Louis Pasteur (1822–1895), during the 1850s and 1860s, showed that fermentation is initiated by living organisms in a series of investigations.[11] In 1857, Pasteur showed that lactic acid fermentation is caused by living organisms.[24] In 1860, he demonstrated that bacteria cause souring in milk, a process formerly thought to be merely a chemical change, and his work in identifying the role of microorganisms in food spoilage led to the process of pasteurization.[25] In 1877, working to improve the French brewing industry, Pasteur published his famous paper on fermentation, "Etudes sur la Bière", which was translated into English in 1879 as "Studies on fermentation".[26] He defined fermentation (incorrectly) as "Life without air",[27] but correctly showed that specific types of microorganisms cause specific types of fermentations and specific end-products.