Fostering curiosity in kids (and their parents) since 2011

“Why do you have to change baking recipes at high altitudes?”

fresh baked brownies in a clear baking pan

My newly minted middle schooler is going to be so excited to see these! (Photo: Shala Howell)

Hi all, it’s back to school time here at Caterpickles Central, which means my annual summer hiatus from blogging about the random questions that pop up in our lives is over.

But before I get into today’s question, I’d like to mention that while I may be an indifferent blogger over the summer months, I am an excellent Back to School Mother. I know this because:

a) I don’t post back to school pictures on my Facebook account, Twitter feed, or blog.

b) I do bake batches of End of the First Week of Middle School brownies.

I used a brownie mix, of course, because I also have a house to clean, a summer’s worth of laundry to do, bills to pay, and a book to write. Which brings us to today’s question.

I normally skip over high altitude baking instructions because they have never been relevant to my life, but today, for whatever reason, they caught my eye.

My brownie mix said to add extra flour and water in high altitude locations and I couldn’t help but wonder why.

Why do you have to change your baking recipes at higher altitudes? 

I don’t know how much time you spend at the King Arthur Flour website, but now that I bake my own bread 15% of the time, I visit their website pretty frequently to trouble-shoot various baking calamities. So of course, I trundled over there immediately to see what their baking experts had to say about this issue.

True to form, the King Arthur website has several charts talking about how to adjust the oven temperature, liquid, sugar, and flour to compensate for the effects of baking at high altitudes. They advise changing one ingredient at a time to see what works, and to keep in mind that what works for your neighbor up (or down) the mountain may not work for you. But while the King Arthur website provides lots of glorious detail on how to compensate for the effects of baking at a high altitude, they don’t spend much time explaining why all that compensating is necessary. They mention once that the lower air pressure is to blame, and leave it at that.

Clearly, I needed to look elsewhere if I wanted to glimpse the science behind this particular cooking anomaly.

Fortunately, The Accidental Scientists at the San Francisco Exploratorium have a lovely and detailed article on just this issue. The lower air pressure at high altitudes affects baked goods in two ways:

  1. They rise more easily
  2. They lose moisture much more quickly

Let’s look at each of these one at a time.

Why do baked goods rise more easily at higher altitudes? 

I’m going to assume that you, like me, are used to dumping baking soda, baking powder, and yeast into your batters and doughs without thinking too much about why you’re doing it. Briefly, chemical leavening agents like baking soda and baking powder help baked goods rise by creating carbon dioxide pockets when mixed in the batter and heated. Baker’s yeast, on the other hand, interacts with the sugar in your dough to create pockets of carbon dioxide (and apparently other things that flavor the bread).

These chemical reactions happen much more quickly in a low air pressure environment. Lower air pressure means less force from the surrounding atmosphere to counteract. As a result, the gas bubbles created by the leavening agents grow faster and larger. If you’re lucky, the worst outcome will be a cake or a bread that is more coarsely textured than you’d like. But if you have my luck in the kitchen, what will really happen is that the gas pockets created by these chemical reactions will expand so quickly and so forcefully that the air pockets burst and your cake collapses.

Now for the second question.

Why do baked goods lose water more quickly at higher altitudes?

It turns out that water only boils at 212°F at sea level. Everywhere else, the boiling point of water is affected by a number of factors, including air pressure. Water boils (or evaporates) when its internal vapor pressure equals the pressure exerted on it by the atmosphere. At sea level, achieving this equilibrium takes 212°F worth of heat. Higher altitudes walk hand in hand with lower air pressure. And the lower the air pressure, the lower the temperature at which water will boil.

What does this mean for baking? Basically, the water vapor (or steam) which helps your baked goods rise will be generated more quickly (and dissipate faster). Your bread, cookies, cakes, and brownies will be drier and the sugar in them more concentrated. Your lovely baked goods will stick to your pans. Your cakes won’t set, or if they do, they will be astoundingly dry.

So, will adding extra flour and some extra water to my brownie mix fix it? 

Maybe. Maybe not.

The effects of baking at high altitude vary depending on how far up or down the mountain you are. That extra dose of flour and water might do enough in some places, but if you’re serious about your brownie texture, you may need to do some extra experimentation. The real answer may be to reduce your oven temperature or shorten the cooking time. Or maybe you need to cut out some of the sugar or add an egg white.

I wish I could provide you with an easy answer, but the best I can do is point you to the nine tips on The Accidental Scientist’s blog and the lovely detailed charts on the King Arthur website.

Good luck.

Related Posts: 

3 Responses to ““Why do you have to change baking recipes at high altitudes?””

  1. Alexander Gerber

    Thank You for this, Shala.
    In fact, the rising AND the lost of moisture base on the same principle, instancing differently on different altitudes. It’s the air pressure impacting water molecule structure behaving differently. Temperature is another important aspect in the thing.

    I use another example to remind people on this effect: I ask them “Why it is impossible to boil eggs hard on the Mount Everest?”

    I plan to write the “Systemic Cook Book” – when I find enough time for it.
    My idea is, to unveil root causes like this air pressure thing behind phenomena You can witness every day and all around. Sometimes, You just wonder. Sometimes, You want to use an effect to turn Your cake crispier. Sometimes, You will make it yummier by adding pinch of salt. Or You add some pinches of sugar to Your sauce to create complexity in flavor.

    Your post reminds me of. I think, there are people out there, who share the same questions.
    It might be a good idea to share answers, also.
    I started the book project, to have a place to stop and to show up.

    Here it is:


    • Shala Howell

      Thanks for stopping by Caterpickles and for taking the time to find me on Twitter. I look forward to watching your book evolve.

      One of the things I found fascinating in reading the background materials for this post is that while low air pressure makes breads etc. bake more quickly in the oven, it actually makes foods cooked on the stove take longer. This makes sense when you think through it because it’s the lower boiling point of water at play in both situations. In the oven, the lower boiling point means water becomes steam more quickly, while on the stove, foods that rely on heat acquired from boiling water (such as stews, soups, etc.) will take longer to cook because the water boils at a lower temp and there’s less heat available. So interesting.

      It makes me think about kitchen tools like sous vide cookers, which work by heating water to a precise temp and keeping it there while the food in the little vacuum-sealed baggy cooks. In this situation, the cooking time probably wouldn’t be affected, but I wonder if for the longer-term recipes, such as 36-hour pulled pork, mountaintop cooks have to top up the water in their giant pots more often than cooks in the valley.

      Sadly, we live at too low an elevation to test this, but the next time we find ourselves in Salt Lake City or Denver or some other really suitably high altitude place, I’m going to take a selection of pots and pans along with me, so that I can test out some of this stuff.

      Liked by 1 person

      • Alexander Gerber

        I see You are on another track to where I also head to. 😉
        I always find joy in these share of destination and experiences about the road to get there.
        It is never ‘one’ – Do You have ‘Lucy’ by Luc Besson on Your watchlist?


What are you thinking?

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Basic HTML is allowed. Your email address will not be published.

Subscribe to this comment feed via RSS

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: