Kitchen Mysteries is a weekly exploration of oddities surrounding cooking and food. They could be recipes that fail when they shouldn't, conflicting advice from different sources, or just plain weirdness. If it happens in a kitchen, and you're not sure why, send a tweet to The Food Geek to find out what's happening.
Meg Maker asks via Twitter:
Not a dumb question at all. The simple answer is that the pasta is safe because it is dry. When we think of egg danger, we think of salmonella. Salmonella is a bacteria, and like all living organisms, they need three things to thrive: food, water, and shelter.
It's usually the "shelter" aspect that we think of when we're fighting bacteria in the kitchen nowadays. Ever since we had the ability to refrigerate and freeze food throughout the year and at will, that's been our go-to method for controlling the possibilities of food contamination. After all, we put it in a box, and suddenly the bacteria drops below 40°F, the lower end of the "bacterial danger zone" that allows bacteria freedom to replicate as quickly as they want.
At the upper end of the temperature scale, we've been cooking our food for just about forever now, but aside from that, Louis Pasteur's process of heating food to kill off the bacteria has shaped our world-view on how we like to preserve food: kill all the bacteria, then refrigerate the rest to slow any additional bacteria. In other words, make the environment as hostile to the bacteria as possible, or remove their shelter.
Still, this is not the only way to combat bacteria, and aside from cooking food in general, those techniques are relatively new as far as food preservation goes.
You can't really remove food from the bacteria's diet, as they generally eat what we eat, or at least some of what we eat. So the only thing that's left is taking away bacteria's water, and that's what most of food preservation has been throughout our history.
In the case of meats, including fish, people would remove the bacteria's ability to thrive by salting the meat. With a high enough concentration of salt, bacteria can't absorb the water in the food. Instead, the water is drawn out of their system, because the cellular structure of the bacteria (and most everything else) tries to maintain a balance of water to salt ratios on each side of the cell walls. If one side becomes out of balance, water travels through to the other side until equilibrium is reached, or until someone runs out of water. In these cases, the bacteria will run out of water pretty quickly.
For some fruits, meats, and our egg pasta, another option is to just dry the food. Remove the water from the food, and the bacteria has nothing to drink. It's not as sexy as salting the food, but it is remarkably effective in its simplicity. And that, the long way around, is why it's okay to dry and store egg pasta.