Conversation so far:
What is fermentation?
Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes.
How do Louis Pasteur and fermentation go together?
Pasteur motivated to investigate fermentation while working at Lille developed his ideas to establish there is an alcoholic ferment, the yeast of beer, which is found everywhere that sugar is.

Question: Did he prove his theory?
Self-contained rewrite: Did Louis Pasteur prove his theory?