Many vitamins will degrade over the duration of, for example, a mission to Mars, but polymer microgels could stabilise them long enough

Micrograph of a microgel

Atomic force microscopy image of microgels used for the encapsulation of retinol. © Ricarda Schroeder

Almost half a century after the first Moon landings, the next frontier of manned spaceflight—an expedition to Mars—is capturing our attention. But before the first Mars-bound astronauts can take off, many questions must be answered, including the most basic: what will the astronauts eat?

The actual journey to Mars is estimated to take a few months, but if food is to be used throughout a whole mission, it will need to stay nutritious and palatable for up to three to five years. This is far longer than the 18- to 24-month ‘shelf life’ of most food items currently consumed in space.

Essential nutrients, such as vitamins and amino acids are particularly problematic, as they degrade in long-term storage, acquiring strange tastes and, more importantly, losing their nutritional value. Ricarda Schroeder of the European Space Research and Technology Centre has now shown that it is possible to stabilise one such nutrient, vitamin A1, by packing it into a polymer microgel. Her work is published in the journal Life Sciences in Space Research.

Vitamin A1, also known as retinol, is important for maintaining healthy skin and blood and good vision. It is relatively unstable and can be easily broken down by oxygen, heat or ultraviolet light to form compounds that are either inactive or, worse still, toxic. Schroeder’s work has the potential to solve this problem; she found that retinol increases its stability when it is absorbed by polymer microgels.

These microgels consist of porous, colloidal particles with a crosslinked polymer network structure; the size of the pores decreases as the number of crosslinks rises. Schroeder prepared lightly-crosslinked microgels, diffused retinol into them, and then added further crosslinks, reducing the amount of space available for the bound retinol and thus reducing its opportunity to degrade. “The retinol bound into these microgel particles could be almost 100 times as chemically stable as unbound retinol,” she explains. “Vitamin A stored in this way should, therefore, remain intact for at least the length of a mission to Mars, and the method could in principle be used to stabilise other vitamins and nutrients.”

Schroeder started her career as a chemist and studied microgels during her PhD research, but she has always been interested in space and was delighted to be offered a chance to combine the two fields. “It was fascinating to apply my chemical knowledge to the requirements for nutrition in long-term space travel,” she adds. “But this research also has potential applications on Earth, for example, in storing nutrients for long periods under harsh, desert-like conditions.”

Visit elsevier.com to access content in physics, astronomy and more! Use discount code STC317 at checkout and save up to 30%!