Yogurt is produced in special factories around the world. Milk solids are added to the cow's milk to give it a custard like thickness. Then a mixture containing special bacteria is poured into the milk. Pictures of this lactic acid bacteria can be found below. The mixture is raised in temperature to about 110 degrees Fahrenheit, or 43 degrees Celsius, for approximately five hours.

L. Bulgarius

The bacteria acts like a yeast: as the milk heats, a substance called curd forms. Curd is resembles the hard chunks which appear in milk after the expiration date. The yogurt is then slowly cooled and possibly fruits are added. Below is some pictures of the fruit found within a sample of strawberry yogurt. The pictures in the center and the left have measurement bars marking 100 and 25 micrometers, respectively. It is amazing to see the individual cells from this fruit specimen!

Yogurt has been made for thousands of years, although the process of making it was not as refined as it is today. A good page on the history of yogurt is provided by http://www.yaourt.org. One day someone explored the possibility of using bacteria to create different types of food. Don't be alarmed though about the bacteria in yogurt. Everyone has bacteria inside their bodies; especially in the stomach and intestines where food is broke up and digested. When you eat yogurt, it encourages the good types of bacteria to multiply in your digestive track. These "friendly" bacteria also protect our system against harmful microorganisms which cause tummy aches and infection. An animated view of the bacteria contained in yogurt is shown below.

Yogurt is awesome food! It's good and good for you!

Minnesota Microscopy Society Web Pages maintained by Stuart McKernan
Comments, additions or questions may be addressed to MMS Webmaster

Questions? ... Comments? ...Short debates? ... email John Slanina, Project Micro Undergraduate Assistant
Last Updated: 7/10/98