The best title for this selection is ______. [br] [originaltext] Do you kno

Do you know how astronauts act while whirling through space? Their food comes in plastic tubes, and they eat it from the tubes. Why? Spacecraft food must be light and easy to store. It must also be non-spoilable. Many of the foods made for eating in a spaceship have been a success. In fact, everyone may soon be able to have them!
     Scientists have learned to keep some foods from spoiling by removing the oxygen from them. This is done by pumping nitrogen gas into them, forcing nearly all the oxygen out. Without oxygen, bacteria cannot grow, nor can the foods spoil.
     (12[D])Freeze-drying is another way to keep food from spoiling. First the foods are frozen. Then they are dried. Fruits, vegetables, meat, and even ice cream can be freeze-dried. Years later, you can just add milk or water, and they’re ready to be eaten. And freeze-dried foods need no refrigeration!
     (13[A])Besides non-spoilable foods, scientists can now make foods from non-food materials. Coal, gas, and other nonfoods have been turned into foods. By treating these materials with bacteria, scientists can produce rich proteins.
     Experts say that four out of five of the world’s people do not eat enough protein. Man-made proteins could help people in needy areas. But it should be a long time before we sit clown to a bowl of coal and a glass of gas.