The French scientist Louis Pasteur invented pasteurization to preserve wine 140 years ago. The process was first widely used to treat to milk in the USA in the 1920s.
Today, pasteurization heats milk to 161 degrees for 15 seconds, which destroys harmful bacteria without significantly changing milk’s nutritional value, according to the Food and Drug Administration.
Unpasteurized and pasteurized milk taste the same, but fresher milk is generally sweeter because bacteria combine over time with the milk sugar to form tart lactic acid, which is found in yogurt, says Marie Walsh, a food scientist at Utah State University in Logan. That could account for the common perception that raw milk is sweeter, because it’s often fresher.
In 1938, milk-borne outbreaks constituted 25% of all disease outbreaks from contaminated food and water. Today that figure is 1%, in part because of pasteurization, says Caroline Smith DeWaal, food safety director at the Center for Science in the Public Interest in Washington, D.C.
Pasteurization is “one of the most significant public health successes of all time,” says Michael Lynch, an expert in gastric diseases at the Centers for Disease Control and Prevention in Atlanta.