How is yogurt made? How does yogurt get its flavor? A special combination of cooking techniques and bacteria species (that’s right!) goes into making yogurt. Milk is the main ingredient in yogurt. People who make yogurt take milk and heat it to about 200 degrees Fahrenheit (93 degree Celsius). They leave the milk at this high temperature for 10 to 30 minutes. The longer they heat the milk, the thicker the yogurt will be. After heating the milk, they quickly reduce the temperature to about 112 degrees (44 degrees Celsius). Next comes the bacteria! This might sound gross, but these kinds of bacteria are not the kinds that make you sick. The bacteria used in yogurt actually give it a tangy flavor. The species of bacteria used in yogurt are Streptococcus thermophilus and Lactobacillus bulgaricus. These species eat the sugars in milk. As the bacteria eat milk sugars, the bacteria produce something called lactic acid. Lactic acid makes milk proteins curdle. Thanks to the bacteria, the milk becomes thick yogurt. The lactic acid also gives yogurt a tart, tangy flavor. As an added bonus, most harmful bacteria can’t survive around high levels of lactic acid. That means the bacteria that give yogurt its tangy flavor can also keep yogurt safe to eat. Some kinds of yogurt contain probiotics. Probiotics are tiny organisms, like bacteria, that live inside humans and keep humans healthy. In the human digestive system, probiotics help break down nutrients and ward away harmful bacteria. Once the milk is mixed with the bacteria, it is stored in clean containers and left to incubate for at least four hours. If the milk and bacteria incubate for more than four hours, the yogurt will have a more tart flavor. Yogurt producers can change the flavor by adding ingredients like fruits and flavor extracts like vanilla or lemon. Yogurt can be a healthy part of the diet. It contains proteins to help you build muscles. Yogurt also contains a vitamin called B12. This vitamin keeps your red blood cells and your nervous system healthy. Though most yogurt in the United States is made with cow’s milk, some people make yogurt with milk from goats, camels, yaks or water buffalo.