Yoghurt (yogurt AmE), less commonly yoghourt, joghurt or yogourt, is a dairy product produced by bacterial fermentation of milk. Any sort of milk may be used to make yoghurt, but modern production is dominated by cow's milk. It is the fermentation of milk sugar (lactose) into lactic acid that gives yoghurt its gel-like texture and characteristic tang. It is often sold in a fruit, vanilla, or chocolate flavour, but can also be unflavoured.



History

There is evidence of cultured milk products being produced as food for at least 4,500 years, since the 3rd millennium BC. The Bulgars (also Hunno-Bulgars), a Turkic-speaking people from Aryian-Pamirian origin, migrated into Europe starting from the 2nd century AD, eventually settling on the Balkans by the end of the 7th century AD. The earliest yoghurts were probably spontaneously fermented, perhaps by wild bacteria residing inside goat skin bags used for transportation.

Yoghurt remained primarily a food of India, Central Asia, Western Asia, South Eastern Europe and Central Europe until the 1900s, when a Russian biologist named Ilya Ilyich Mechnikov theorized that heavy consumption of yoghurt was responsible for the unusually long lifespans of Bulgarian peasants. Believing Lactobacillus to be essential for good health, Mechnikov worked to popularize yoghurt as a foodstuff throughout Europe. It fell to a Spanish entrepreneur named Isaac Carasso to industrialise the production of yoghurt. In 1919 he started a commercial yoghurt plant in Barcelona, naming the business Danone after his son ? better known in the United States as 'Dannon'.

Yoghurt with added fruit marmalade was invented (and patented) in 1933 in dairy Radlick? Ml'k'rna in Prague. The original intention of this combination was to protect yoghurt better against decay.

Yoghurt was first commercially produced and sold in the United States in 1929 by Armenian immigrants, Rose and Sarkis Colombosian, whose family business later became Colombo Yogurt.

Contents

Yoghurt making involves the introduction of specific "friendly" bacteria into milk under controlled (very carefully in industrial settings) temperature and environmental conditions. The bacteria ingest the natural milk sugars and release lactic acid as a waste product; the increased acidity, in turn, causes the milk proteins to tangle into a solid mass, (curd, denature). The increased acidity (pH=4'5) also prevents the proliferation of other potentially pathogenic bacteria. To be named yoghurt, the product should at least contain the bacteria Streptococcus salivarius ssp thermophilus and Lactobacillus bulgaricus (official name Lactobacillus delbrueckii ssp. bulgaricus). Often these are co-cultured with other lactic acid bacteria for either taste or health effects (probiotics). These include L. acidophilus, Lactobacillus casei and Bifidobacterium species.

In most countries a product may only be called yoghurt if there are live bacteria present in the final product. Pasteurized products (which have no living bacteria) are named fermented milk (drink).

In the US non-pasteurized yoghurt is sold as containing "live active culture" (or just as "live" ), which some believe to be nutritionally superior. In Spain, the yoghurt producers were divided among those who wanted to reserve the name yogurt for live yoghurt and those who wanted to include pasteurised yoghurt under that label (mostly the Pascual Hermanos group). Pasteurized yoghurt has a shelf life of months and does not require refrigeration. Both sides submitted scientific studies claiming differences or lack thereof between both varieties. Eventually the Spanish government allowed the label yogur pasteurizado instead of the former postre l'cteo ("dairy dessert").

Because live yoghurt culture contains enzymes that break down lactose, some individuals who are otherwise lactose intolerant find that they can enjoy yoghurt without ill effects. Nutritionally, yoghurt is rich in protein as well as several B vitamins and essential minerals, and it is as low or high in fat as the milk it is made from.

Non-sweetened drinkable yoghurt is typically sold in the West under the name "(cultured) buttermilk." This term is a misnomer, as the drink has little in common with "true" buttermilk and is, in fact, most similar to kefir.

Presentation

Yoghurt is often sold sweetened and flavoured, or with added fruit on the bottom (sometimes referred to as fruit bottom), to offset its natural sourness. If the fruit is already stirred into the yoghurt, it is sometimes referred to as Swiss-style. Most yoghurt in the United States has pectin or gelatin added. Some specialty yoghurts have a layer of fermented fat at the top similar to cream cheese (e.g. brands like Brown Cow Yoghurt). Fruit jam is used instead of raw fruit pieces in the case of fruit yoghurts so that they can be stored for weeks.