For separation by separating from

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PROCEEDINGS OF THE TUTOR STUDENTI.IT for conservation is a set of possible processes which maintain solid nutritional characteristics, physico-chemical, hygienic and organoleptic characteristics of the food for a longer or shorter time than the fresh product. The conservation has historically been done by man, because it allowed to consume some foods abundant in some seasons, in others they were not present; is still the case of canned vegetables or tomato sauce. The global markets food cans have made it increasingly important extension food cans of the storage of food, because food often make long journeys before reaching the final consumer; This led to the emergence of new and more effective methods of prolonging storage, hand in hand with new scientific discoveries and new consumer needs. food cans
Chemical methods allow the lowering of the pH of the food, so the innalazamento of its acidity, or the reduction of 'free water, which is not chemically bound to other compounds. These two factors are effective in conservation because they reduce two of the key factors in the degradation of the food; or water, fundamental matrix for the life of the majority of microorganisms food cans and enzymatic food cans processes naturally active in the food, and the acidity, as some micro-organisms can not survive at pH lower than 4.5. The acidification is carried out by means of preservatives which may be synthetic (citric acid, ascorbic acid, ...) or natural; the latter being used at household level, food cans such as lemon juice or vinegar. The reduction of water occurs instead by sequestering substances, namely that attract water outside dell'alimenti, such as salt and sugar, which are essential to combat microbial contamination because many microorganisms malsopportono high concentrations of salt or sugar.
Biological processes are among the oldest, allow to prolong the durability of a food without adding foreign substances to the food itself, and the second a spontaneous process a load of microorganisms naturally present in some foods. Biological process for excellence is fermentation which allows the reduction of oxygen, acidification over which the production of aromatic substances food cans pleasing taste and smell; This is the case with many cheeses, yogurt, olives in brine, and many meats.
For separation by separating from 'food possible pathogens and / or spoilage. This is the case of microfiltration performed on the milk using filters with very small holes capable of separating the microorganisms from the rest of the product. These methods often are joined by heat treatment because not entirely effective.
For change of state of water: They are methods using low or high temperatures for the elimination of 'water that we have said to be essential to the survival of microorganisms. Among these include: drying, which allows evaporation of water using high temperatures; and freeze-drying which provides first freezing the water and then the sublimation of the same directly to steam using low temperatures and low pressures, food cans since at low pressures the water evaporates at a lower temperature.
To change the temperature: Among those are the most used physical damage as the most effective results without vary greatly organoleptic and nutritional characteristics of 'food. Can be distinguished food cans in the heat treatment and cold treatments. The first involving the killing of microorganisms, most of which do not survive at temperatures above 67 C in the vegetative food cans form, in order of increasing temperature are: Pasteurization, Blanching or scalding, baking and sterilization. Those cold instead of allowing only slow down the activity of microorganisms without killing food cans them, in order of decreasing temperature are: refrigeration, freezing and freezing.
In this group also includes special methods that use ionizing radiation (gamma, ics and microwave) food cans but used only for certain products because they are more expensive that allow you to heat the water without food deterioration.
Finally, there are other chemical and physical treatments now much less used, or mostly in local products. food cans An example is the smoking which allows using the p