What is how to make yeast?

Making yeast at home is a complex process prone to contamination, and commercially produced yeast is generally preferred for reliability and consistent results. However, here's some theoretical information on how it could be attempted, focusing on cultivating wild yeast from natural sources. This is not a guaranteed method and requires careful attention to hygiene to avoid harmful bacteria.

Sourcing Wild Yeast:
- Fruits: The surface of fruits like grapes, apples, and berries naturally harbors wild yeast.
- Flour: Some flours, particularly whole grain varieties, may contain wild yeast spores.
- Air: Yeast spores are present in the air.
Creating a Starter (Levain): This process, also known as propagating yeast, involves feeding the yeast with flour and water.
1. Initial Mixture: Combine equal parts flour and water in a clean jar. (e.g., 1/4 cup flour and 1/4 cup water). Use unbleached flour.
2. Feeding Schedule: Over several days, discard half of the mixture and replenish it with equal parts fresh flour and water. This is called "feeding" the starter.
3. Monitoring Activity: Look for signs of activity such as bubbling, rising, and a slightly sour aroma. This indicates that the yeast is multiplying.
4. Maintaining Hygiene: Use clean utensils and jars to minimize the risk of contamination.
Factors Affecting Yeast Growth:
- Temperature: Yeast thrives in a warm environment (around 70-75°F or 21-24°C).
- Food Supply: Yeast needs a constant supply of carbohydrates (from flour) to multiply.
- Hydration: The correct water-to-flour ratio is crucial for yeast activity.
Important Considerations:
- Contamination: Wild yeast starters are susceptible to contamination from undesirable bacteria and molds. This can result in off-flavors or even make the starter unsafe to use.
- Consistency: Wild yeast strains are less predictable than commercially produced yeast, which can affect the final product's flavor and texture.
- Safety: Always inspect your starter for any signs of unusual mold, discoloration, or foul odors. If you are unsure about its safety, discard it.