One thing that was striking was that all of the astronauts that Emeril chatted with (both on the Space Station and here on terra firma) mentioned that they wanted spicy and well-seasoned dishes, because food simply doesn't have as much flavor in space. I hypothesized that for some reason your sense of smell is diminished in space, making food less tasty. Husband hypothesized that the redistribution of bodily fluids in the low gravity made the tongue swell and function differently. (They aren't great hypotheses, but heck, it was 3AM.)
First off, it turns out that we were both right and both wrong. Microgravity does indeed change the distribution of fluids and astronauts do have stuffed up nasal passages. When this hypothesis was tested in simulated microgravity here on earth, however, no change in taste was observed (PubMed abstract). Experiments on astronauts in space have been fairly consistent with those results. Other possible causes that have been proposed are that it's a side effect of space sickness, lower atmospheric pressure (which may affect the smell of foods), stress, or psychological effects of social and environmental isolation (Olabi 2002 (pdf)). Studies so far have been inconclusive, and I would bet that it turns out that the cause is a combination of different factors.
Why does this matter? I would say that it's a quality of life issue, especially for very long trips, such as the proposed manned mission to Mars. As Olabi and colleagues point out:
Eating is one of the basic needs of humans and any disturbance in the enjoyment of eating foods due to taste alterations can have an effect on the health and morale of astronauts in long term space missions, in a similar manner to what occurred with with individuals on Antarctic missions (Stuster, 1996).Interestingly, the science fiction stories I've read that deal with human adaptation to low gravity largely focus on changes to bone and muscle mass. There are descriptions of space-"evolved" humans with longer, lighter limbs and feet adapted for gripping. However, I haven't read any that discussed changes in the chemical senses*. Would space-goers be more likely to eat alien foods simply for the novelty? Would they be less able to detect contaminated or spoiled food? Would there be changes in sexual attraction?
The entire culture of a human colony living in a low gravity environment might turn out to be very different from our own here on earth. (And I'm hoping that someday the Food Network will routinely carry shows on "space cuisine" with some of the answers. )
* There is a colorful description of a zero gravity formal banquet, with "finger foods" and "toe foods" in John C. Wright's story, Guest Law.
Review Article: Olabi et al. "The Effect of Microgravity and Space Flight on the Chemical Senses" J. Food Sci 67:468-478 (2002)"> (pdf)
Tags:space, food, , physiology