Uses of Bacteria in Yogurt

Bacteria turns milk into yogurt through fermentation. The live bacteria in yogurt, in turn, provide benefits to the people who eat it. Most yogurt-making begins with heating milk, then adding two friendly bacteria: streptoccus thermophilus and Lactobacillus bulgaricus or even just one, the Lactobacillus acidophilus bacteria. Those bacteria begin fermenting the milk by using the milk sugar, or lactose, for their energy source. In the process of doing that, the bacteria produce acids, which is what gives yogurt its distinctive taste.

History

• Cherries, or other fruit or flavors, change yogurt's traditionally sour taste.

  The creation of lactic acid during the fermentation process is what gives yogurt its sour taste. There is speculation that the first yogurt was created by accident when milk was left in the sun, perhaps in a goat-skin bag, and fermented. Far from being spoiled, the resulting product was a tasty food. The lactic acid in yogurt improves its microbiological stability and the safety of the product.

  Humans probably began making and eating yogurt as early as 2500 B.C. Yogurt was found mostly in India, Asia and southern and central Europe until recent times. Yogurt wasn't commercially produced until the 20th century. The addition of fruit and various flavors changed the traditionally sour taste, and yogurt became more popular. But while some people eat yogurt now for the flavor, other people are interested in the potential health benefits of consuming live, beneficial bacteria.

Process

• Yogurt is made by heating milk, then adding live bacteria.

  Streptoccus thermophilus, Lactobacillus bulgaricus and Lactobacillus acidophilus are all living bacteria. These bacteria do the work of turning milk into yogurt by fermenting the milk and producing acids in the process.

  "The acids they produce as end products of their metabolism (waste) curdle the milk protein and also give the sour taste to the yogurt," a molecular biologist, who was identified as vanhoeck, wrote in an article on the Newton website of the Argonne National Laboratory.

Bacteria

• Some people believe that eating yogurt has health benefits.

  The acids created by the friendly bacteria fermenting the milk help to curb the growth of unfriendly bacteria in the yogurt. In addition, molecular biologists say that those friendly bacteria continue to be alive in the yogurt. The intestines of healthy mammals have friendly, or probiotic bacteria, such as the live bacteria found in yogurt. And many people believe that consuming yogurt, with live, friendly bacteria, has health benefits.

Yogurt

• Many people think there are health benefits from consuming yogurt and some studies back that up.

  "Yogurt, defined as the product of milk fermentation by Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, has a long history of beneficial impact on the well-being of humans," wrote the authors of a study titled "Survival of Yogurt Bacteria in the Human Gut," published in the American Society of Microbiology. In that study, using commercial yogurt, the researchers found evidence that the live, beneficial bacteria in yogurt did survive in people's intestinal systems. So consuming yogurt could help people.

  Some people say eating yogurt with live cultures promotes the growth of friendly bacteria in the colon, thereby helping to improve the immune system, prevent disease and support the proper functioning of the digestive system. Some medical professionals use yogurt to control antibiotic-related, or bacterial, diarrhea, or to restore balance after a round of antibiotics kills some of the friendly bacteria in the digestive tract. Eating yogurt also can help lactose-intolerant people digest milk. To get those benefits, look for the words "live and active cultures" on the yogurt label.