On Food and Cooking

powered farm machinery meant that cattle
could be bred and raised for milk production
alone, not for a compromise between milk and
hauling, so milk production boomed, and
more than ever was drunk fresh. With the
invention of machines for milking, cream
separation, and churning, dairying gradually
moved out the hands of milkmaids and off the
farms, which increasingly supplied milk to
factories for mass production of cream, butter,
and cheese.
From the end of the 19th century, chemical
and biological innovations have helped make
dairy products at once more hygienic, more
predictable, and more uniform. The great
French chemist Louis Pasteur inspired two
fundamental changes in dairy practice:
pasteurization, the pathogen-killing heat
treatment that bears his name; and the use of
standard, purified microbial cultures to make
cheeses and other fermented foods. Most
traditional cattle breeds have been abandoned