1 - Buy a lab-derived specific bacterial strain - eg. dried yeast for baking…
2 - Use the last spoonful of yogurt or piece of sourdough to start the next batch.
3 - Use a SCOBY (symbiotic culture of bacteria and yeast) to make products such as kombucha, where the scoby ferments the sweet tea to produce carbon dioxide and acetic acid - which creates a vinegary taste.
Can you ferment anything? “There is no food that cannot be fermented," said Katz.
"All of the plant and animal products that make up our food are populated by broad microbial communities. It’s the environmental conditions that determine which organisms can grow; so the practice of fermentation is largely about the manipulation of environmental conditions so as to encourage the growth of certain organisms while simultaneously discouraging the growth of others.”