The kinds of food the astronauts eat are not mysterious concoctions but foods prepared here on Earth, with many commercially available on grocery store shelves. Diets are designed to supply each crew member with all the recommended dietary allowances of vitamins and minerals necessary to perform in the environment of space. Foods flown in space are researched and developed in the Foods Systems Engineering Facility at NASA Johnson Space Center in Houston, Texas. Foods are tested for nutritional value, how well they freeze dry, the storage and packaging process, and of course taste. Astronauts are asked to taste test food items. They use a simple form to rate the products on such things as appearance, color, odor, flavor, and texture. These components are rated using a numbering system. The Food Systems Engineering Facility uses the astronauts ratings to help design better space food. Astronauts select their menu about 5 months before they fly. For the ISS, they choose 30-day flight menus. Crew members store the food in the galley onboard the Station. The astronauts  use a special tray on the ISS to hold their food during preparation and eating. Because everything drifts in a microgravity environment, utensils and food containers need to be held in place. Food trays will be designed on the basis of the food packages that will be used on the ISS. These trays are different from those used on the Space Shuttle because the ISS  has a table available; the Space Shuttle does not. The ISS tray attach to the table. From the beginning of human space travel, food has been an important feature that has involved astronauts, technicians, and engineers. Because food is an important part of life, it is imperative that the space food system is the best it can be. Astronauts on the ISS cannot get into a car and go down to the local grocery store if they do not like what is for dinner. The supply of food must be nourishing and tasty so astronauts maintain their health during their important stays in space.

There are eight categories of space food:

Rehydratable Food: The water is removed from rehydratable foods to make them easier to store. This process of dehydration (also known as freeze drying) is described in the earlier Gemini section. Water is replaced in the foods before they are eaten. Rehydratable items include beverages as well as food items. Hot cereal such as oatmeal is a rehydratable food.

Thermostabilized Food: Thermostabilized foods are heat processed so they can be stored at room temperature. Most of the fruits and fish (tuna fish) are thermostabilized in cans. The cans open with easy-open pull tabs similar to fruit cups that can be purchased in the local grocery store. Puddings are packaged in plastic cups.

Intermediate Moisture Food: Intermediate moisture foods are preserved by taking some water out of the product while leaving enough in to maintain the soft texture. This way, it can be eaten without any preparation. These foods include dried peaches, pears, apricots, and beef jerky.

Natural Form Food: These foods are ready to eat and are packaged in flexible pouches. Examples include nuts, granola bars, and cookies.

Irradiated Food: Beef steak and smoked turkey are the only irradiated products being used at this time. These products are cooked and packaged in flexible foil pouches and sterilized by ionizing radiation so they can be kept at room temperature. Other irradiated products are being developed for the ISS.

Frozen Food: These foods are quick frozen to prevent a buildup of large ice crystals. This maintains the original texture of the food and helps it taste fresh. Examples include quiches, casseroles, and chicken pot pie.

Fresh Food: These foods are neither processed nor artificially preserved. Examples include apples and bananas. Refrigerated Food: These foods require cold or cool temperatures to prevent spoilage. Examples include cream cheese and sour cream.

Source: Public information from NASA