Germ theory of disease
Louis Pasteur showed that the germ theory of disease was true. In 1862, he invented a process that heats up a liquid to a high temperature to keep it from spoiling. This process is known as pasturization, named after Pasteur. Pasteurization is used to kill microscopic organisms in liquids like milk, wine, and beer. Liquids that are pasteurized will last much longer before they spoil.