food preservation usually involves preventing the growth of bacteria, fungi (such as yeasts), or other micro-organisms (although some methods work by introducing benign bacteria or fungi to the food), as well as retarding the oxidation of fats that cause rancidity. food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation. many processes designed to preserve food will involve a number of food preservation methods. preserving fruit by turning it into jam, for example, involves boiling (to reduce the fruitâs moisture content and to kill bacteria, etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar (to prevent recontamination). some traditional methods of preserving food have been shown to have a lower energy input and carbon footprint, when compared to modern methods."preserving food without freezing or canning, chelsea green publishing, 1999" maintaining or creating nutritional value, texture and flavor is an important aspect of food preservation, although, historically, some methods drastically altered the character of the food being preserved. in many cases these changes have come to be seen as desirable qualities â cheese, yogurt and pickled onions being common examples. == traditional techniques == techniques of food preservation are available to the home chef, ranging from since the dawn of agriculture up until the industrial revolution. === drying ===  drying is one of the oldest techniques used to hamper the decomposition of food products. as early as 12,000 b.c., middle eastern and oriental cultures were drying foods using the power of the sun. vegetables and fruit are naturally dried by the sun and wind, but in the middle ages, "still houses" were built in areas that did not have enough sunlight to dry things. a fire would be built inside the building to provide the heat to dry the various fruits, vegetables, and herbs.nummer, b. (2002). âhistorical origins of food preservationâ http://nchfp.uga.edu/publications/nchfp/factsheets/food_pres_hist.html. (accessed on may 5, 2014) === refrigeration ===  refrigeration preserves foods by slowing down the growth and reproduction of micro-organisms and the action of enzymes that cause food to rot. the introduction of commercial and domestic refrigerators drastically improved the diets of many in the western world by allowing foods such as fresh fruit, salads, and dairy products to be stored safely for longer periods, particularly during warm weather. === freezing === thumb|right|pictorial guide inside a freezer door {{main|froze
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