Define the Food System in space?

Mercury (1961-1963) astronauts had to eat bite-sized cubes, freeze dried powders, and semi liquids stuffed in aluminium tubes. For most asbonauts, the foods were unappetizing and squeezing the tubes was disliked. Moreover, it was difficult to rehydrate freeze-dried foods and crumbs had to be prevented.  Further, during the Gemini missions (1964-1967), eating improved somewhat. The first things to go were the squeeze tubes. Bite-sized cubes were coated with gelatine to reduce crumbling, and the freeze-dried foods were encased in a special plastic container to make reconstituting easier. With improved packaging came improved food quality and menus. Gemini astronauts had food choices as shrimp cocktail, chicken and vegetables, butterscotch pudding, and apple sauce, and crew was able to select meal combinations. By the time of the Apollo programme (1968-19721, the quality and variety of food increased. Apollo astronauts were the first to have hot water, which made rehydration of foods easier and improved the taste of food. Astronauts were also first to use the "spoon bowl," a plastic container that could be opened and its contents eaten with a spoon.

The task of eating in space improved to a great extent in Skylab (1973-1974). Unlike previous space vehicles for astronauts, Skylab featured a large interior area where space was available for a dining room and a table. Eating for Skylab's three-member teams was a fairly normal operation: footholds allowed them to situate themselves around the table and "sit" to eat. Added to the conventional knife, fork and spoon, was a pair of scissors for cutting open plastic seals. Because Skylab was relatively large and had ample storage area, it could feature an extensive menu: 72 different food items. It had a freezer and a refrigerator also.

Shuttle (198lonwards) astronauts have a variety of food items to choose from. They may eat from a standard menu designed around a typical Shuttle mission of 7 days, or may substitute items to accommodate their own tastes. Astronauts can design their own menus. But a dietitian has to ensure balanced supply of nutrients from these astronaut-designed menus.
The standard Shuttle menu repeats after 7 days. It supplies each member with three balanced meals plus snacks. Each astronaut's food is stored aboard the Shuttle and is identified by a coloured dot affixed to each package.

On the Space Shuttle, food is prepared at a galley installed on the orbiter's rnid-deck. The galley is a modular unit that contains a water dispenser and an oven. The water dispenser is used for rehydrating foods and the galley oven is available for warming foods.
Conventional eating utensils are used in space. Astronauts use knife, fork and spoon. The only unusual eating utensil is pair of scissors used for cutting opens the packages. Following the meal, food containers are discarded in the trash compartment below the mid-deck floor. Eating utensils and food trays are cleaned at the hygiene station with premoistened towelettes. Shuttle food system functions well in space. It consists of familiar, appetizing, well- accepted food items that can be prepared quickly and easily. A full meal for a crew of four can be set up in about 5 minutes. Reconstituting and heating the food takes an additional 20 to 30 minutes about the time it takes to fix a snack at home, and far less than it takes to cook a complete meal.