Low-fat yogurt is primarily made using skimmed milk. This contrasts with whole milk yogurt, which uses full-fat milk. The process involves several key steps:
The Yogurt-Making Process:
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Milk Selection: The foundation of low-fat yogurt is skimmed milk, which has had most of its fat removed.
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Pasteurization: The skimmed milk undergoes pasteurization to eliminate harmful bacteria. This high-heat treatment ensures safety.
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Fermentation: Live and active yogurt cultures (typically Lactobacillus bulgaricus and Streptococcus thermophilus) are added to the pasteurized skimmed milk. These bacteria ferment the lactose (milk sugar), converting it into lactic acid. This process thickens the milk and gives yogurt its characteristic tangy flavor.
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Incubation: The inoculated milk is then incubated at a controlled temperature (typically around 45°C or 113°F) for several hours, allowing the bacteria to multiply and ferment the lactose.
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Cooling: Once the desired acidity and thickness are achieved, the yogurt is cooled to stop the fermentation process.
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Packaging: The finished yogurt is then packaged and often undergoes further processing, such as homogenization or the addition of fruit, sweeteners, or other flavorings.
Long-Life Yogurt: A Note on Pasteurization
It's important to note that some long-life yogurts undergo a further pasteurization step after fermentation. While this extends the shelf life, it unfortunately also kills off some of the beneficial live and active cultures.
In summary: The key difference between low-fat and whole milk yogurt lies in the starting ingredient – skimmed milk versus whole milk. The remaining steps of pasteurization, fermentation, incubation, cooling, and packaging are largely the same.
