How to bake bread in space

Space travel can be boring. Voyages to Mars or the Asteroid Belt may sound exotic and exciting, but the fact is that most of the time there’s not much to see and not much to do. Wouldn’t it be great if morale on these long missions could get a boost by a reminder of home like fresh baked bread? Thanks to NASA’s “Space Apps” program, that might one day be a reality. Sixteen-year old “citizen scientist” Sam Wilkinson has come up with a way to make bread simply and efficiently using carbon dioxide and a slow cooker that is designed to work within the limitations of a spaceship’s galley.

Sam Wilkinson has come up with a way to make bread within the limitations of a spaceship’s galley (Photo:Shutterstock)

But this isn’t just a matter of astronauts sitting down to a breakfast of fresh, hot bread groaning with butter and jam (nice though that may be). The process also addresses a very serious problem as man ventures into deep space: how do you carry enough food to feed a crew on long voyages? Up until now, the cuisine on manned missions has consisted of pre-prepared, pre-packaged meals. They may have seemed like something off the menu of the future during the Gemini and Apollo missions, but from then right up through the missions aboard the International Space Station, it’s all just box lunches.

And that’s the problem. Pre-packaged meals take up a lot of space and the packaging adds a lot of weight. That’s fine for short missions in low-Earth orbit, but on a mission to Mars that may last two or three years, that’s a lot of plastic trays and squeezy bags to cart along. One answer to this is to carry food as raw, bulk material like on maritime ships. In other words, a Mars mission would ship frozen sides of meat, containers of dried peas, No. 10 cans of powdered eggs and sacks of flour - or better yet, unground grains. But in order to do that, future spaceships will need proper galleys and astro-cooks will need to know how to prepare food in zero gravity with the limited resources available on a spacecraft.

The science of bread

Bread is pretty simple. It’s basically just flour mixed with water. If you take this, flatten it out and bake it, you get an unleavened bread like a matzo or a tortilla. But if you want something more like a loaf of bread, you have to make what’s called a leavened bread. The key part of baking leavened bread is getting it to rise. If you don’t manage this, you end up with a freshly baked brick. This is usually accomplished by adding yeast. If the temperature is right and the proper amount of salt is added to control the process, the yeast cells will feed on the sugars, start to reproduce and as they do so, they give off carbon dioxide gas. This gas is trapped by the gluten in the dough, which forms bubbles and the dough starts to rise.

The alternative to this is using a chemical, such as baking soda or baking powder, both of which use sodium bicarbonate to produce carbon dioxide and are generally used in quick-rising breads, such as cakes or biscuits.

This has served bakers and householders very nicely for some six thousand years, but baking bread in space has its own problems. Any spaceship designed in the near future is going to be small, cramped, provide very small amounts of electrical power, ration cargo space like it was gold wrapped in gold and won’t have a galley anything like the one on the Starship Enterprise. It will very likely be some tiny, underpowered alcove intended to do too much with too little. Therefore, baking bread in such an environment has got to be as efficient as possible - more bread machine than artisan bakery. More important, it has to be able to work in zero gravity. All of this puts both yeast and any chemical leavening agent at a disadvantage. For one thing, the chemical version needs to be carted along, which adds weight. Yeast doesn’t necessarily have this problem, but the alternative is cultivating it during the mission, which may not be possible in zero gravity or be logistically feasible.

Space bread

This is where Sam Wilkinson’s process comes in. The magic of making bread rise isn’t in the yeast, it’s in the carbon dioxide and you don’t need to ship CO₂ on a manned spacecraft - you’ve got more than enough thanks to all those astronauts breathing. Wilkinson’s idea is to use this “found” carbon dioxide to make the dough rise.

 It’s actually very simple. All the astro-baker has to do is mix the carbon dioxide and the water in a sealed chamber at a pressure of about 2.5 atmospheres, which is about that of the average soda bottle. The CO₂ dissolves in the water to form carbonic acid and will remain that way so long as it stays under pressure. In other words, you’ve got a bottle of soda water. In another sealed container, you mix the water and flour. Once the mixture has a nice doughy consistency, you release the pressure, the carbonic acid reverts to carbon dioxide, bubbles form and the dough rises. This rising takes about 1.8 seconds, which is much faster than the usual hour or so needed with yeast.

Sam Wilkinson's approach uses “found” carbon dioxide to make the dough rise

The next step is to take the dough and bake it in a sealed, very low temperature oven at about 120 C (250 F) for one hour and ten minutes. This is a method that is commonly known as “crock-pot bread”. It takes longer than oven baking, but is much more efficient in terms of power. Only between 120 and 280 watts of power are needed to bake a loaf, which is a considerable improvement on the 1500 watts needed in an oven. On a power-strapped Mars ship, this is a significant savings.

Part of the reason for the sealing is to retain moisture and, according to Wilkinson, improve the Maillard effect, which is what forms a proper crust on the bread by the reaction of amino acids and sugars (this can also be done by a quick blast of heat after baking) as well as reducing crumb formation. This is of particular importance aboard a spacecraft because crumbs have given engineers the heebie jeebies ever since the first Mercury flights when they feared the aftereffects of John Glenn’s lunch would end up in the capsule’s machinery. That’s the reason why early astronauts’ sandwich cubes were coated with gelatin and why the ISS only serves tortillas.

At the moment, space bread is still in the proof of concept stage, but it may be that when the first astronauts land on Mars, they’ll have fresh pumpernickel for their sandwiches.

Sam Wilkinson runs us through his space bread baking process in the video below.