Mad About Science: High altitude magic

By Brenden Bobby
Reader Columnist

Have you ever baked something — especially in this area — only to discover that it didn’t come out quite like you had hoped? The air around you may be the culprit.

This week’s subject is courtesy of East Bonner County Library staff member Vanessa Thiele. Thanks, Vanessa!

If you are an avid baker, you have probably noticed that some recipes call for different amounts of ingredients when baking at higher elevations — in other words, anything over 3,000 feet above sea level. The reasons for this are rooted in the science of air pressure and how it affects water evaporation.

Atmospheric pressure is greater the closer to sea level you are, as there is more air pressing down on you from above. While air pressure changes this minuscule are virtually imperceptible to humans, we can see the effects of pressure displayed more dramatically in the ocean. Simply put: the deeper you go underwater, the greater the pressure becomes. As more pressure is exerted on you, it alters the way your body can process gasses like oxygen and nitrogen.

If you were to don scuba gear and dive deep into the ocean, then rise quickly, the change in this pressure would cause something called DCS, or decompression sickness. If you were to travel from a high-pressure area (deep water) to a lower pressure area (returning to the surface) very quickly, your body would not have time to properly process the nitrogen you’ve inhaled from your scuba gear, and this gas would get trapped in your blood vessels and tissue, creating bubbles. This causes a host of bad symptoms from dizziness and nausea to joint pain and skin rashes.

Pressure is a big deal. Just ask any high-school student.

Air pressure — and the lack of thereof — has an interesting effect on baked goods. Lower air pressure at higher elevations allows water to evaporate from dough more easily, as there is less pressure keeping the water in place. This will often result in drier and more crumbly baked goods.

Lower air pressure doesn’t just affect the moisture of a baked good, however. It can also influence more air.

Air is important in baking. Yeast needs air in order to maximize its cellular growth — in so doing, creating waste in the form of carbon dioxide. I’ve talked before about how bread becomes pillowy because it has been well aerated by what are (essentially) yeast farts. Yeast will produce less CO2 in the presence of low air pressure; and, because there is less pressure exerted on the surface of the dough, the CO2 that they do manage to produce will more easily escape the dough.

This principle is exemplified by whipped egg whites, used for things like meringue pie to create white peaks of delicious, sugary goodness. Less air pressure makes it easier for oxygen to escape the aerated egg whites and cause the structure to break down and collapse, which can lead to a flat and disappointing meringue.

Luckily for dessert lovers everywhere, all is not lost when baking above sea level. A slight increase in moisture can help offset the effects of lower air pressure — the presence of more water compensates for what will naturally evaporate during the baking process. This can be achieved with simply adding water or by adding something with a little more substance, like an egg yolk, which also contains fats, cholesterol, potassium and protein.

Fats and cholesterol aren’t entirely bad for you. Fats are a necessary part of the human diet, which allow our bodies to process calories into useful energy that — our brains in particular — can use to keep functioning. It’s a misconception that consuming fats will make you fat. There is overwhelming data suggesting that the majority of weight gain and obesity can be attributed to two major factors: genetics and sugar consumption. 

Sugar appears in a frighteningly large portion of American meals. White breads contain a huge amount of sugar, both to feed the yeast during the baking process as well as making humans crave more after consumption. The biggest offender, however, is most definitely sugary beverages like soda.

That being said, all sugar isn’t bad. Sugar from fruit is extremely important for our brains to function, in addition to all of the vitamins and nutrients naturally present in most fruit — provided it hasn’t been processed and doused in cane sugar or high fructose corn syrup. Those forms of sugar aren’t very healthy, but their potential to build fat can be mitigated by exercise.

Returning to the subject of this article, barometric pressure can do more than wreak havoc on your crème brûlée. Sudden changes in air pressure — such as the presence of a low-pressure air system pushing into town ahead of a rain storm — puts less pressure on our muscles and tissue, allowing them to expand. 

This expansion is completely imperceptible to most of us, but those who have suffered from a traumatic injury — such as a broken leg, in my case — may find their joints aching when bad weather comes on. This expansion acts similar to swelling, and can cause the expanded tissue to press against nerves in sensitive areas like our knees, elbows or knuckles, resulting in aches and pains.

Thanks again for the topic suggestion, Vanessa. You managed to convince a guy that can’t eat wheat to pen an article about baked goods.

Stay curious, 7B.

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