Louis Pasteur was a French chemist and microbiologist who is credited for discovering the principles of vaccination, fermentation and pasteurization. He is best known for inventing pasteurization, which was first used to prevent alcohol from going sour.
Pasteur, who is considered the father of microbiology, was the first scientist to prove that infectious diseases are caused by micro-organisms. This became the foundation for germ theory. Pasteur also found out that germs are contagious and encouraged doctors to sanitize their hands before surgery. Pasteur's understanding of microbes led to the creation of pasteurization, which was important, since many French families depended on wine exports. Pasteur discovered that heating wine kills most microbes without changing the wine's flavor. Chilling the wine prevents any remaining microbes from multiplying.