PASTEUR “then began to add a “ferment” of beer yeast to get the process going, but his ultimate goal was still to establish a neat equation that ignored the yeast and counted up the water and sugar on one side, and the alcohol and carbon dioxide on the other. The work was a failure, one of the few of his career.”
https://www.tandfonline.com/doi/full/10.1080/00026980.2020.1867786