How was the cause of disease discovered?
It was a commonly believed notion that germs generated spontaneously. Nobody knew what exactly caused a disease. It was only in 1860s that a French chemist, Louis Pasteur began experimenting with bacteria. In one of these experiments he proved that germs can be generated in a controlled environment too. He showed that food went off because of contamination by microbes in the air. He went on to argue that these could cause diseases. His discovery of the cause of disease led to development of antiseptics and changed healthcare forever.
How do you kill germs in food and drink?
Louis Pasteur invented a process to kill germs, which went on to be called Pasteurization.
Due to the urban growth caused by industrialization, the period between production and consumption of milk increased widely. This became one of the crucial source of diseases like tuberculosis. It was the process of pasteurization which finally helped milk to be one of the safest foods.
How is milk pasteurized?
When milk is heated to 72 °C (161 °F) for 15 seconds, it causes the germs in the milk to stop functioning without affecting the nutritional value of the milk.