization

So, the next question is, how does a lower point affect hop utilization? As we discussed in my previous article, the alpha acids in hops goes through a process called isomerization during the boil.

I wrote the following:

“Hops contain alpha acid, which are the bittering compound, by boiling the hops in the wort these alpha acids are isomerized into iso-alpha acids. Iso-alpha acids are much more soluble in wort providing bitterness.”

The isomerization process happens when you boil, but still continues at lower temperatures.

Admittedly, at a slower rate. You will even get isomerization happening with whirlpool additions too, which will add further bitterness to the finished beer.

As stated in John Palmers article, we have some good data to work from these days.

There’s some accuracy in modelling off hop utilization versus temperature in the whirlpool. In his article Palmer used models from 2 hop experts.

They are Thomas Shellhammer and Mark Malowicki when putting his estimates together. According to the table above. The hop utilization when boiling at 2,000 meters compared to sea level, sees a 44% drop off in utilization.

This suggests you need to use 44% more hops to achieve the same bitterness at 2,000 meters compared to sea level. Palmer is talking about whirpool hops not boiling but…

Now, I have checked literature and it seems this model is commonly used by new brewers. In fact, the recommended hop usage for Beersmith software works using these numbers.

Please check the link here: High Altitude Beer Brewing and Hop Utilization | Home Brewing Beer Blog by BeerSmith™

Please Don’t Blindly Follow Software

As I say, I have brewed at higher altitudes at a few different breweries. I had this exact same issue with my last consulting gig. They used Beersmith to help with their recipe building.

It had worked well for them and the beers they made at their brewpub allowed them to expand to a production brewery. Love those guys and it was a pleasure to work with them.

We were looking to scale up recipes from 500 litres to 2,000 litres for the new production brewery. The Beersmith software wanted to use 40% more hops.

I think these are flawed; they are based of models for use in the whirlpool not for boiling hops. The amount more you might need to add is closer 10-20% depending on what altitude you’re at and boil for longer

I am still trying to find more definitive proof, through peer reviewed paper. However, I’ve not found too much right now. Here are two links to brewers stating similar finding my experiences:

Insights In to Brewing at High Altitude (thebrewermagazine.com)

The Weird Science of High-Altitude Brewing (craftbeer.com)

Finding Correct Data for Utilization at High Altitude

Please if you have some good sources to that I could work from, please share them with me.

The only other sources I could find for now were below:

This from Ray Daniels (which I have also seen used elsewhere):

HOMEBREW Digest #4125 Sat 21 December 2002 (hbd.org)

This is about altitude and hop utilization.  My information on this subject came from Garetz (Using Hops, 1994). On page 137, he gives a correction factor as follows:

TF = Temperature factor.

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

Multiply your wort volume by this factor in IBU or hop weight calculations to apply the correction. 

Also, this site Real Beer also has similar views:

Norm Pyle’s Hops FAQ (realbeer.com)

He is using Garetz too…

“According to Garetz, there are several adjustment factors, that he brings together in the formula with the term “combined adjustments” (CA):

CA = GF * HF * TF

Where GF is the Gravity Factor, HF is the Hopping Rate Factor, and TF is the Temperature Factor.

To calculate it all, he starts with some he calls CF:

Concentration Factor:  CF = Final Volume / Boil Volume, to account for concentrated boils of extract brews.

Next, calculate Boil Gravity (BG):

BG = (CF * (Starting Gravity – 1)) + 1

Then calculate GF:

                BG – 1.050

GF =   —————————     + 1

                     0.2

HF is calculated as follows:

HF = ((CF * Desired IBUs)/260) + 1

TF is based on elevation as follows:

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

These are all put into the following formula, along with the utilization from the table, and the IBUs are calculated.

Note two things:

1) The utilization and alpha acids should be expressed as whole numbers (7% = 7), and…

2) This process is iterative, since it contains a term (HF) based on your goal IBUs.

You must guess at the final result, do the math, and rerun the process, each time adjusting the value downward. It takes a little practice, but can be done.”

So, let’s throw these figures into some examples:

At 5000 feet you would divide your utilization by 1.18 which is a reduces your utilization by approximately 15%.

((5,000) / 550) * 0.02) + 1= 1.18 => 100/1.18 = 84.75 so 15%

At 2,000 (6,561 feet) meters which I have brewed at before would mean dividing your utilization by 1.23 approximately. Meaning you’re at around 19%.

((6,561) / 550) * 0.02) + 1= 1.23 => 100/1.23 = 81.30 so 18.7%

As we show in the above table, the effects using this method are significantly different from those used by Beersmith. As I say I will continue to look into this further as I have more information to go off of.

Greater Evaporation Rates – Boiling at Altitude

When you at higher altitudes their air is usually drier (less humidity) too. This is due to lower air density pressure and the temperature that accompanies the change in elevation.

When you factor in lower boiling point as we’ve explained above, you’ll get more liquid vapor for the same amount of applied heat.

In plainer English, you get more liquid boiled off the higher the altitude. If you brew in the mile-high city of Denver you might lose 5.7 litres per hour compared to 3.8 litres using the same set-up at sea-level.

When it comes to boiling though there are many factors that can affect boil of rates from burner size, kettle geometry and the weather on the day of the brew.

As I have said in many of my articles, recording data is your best friend. To truly understand how your brewery works writing everything down because over time you will see patterns and better understand your brewery.

This will allow you to dial in your standard operation procedures and improve your overall beer quality.

Boiling at Altitude – Conclusions

When I first looked in boiling at altitude, I didn’t know what I was letting myself in for.

This is a subject where there isn’t much readily available research to go off of. I worked with what I found and shared it with you. I will be following up on this subject as, and when I get more information to work from.

–>So, if you’ve any more relevant information please share with me <–

Below I have the John Palmer findings I wrote about earlier.

Click here for John Palmer’s “Uncovering the IBU”

Thanks for taking the time to read this article. If you have feedback the n please feel free to share with me.

I do want to be able to go into more details at a later date. So, having more input will only help with that…thanks again and happy brewing!

Cheer

Neil