The chemical breakdown of a substance by bacteria, yeast, or other microorganisms, typically involving effervescence and the giving off of heat.

शर्करा का किण्वन

English Usage: The fermentation of sugar is a crucial step in brewing beer.

Hindi Usage: शराब बनाने में शर्करा का किण्वन एक महत्वपूर्ण चरण है।