Explanation

Louis Pasteur observed that yeast cells grew rapidly in air but used little sugar and produced little carbon dioxide and ethanol. Under anaerobic conditions, they grew slower but used more sugar and produced more carbon dioxide and ethanol. This phenomenon of inhibition of breakdown of carbohydrate and production of ethanol is known as Pasteur effect. Biochemically, Pasteur effect is an Allosteric inhibition of phosphofructokinase enzyme in the presence of oxygen.