The origins of yogurt are uncertain, the most ancient documents we know already mentions this food. Yogurt was probably consumed in the prehistorical age already, the practice of keeping liquids in goatskins, or other containers made of animal's skin or stomach, allowed the discovery of the simple production technique. The inventor of Yogurt probably was the milk itself. Milk left in contact with air, at a proper temperature, because of the effects of some bacteria, tend to coagulate and to ferment while being naturally transformed into yogurt. The lifestyle of ancient people, committed to sheep-farming and used to keep products in animal's skins and stomachs, favored the discovery of this new food: bacteria found in goatskins favored the fermentation of milk. There are many legends about the origin of yogurt. One of them has it the discoverer was a shepherd who, after having forgotten milk for some time in a goatskin, he found it changed into a more creamy and tasty product.

 Another legend - dated back to the eighth century - has it a Turk nomad, traveling in a mountain region between the Black Sea and Caspian Sea, was carrying a goatskin containing milk and, because of temperature and bacteria contained in the goatskin, it was transformed into a pleasing creamy beverage: yogurt. Yogurut or joggurt, which in Turk language means “thick milk”, seems to be the name from which derives the modern yogurt, in fact the origin of this name seems to be yogurut dated back, with high probability, to the eighth century. Since then yogurut, or yogur or joggurt, was consumed until the ninth century when the name changed into the term we know today: yogurt.

 The spreading of yogurt is so wide and it is not possible to tell the moment in which it began its spreading in the many countries. Yogurt is mentioned in the Bible and in the “One Thousand and One Nights” tales, it was used by Romans, Egyptians, Phoenicians and Greeks, it was used by Russian people, Hindu and Zulu. The Greek physician Galen mentions yogurt in his writings and he believes it has healing properties for stomach and liver. Western travelers were surprised by the longevity of Arab people living in the desert as well as of Bulgarian shepherds who used to eat yogurt in order to purify blood, bowel as well as for improving sleep. Even Mongols had yogurt in high esteem, they considered it indispensable for longevity, physical resistance and beauty. In India it is being used since immemorial times.

	Fresh natural Yogurt: a sound and useful food

 In order to give an example of the spreading of yogurt, here it is a list of some countries and the name with which is known: Iceland - Skyr; Japan - Yakult; Minor Asia - Leben, Laben; Scandinavia - Taette; Finland - Plimae, villi, Yugoslavia - Kysla Gravenica; Iran - Yok; Egypt - Leben, Laban; Norway - Kaelder-milk; Chile - Skuta; India - Dahi, Lassi; Burma - Tyre; South Russia - Kefir, Kuban; Central Asia - Koumiss; Angola - Kaffirs; Eastern Asia - Saya; Lapland - Taetioc; Arab countries - Leben; Hungary - Tarhò; Greece - Kajmak; Western countries - Yogurt, Yoghurt; Russia - Kumys, Kummiss.

 The first one to scientifically study yogurt seems to be Russian biologist Prof. Ilya Ilyich Metchnikov, researcher of the Pasteur Institute of Paris, who supported the idea in the colon of mammals could develop many harmful bacteria responsible for the development of grave diseases, in particular in subjects whose nutrition is rich of meat and do little physical activity. A regular consumption of yogurt prevents these diseases while keeping the bowel flora capable of preventing the formation of noxious bacteria. One of the merit of this professor was the discovery, in the yogurt common in the Bulgarian people known for their longevity, of the bacteria responsible for the fermentation and from that moment on it was called “Bulgarian” that is Lactobacillus Bulgaricus.

 Yogurt is a product obtained by the spontaneous acidification of milk. This process is conducted by mean of lactose scission - milk sugar - in two components, glucose and galactose, and the subsequent production of lactic acid. The process of fermentation is started by lactic ferments Lactobacillus Bulgaricus e Streptococcus Thermophilus. Lactic ferments are living monocellular organisms, and must be present naturally alive at least for 100 millions for each gram of yogurt and at least 10 millions at the moment of consumption. This rule is not strict but it derives by the fact lacto-bacteria, at the moment of production, begin to die up to their complete extinguishment. Yogurt keeps all the original fat part of milk whereas the proteinic part undergoes a partial hydrolyzation process which makes it more digestible, in other words, the acidification process leads to the division of the complex proteinic chains and to the “fine flocculation” of proteins, a process which ease the aggression of enzymes during digestion.

 In Yogurt, proteins of whey remain unaltered even after the fermentation, the presence of lactose and lactic acid highly favor the availability of two very important elements contained in milk: calcium and phosphor. The high acidity of yogurt helps bowel flora to contrast the many putrefactive phenomena typical of the human bowel. Moreover yogurt, by means of fermentation, gets enriched of vitamins, in particular the ones belonging to group “B”.

 The process of industrial yogurt making begins with the pasteurization of milk. This process consists in heating the milk to a temperature of at least 72°C (161°F) and for at least 15 seconds, a subsequent and quick cool down at 8-18°C (46-50°F). This process destroys every noxious bacteria and unfortunately part of vitamins and calcium contained in milk as well. Anyway it is worth doing because fresh non pasteurized milk may contain harmful bacteria, and in some cases, they can be present bacteria of typhus, diphtheria and tuberculosis. For this reason it is advisable to avoid the consumption of non pasteurized milk, even though, calcium and vitamins can also be found in other foods. The preparation procedure continues by adding lactic ferments, the fermentation of the product (3-6 hours), homogenization in order to prevent the presence of fatty globules, cooling down at 4°C (39°F), adding sugar and/or cooked fruit when needed, adding natural aromas when needed as well as preservatives such as potassium sorbate (E202), packaging and commercialization.

 A short mention about E202 “potassium sorbate” can be useful. First of all, it is a preservative that avoids the spoilage of foods, in labels is usually found with the letter “E” (European Union) followed by its identifying number. Preservatives permitted by law goes from E200 to E299. In our specific case, potassium sorbate (E202) is an anti-mold product used in cheese, yogurt, tortellini, mayonnaise, bakery products, fats and oils, with the exception of olive oil. It is a product classified as “absolutely safe”. The preparation of homemade yogurt does not differ much from the industrial process. It begins by heating the milk until ebullition, lowering and stabilization of temperature down to 40-44°C (104-111°F), adding of the lactic ferments (that could also be in the form of yogurt as well), acidification, which usually happens within 12-24 hours, cooling down to a temperature of 4°C (39°F), keeping in refrigerator. Homemade yogurt should be consumed within a week and kept in the refrigerator at a temperature from 4 and 10°C (39-50°F).

 The chemical composition of yogurt varies according to the type of milk used for its production - whole cow milk, goat, sheep or other animals - to the level of skimming and any possible adding of aromatic substances or fruit. Some components directly come from the breast or blood of the animal, therefore it is of fundamental importance the milk is from a sound animal. The pasteurization process, used in the production of industrial yogurt, prevents the presence of harmful microbes, however it does not alter any noxious substance present in the animal's body. Lactic ferments responsible for fermentation mainly are Lactobacillus Bulgaricus and Streptococcus Thermophilus. Vitamins mainly found in yogurt are A, B1, B2, B6, B12, C, D e I; the main mineral salts are calcium, phosphor, potassium and sodium.

 Yogurt made with partially skimmed cow milk contains 88.50% of water, 3.50% of proteins, 1.80% of fats, 5.00% of sugars 49 Kcal per 100 grams. Goat yogurt contains 86.30% of water, 3.90% of proteins, 4.30% of fats, 4.70% of sugars and 72 Kcal per 100 grams. Finally, sheep yogurt contains 82.70% of water, 5.30% of proteins, 6.90% of fats, 5.20% of sugars and 103 Kcal per 100 grams.

 The good properties of yogurt are now known to anyone, its particular composition makes it an ally of the digestive system thanks to its acidity, to the presence of active ferments and to the vitamins of group B. Yogurt is rich in calcium, which in the form of “calcium lactate”, helps the bowel to the assimilation of foods. Yogurt is particularly useful in the nutrition of babies and elder people as well as in case of digestion problems. Yogurt favors the synthesis of vitamins belonging to the group B, the synthesis of antibiotic substances, the deactivation of some cancerous substances, the cure for dysentery caused by bacteria, the restoration of bowel flora, the cure for constipation as well as a cure for sickness of stomach and bowel. Fats contained in yogurt are made of very small molecules, therefore easily assimilable by the organism, moreover its proteins contain essential aminoacids with anti inflammatory and immunitary properties.

 Milk occupies the third place (with about 16%) in the classification of products that can be cause of allergies, yogurt, thanks to its characteristics, occupies the sixteenth place (with about 1%). The efficiency of yogurt follows a natural “countdown”. Lactic ferments contained in yogurt tend, with time, to die and therefore yogurt progressively loses its efficiency. For this reason it is best to always buy yogurt as fresher as possible. Maybe it is because of this reason many consumers prefer making their own yogurt at home in order to always have a very fresh product.