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Yogurt: the story on HearLore | HearLore
Yogurt
The first yogurt was likely created by chance, not design, when milk stored in animal skin bags exposed to wild bacteria began to ferment in the warm climates of Central Asia and Mesopotamia around 5000 BC. Neolithic people domesticating milk-producing animals stumbled upon this transformation, discovering that the milk had thickened and acquired a tart flavor that preserved it longer than fresh milk. This spontaneous fermentation occurred independently across many regions, with the earliest evidence suggesting that the bacteria responsible, Lactobacillus delbrueckii subsp. bulgaricus, may have originated on plant surfaces before transferring to milk through contact with udders or the environment. The process relied on the natural acidity produced by these bacteria, which acted on milk proteins to create a gel-like structure that could survive in harsh conditions where fresh milk would spoil quickly. Ancient cultures, from the barbarous nations described by Pliny the Elder to the nomadic Turks of the 11th century, utilized this thickened milk as a staple food, often consuming it with honey or as a base for soups and stews. The word itself, derived from the Turkish verb meaning to knead or thicken, reflects the physical transformation of the liquid into a solid, a change that was once a mystery to those who first encountered it.
The Science of Survival
In 1905, a Bulgarian medical student named Stamen Grigorov made a discovery that would change the global understanding of yogurt, identifying the specific bacteria responsible for its fermentation. He observed that the milk contained two distinct types of lactic acid-producing bacteria: a spherical form and a rod-like form, the latter of which was later named Bacillus bulgaricus, now known as Lactobacillus delbrueckii subsp. bulgaricus. This finding caught the attention of Ilya Mechnikov, a Russian biologist and Nobel laureate at the Institut Pasteur in Paris, who hypothesized that the long lifespans of Bulgarian peasants were directly linked to their regular consumption of yogurt. Mechnikov believed that these bacteria were essential for good health and worked tirelessly to popularize yogurt throughout Europe, transforming it from a regional staple into a global health food. The science behind yogurt production involves maintaining a warm temperature between 40 and 45 degrees Celsius for 4 to 12 hours, allowing the bacteria to convert milk sugars into lactic acid. This acidification process not only gives yogurt its characteristic tart flavor but also creates a barrier against pathogens, ensuring the safety of the product. The bacterial culture is mixed into the milk, and the resulting fermentation process is a delicate balance of time, temperature, and bacterial activity that determines the final texture and flavor of the product.
Common questions
When was the first yogurt created and where did it originate?
The first yogurt was likely created around 5000 BC in the warm climates of Central Asia and Mesopotamia. This spontaneous fermentation occurred when milk stored in animal skin bags was exposed to wild bacteria.
Who discovered the specific bacteria responsible for yogurt fermentation in 1905?
A Bulgarian medical student named Stamen Grigorov discovered the specific bacteria responsible for yogurt fermentation in 1905. He identified two distinct types of lactic acid-producing bacteria, including the rod-like form later named Bacillus bulgaricus.
When did Isaac Carasso start the Danone yogurt company in Barcelona?
Isaac Carasso started a small business in Barcelona, Spain, in 1919 and named his company Danone after his son Daniel. This innovation allowed yogurt to be produced on an industrial scale for a wider audience.
What are the health benefits of consuming yogurt according to recent studies?
Studies suggest that consuming yogurt may improve lactose tolerance and digestion while reducing the risk of type 2 diabetes. A 2021 review found a cause-and-effect relationship between yogurt consumption and improved lactose tolerance as well as potential associations with improved bone health.
How does the texture of yogurt change based on the type of milk used?
Goat milk yogurt has a low viscosity and a thinner texture when compared to cow milk yogurt. Sheep milk has a higher content of solids which results in a higher viscosity and thicker texture.
When did the European Union rule that the word yogurt is reserved for products of animal origin?
The European Union ruled in 2017 that the word yogurt is reserved for products of animal origin only. This ruling followed regulation 1308/2013 which restricts the use of the term for plant-based alternatives.
The transformation of yogurt from a local delicacy to a global commodity began in 1919 when Isaac Carasso started a small business in Barcelona, Spain, naming his company Danone after his son, Daniel. Carasso's innovation was to produce yogurt on an industrial scale, making it accessible to a wider audience beyond the traditional regions of Central Asia and the Balkans. The brand later expanded to the United States under the Americanized name Dannon, marking the beginning of yogurt's journey into the American mainstream. In 1933, the Radlická Mlékárna dairy in Prague patented yogurt with added fruit jam, introducing the concept of flavored yogurt to the market. The introduction of yogurt to the United States in the first decade of the 20th century was influenced by Élie Metchnikoff's The Prolongation of Life, which promoted yogurt as a health food. John Harvey Kellogg, a physician at the Battle Creek Sanitarium, used yogurt both orally and in enemas, further promoting its health benefits. In 1929, Armenian immigrants Sarkis and Rose Colombosian started Colombo and Sons Creamery in Andover, Massachusetts, delivering yogurt in a horse-drawn wagon inscribed with the Armenian word madzoon, which was later changed to yogurt, the Turkish name. The company's success led to the introduction of fruit-on-the-bottom yogurt in 1966, which became a massive commercial success, with sales exceeding $1 million per year by the late 20th century. The brand was eventually sold to General Mills in 1993 and discontinued in 2010, but its legacy remains in the modern yogurt industry.
The Global Table
Yogurt has become a cornerstone of culinary traditions across the globe, with each region developing its own unique varieties and preparations. In the Indian subcontinent, dahi is a yogurt known for its characteristic taste and consistency, often used in Hindu rituals as one of the five elixirs, or panchamrita. Sweetened dahi, known as mishti doi, is common in eastern India, made by fermenting sweetened milk. In West Sumatra, dadiah is a traditional yogurt made from water buffalo milk and fermented in bamboo tubes, while in Nepal, yogurt is served as both an appetizer and dessert, playing a central role in festivals, marriage ceremonies, and religious occasions. The city of Bhaktapur is famous for juju dhau, a local yogurt that is a staple of Nepali culture. In Tibet, yak milk is used to make yogurt, butter, and cheese, while in Northern Iran, Mâst Chekide is a variety of kefir yogurt with a distinct sour taste, often mixed with a pesto-like water and fresh herb purée called delal. In Greece, tzatziki is a thick yogurt-based salad made with cucumber, olive oil, and garlic, serving as a popular accompaniment to gyros and souvlaki. In the Middle East, labneh is a strained yogurt with a consistency between that of yogurt and cheese, often used in sandwiches or as a stuffing for pies. These regional variations highlight the versatility of yogurt, which can be transformed into soups, desserts, sauces, and beverages, depending on the local ingredients and cultural preferences.
The Health Debate
The health benefits of yogurt have been a subject of intense scientific scrutiny, with studies suggesting that consuming yogurt may improve lactose tolerance and digestion, reduce the risk of type 2 diabetes, and lower the incidence of hip fractures in post-menopausal women. A 2011 review found that high-quality clinical evidence was insufficient to conclude that consuming yogurt lowers the risk of diseases, but meta-analyses have shown that consuming 80 grams per day of low-fat yogurt is associated with a lower risk of developing type 2 diabetes. A 2021 review found a cause-and-effect relationship between yogurt consumption and improved lactose tolerance, as well as potential associations with improved bone health and reduced risk of some diseases, including cancers and metabolic syndrome. The European Food Safety Authority determined in 2010 that lactose intolerance can be alleviated by ingesting live yogurt cultures, enabling manufacturers to use health claims on product labels. However, the safety of yogurt made with raw milk remains a concern, as it can be contaminated with bacteria such as Listeria, Cryptosporidium, and Salmonella, which can cause significant illness and even result in death. The acidity of yogurt provides a barrier against pathogens, but recent outbreaks of food poisoning by acid-tolerant E. coli O157:H7 have raised questions about the effectiveness of this barrier. Despite these concerns, yogurt remains a popular health food, with many commercial products supplemented with extra probiotic bacteria to enhance their health benefits.
The Science of Texture
The texture of yogurt is a complex interplay of physics and chemistry, characterized as a viscous, shear-thinning, non-Newtonian fluid that forms when milk is fermented. The microstructure of yogurt is affected by both the fat and protein content and the processing conditions, with low-fat formulations creating a network of casein protein globules joined via clusters and strands that encapsulate pores. Stirred yogurt formulations have a coarser distribution of loosely associated casein particulates due to the shear forces and resulting particle-particle collisions induced during the mixing process. The mechanical properties of yogurt are typically assessed using rheometry, which quantifies the deformation and flow response of soft materials subject to shear forces. These properties are dictated by a variety of processing factors, including the ratios of dry and wet matter, thermal treatments, milk origin, starter cultures, and yogurt type. Goat milk yogurt has a low viscosity and a thinner texture when compared to cow milk yogurt, while sheep milk, having higher content of solids, has a higher viscosity and thicker texture. The process of straining yogurt removes the whey, giving it a much thicker consistency, and can be done at home using a filter made of muslin or paper. Strained yogurt, known as labneh in Middle Eastern countries, has a consistency between that of yogurt and cheese, and can be used for sandwiches or as a stuffing for pies. The rheology of yogurt is a fascinating area of study, revealing the intricate relationship between the physical properties of the product and the methods used to produce it.
The Future of Fermentation
The yogurt industry is evolving rapidly, with the emergence of plant-based alternatives using soy milk, rice milk, and nut milks such as almond milk and coconut milk. These products, fermented with cultures, offer a suitable alternative for people with lactose intolerance and those who prefer plant-based foods, such as vegetarians and vegans. However, plant-based milks have different structures and components than dairy milk, and some consumers may feel that they lack the delicate and smooth structure of conventional yogurts. Since plant-based milks do not contain lactose, the food of Streptococcus thermophilus and Lactobacillus bulgaricus, plant-based products usually contain different bacterial strains, such as Lactobacillus casei and Bifidobacterium bifidum. In Europe, companies may not market their plant-based products using the word yogurt, as that term is reserved for products of animal origin only, per European Union regulation 1308/2013 and a 2017 ruling in the Court of Justice of the European Union. The US FDA's Standard of Identity regulations also reserve the word yogurt for a product made from lactation. Despite these challenges, the yogurt industry continues to innovate, with new flavors and textures being developed to meet the demands of a changing consumer base. The future of yogurt lies in its ability to adapt to new dietary preferences while maintaining its core identity as a fermented milk product.