Question

What substance is added to grapes to bring about frementation??

Answer 1

Answer: The substance added is Yeast.

Explanation: Yeast is a single celled organism which when added to any product containing sugar or fermentable sugar, converts it into ethanol and Carbon dioxide.

Ethanol is a form of alcohol. Grapes are a rich source of fermentable sugars, hence on adding yeast to it and preserving it in appropriate conditions, wine is formed.