Bacteria turn milk into yogurt through a process called fermentation, where they consume lactose and produce lactic acid.
The Yogurt-Making Process Explained
Here's a breakdown of how bacteria transform milk into the creamy, tangy treat we know as yogurt:
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Bacteria Culture: Yogurt production relies on specific types of bacteria, primarily Streptococcus thermophilus and Lactobacillus bulgaricus. These bacteria are added to milk.
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Lactose Fermentation: The bacteria consume the lactose, the natural sugar found in milk.
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Lactic Acid Production: As the bacteria metabolize lactose, they produce lactic acid as a byproduct.
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pH Reduction: The increased lactic acid content lowers the pH of the milk, making it more acidic.
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Protein Coagulation: The acidic environment causes the milk proteins (primarily casein) to unfold and clump together, a process called coagulation. This is what thickens the milk and gives yogurt its characteristic texture.
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Flavor Development: The lactic acid contributes to the tangy flavor of yogurt. Other byproducts of fermentation, such as acetaldehyde, also play a role in the final flavor profile.
In summary, bacteria ferment the milk sugar lactose into lactic acid. The lactic acid then causes the milk proteins to coagulate, creating yogurt.
