One and the same thing pins Bulgaria on the world map of food, longevity, and microbiology. Yogurt is celebrated as the food of long life and vitality, and the key bacterium that gives it these properties is named after the country.
Of course, it had all started a lot earlier than the beginning of the 20th Century, since yogurt was known to the tribes living in Europe and Asia as far back as the 5th Century BC. But no one can establish for sure how milk was first cultured into yogurt. Speculations abound, with the discovery – at least in Bulgaria – ascribed to the Thracians or the Proto-Bulgarians. Allegedly either of these peoples found that milk preserved longer when soured than when fresh and after a few trials and errors discovered how to culture their mare milk (in the version with the Proto-Bulgarians) or sheep milk (in the Tracians' case) and get just the right acidity for a tasty, long-lasting dairy product.
Yogurt became a staple in the daily meal on the Balkan Peninsula and the area of India and Iran for centuries, without the habit catching on in western Europe. It coming into fashion there is owed to a French king – again, sources differ as to the particular person, with opinions split between Francis I and Louis XI. No matter whether it happened in the 16th or the 15th Century, the story stays the same. He suffered from severe stomach conditions which court doctors found themselves unable to cure. It was only when a doctor from the Ottoman Empire, either on his own initiative or sent by the sultan, prescribed a diet of yogurt that the French king was cured and spread the word about the miraculous food.
Whether it really happened or not, the story does contain a grain of truth – the bacteria contained in yogurt are beneficial to the digestive flora and help prevent some kinds of diarrhoea. The mechanism was examined only in 1905, when Bulgarian student of medicine in Geneva Stamen Grigorov first delved into the microbiology of the plain yogurt. He discovered a rod-like bacterium unknown yet to science. His work attracted the attention of biologist Ilya Mechnikov, who was a Nobel laureate doing research on longevity in the Pasteur Institute in Paris. Impressed by Grigorov's discovery, Mechnikov invited him to hold a lecture in the institute.
Grigorov arrived armed with a microscope and yogurt from Bulgaria for a practical demonstration. After his lecture the management of the Pasteur Institute tasked Mechnikov to confirm the discovery, which the Russian biologist took to heart. He became so convinced the properties of the bacterium – named by his assistants Bacillus bulgaricus – were responsible for the unusually long life of Bulgarian villagers and mountain dwellers that he took to eating yogurt every day in the belief that this would extend his own life. His energetic campaign to promote yogurt was responsible for its fame spreading around Europe.
The research quickly accumulated and two more bacteria were discovered to symbiotically aid the production of yogurt and its beneficial effects to the digestive tract. From Mechnikov's interest in longevity came the statistics that out of 36 countries, Bulgaria was the one with most centenarians – four to every 1,000 people. This influenced the public, whose enormous interest in the recipe of longevity now had to be satisfied. For those who wanted to culture their own yogurt, tablets were sold containing the inactive bacteria, and the lactose-intolerant could take them as well. After the first production line for yogurt was founded, its popularity quickly grew to encompass Europe and the United States.
Nowadays the possibilities are endless: yogurt with jam, biscuits, frozen fruit, muesli entices customers in supermarkets. Bulgarians remain staunch supporters of the classic, however, and take pride in the fact that "their" bacterium, now renamed to Lactobacillus delbrueckii subsp. Bulgaricus, is exported all over the world. They take their yogurt plain and quarrel over the quality of the modern product as compared to the one they remember from their childhood. In 2010 a Bulgarian State Standard was introduced for the yogurt.