MARK DREDGE
A Brief History of Lager: 500 Years of the World’s Favourite Beer is out now from Kyle Books
Q. HOW DO WE DISTINGUISH LAGER FROM OTHER FORMS OF BEER?
A. The simple difference is that lagers and ales are made from different species of yeasts: lagers are Saccharomyces pastorianus, while ales are Saccharomyces cerevisiae. The important thing to know is that the yeasts like to work in different environments, with lagers fermenting at colder temperatures than ales. At some point, maybe 600 hundred years ago, ale yeast hybridised