Yes, you need yogurt to make yogurt. It's analogous to needing a starter for sourdough bread.
To understand why, consider the basic process of making yogurt: you're essentially creating an environment where specific types of bacteria can thrive and multiply, converting lactose (milk sugar) into lactic acid. This process thickens the milk and gives yogurt its characteristic tangy flavor.
Here's a breakdown:
- Milk: Provides the food (lactose) for the bacteria.
- Yogurt (Starter): This introduces the necessary bacteria cultures, typically Streptococcus thermophilus and Lactobacillus bulgaricus. These bacteria are crucial for the fermentation process.
Without introducing these bacteria, the milk will simply spoil due to the growth of undesirable microorganisms. A "starter" yogurt provides a controlled and abundant source of the beneficial bacteria, ensuring a consistent and safe fermentation.
So, while it may seem redundant, the initial yogurt acts as a "seed" to grow more yogurt. The bacteria present in the yogurt multiply in the new batch of milk, leading to the desired result.
