Cooling and pasteurization are critical aspects of milk quality and safety, and because of strict sanitary control points from farm to table milk is rarely in the news as a food that causes health concerns, explained Alvaro Garcia, SDSU Extension Dairy Specialist.
"Two aspects of milk handling which have been critical for food safety are milk cooling and pasteurization," he said.
Garcia shared some history to further explain the point.
"Before the 1880s, no farm in the U.S. had access to electricity, and until the 1930s very few were able to incorporate it," Garcia said.
He added that it was well-known that milk had to be kept cool for it to be preserved adequately; but without refrigeration, many small farmsteads cooled milk by placing the container in the cellar, lowering the milk bucket into the well or storing it in metal milk storage cans placed in cold water.
Then in 1935, President Roosevelt established the Rural Electrification Administration to help farmers meet the growing demand for electricity.
"Rural electrification and increased availability of motor vehicles after the First World War encouraged bulk transport of milk to minimize inefficient handling," Garcia said.
He added that by the 1950's, bulk storage tanks began replacing milk cans for on-farm storage and allowed farmers to cool their milk while awaiting pickup by a larger milk truck.
While cooling is important, Garcia quickly pointed out, alone it does not guarantee a safe product.
"Bacteria in cooled milk are "dormant" and waiting for the right conditions to proliferate," he said. "They need warm temperatures and food to "wake up" and grow, both of which they find in warm milk and inside the human body. Healthy humans can fight them off to a certain extent; on the other hand not so much children, the elderly and those with compromised immunity."
A little more history
In the 1800's raw milk was responsible for 25 percent of all foodborne outbreaks in the U.S. In 1892, German immigrant's Nathan Straus and his wife Sara privately funded the Pasteurized Milk Laboratory in New York to offer safe pasteurized milk to combat infant mortality. In 1903 child mortality was 15 percent across the U.S. whereas in New York it had already dropped to 7 percent by early 1900.
Straus was the leading proponent of pasteurization which at the time helped eliminate hundreds of thousands of deaths per year due to milk-borne illnesses.
"Generations have passed since milk was responsible for the majority of foodborne illnesses. We have lost the collective memory of what it meant to our grandparents," Garcia said. "Nowadays we almost take milk safety for granted."