Most food will not keep fresh for very long _____(1)_____. Fish and meat will quickly go bad and start to smell. Fruit and vegetable will soon rot. This spoilage is caused by chemical changes in the food _____(2)_____ very tiny organisms. These micro-organisms such as yeasts, moulds and bacteria are in the air all around us, and they may grow on all kinds of foods. _____(3)_____ cause food to give off smelly gases, to ferment _____(4)_____. Some bacteria produce substances _____(5)_____. _____(6)_____, we must somehow prevent all these things from taking place, or at least _____(7)_____. Canning is the most important method of food preservation, and it can be used for practically all kinds of foods. _____(8)_____, the food is sealed in airtight cans and heated strongly. _____(9)_____ by the heat. The ones outside can’t get in _____(10)_____calmly