Astronauts usually have 4 meals and consume 3200 calories per day! What do they feed them, given long duration of space mission? How do they cook in a zero-gravity? In space it’s impossible to make some decent meal. We know that astronauts eat food in tubes which is the main, but not the only dishes they have in space.
Astronauts also eat sublimated foods. Since almost every fresh or prepared product can be sublimated, astronauts can enjoy a various menu including 250 items. Among them you can definitely find dairy and meat products, fish, soups, fruit, vegetables and berries, with the only exceptions of pickles and chocolate. They are packed and delivered to astronauts as they are due to the fact that the process of sublimation of them is still under development.
Meal process in space goes by a special scenario. First, packed foods are placed in special unit that fills them with water. Then astronauts stretch the package in their hands, cut it and squeeze the food out.
Space food packs are filled with nitrogen gas that keeps it fresh without fridge. When opened, nitrogen evaporates from the pack and it only takes some warm or hot water to make food edible.