After Harry was accepted to Hogwarts in 1991, Hagrid was given the task of actually locating Harry, as Harry's uncle Vernon was doing everything in his power to prevent his nephew from receiving his Hogwarts acceptance letter.
Sucrose is a disaccharide that yeast cells convert to glucose for alcoholic fermentation. When the yeast cells produce CO 2, this gas is trapped in bubbles in a layer of foam. Your teacher will pass around a cup with a foam layer so you will know what it looks like.
He guessed that yeast was responsible for not just the alcohol but also the carbon dioxide that made the beer bubbly. In 1860, Louis Pasteur scientifically proved that the yeast present in wines and alcoholic beverages produced alcohol and carbon dioxide using the process called fermentation.