Yogurt manufacturing is similar to the production of ice cream. Yogurt starts out as raw milk provided by goats, cows, ewes, camels, or buffalo. It is shipped on a truck to a production facility, and stored in tanks, silos, and other chambers. The milk is then broken down by centrifugation to separate milk from fat. Centrifugation is when force from a rotating, circular motion breaks down sedimentation. The particles of fat inside milk are small, at a molecular level, and are tough to break apart without a machines help. The milk is then tested to ensure it contains the correct fat to liquid ratio. Finally it moves on to pasteurization and homogenization.
The pasteurization and homogenization processing of yogurt is similar to ice cream production. The milk for the yogurt is heated to high temperatures. Pasteurization is used to kill unwanted bacteria to make it safe to eat. Homogenization is the process of high pressure air being injected into the milk or yogurt. The homogenizer is like a piston and raises up and down to break apart the liquid and to make sure it has a smooth and flowing consistency.
Bacteria is added to the smooth and creamy base to give yogurt a flavorful taste. This is the distinct tanginess tasted in yogurt. The bacteria will not make a person sick. The bacteria feeds on the sugars (lactose) in the milk and produce lactic acid. The acid makes the milk curdle and the yogurt becomes thick. More bacteria called probiotics can be added to help maintain and fortify the digestive system.
The yogurt is then placed into a receptacle and gestated for a minimum of four hours. The longer the yogurt sits the more tart it becomes. Depending on the fermentation temperature and incubation period of the yogurt, the product will have different consistency, texture, and taste. Once the product reaches the proper fermentation time it is packaged and then shipped to the consumer.