Answer;
Louis Pasteur
Explanation;
He was French chemist, this man discovered that heat could kill bacteria that otherwise spoiled liquids including milk, wine, and bee.
He developed germ theory and pasteurization and also demonstrated the Germ Theory of Disease.
The germ theory was his idea that microorganisms might cause disease.
It met great resistance at first because for centuries disease was believed to be punishment for an individual's crimes or misdeeds.