Quick Answer
A good fermentation starter culture is a healthy, active mixture of microorganisms that rapidly converts sugars into lactic acid, producing a safe and flavorful fermented product. It should contain a balanced population of beneficial bacteria and yeast. A reliable starter culture is essential for successful fermentation.
Selecting a Starter Culture
When selecting a starter culture for fermentation, choose a product with a guaranteed viability rate of at least 80% for bacteria and 90% for yeast. Look for products with a balanced mixture of Lactobacillus and Bifidobacterium species for yogurt, kefir, or sauerkraut, or Saccharomyces cerevisiae for bread fermentation. For fermented vegetables like kimchi or sauerkraut, a starter culture with Leuconostoc and Pediococcus species is ideal.
Maintaining a Starter Culture
To maintain a healthy starter culture, store it in the refrigerator at 39°F (4°C) and feed it regularly with a small amount of sugar or vegetable juice. For yogurt and kefir cultures, add a small amount of milk or kefir every week, while for sauerkraut and kimchi cultures, feed with a small amount of vegetable juice or brine. Regularly sub-culture the starter to maintain its viability and prevent contamination.
Creating Your Own Starter Culture
You can create your own starter culture by allowing a fermentation process to continue, and then transferring a portion of the active culture to a new vessel for the next batch. This process is called “back-slopping” and is commonly used for sourdough bread, yogurt, and kefir. To create a sourdough starter, mix equal parts of flour and water and allow it to ferment at room temperature for 24-48 hours, feeding it regularly and discarding half of the starter each time.
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