Other than putting the jug of milk in the refrigerator immediately after I get home from the supermarket, I don’t think much about how to keep the milk clean and fresh. A hundred years ago, people worried a lot more about maintaining milk quality. Here’s what it said in a hundred-year-old home economics textbook:
There are many very important things to know about milk, but nothing is more important than to know how to care for it in the home. Because it is such a perfect food, it is a very good place for germs to grow.
Be sure to wash the bottle before pouring out any milk. Get into the habit of doing this. You do not know what kind of dirt may have come in contact with the bottle after the milk was put into it.
If milk is left in the bottle replace the cap or, better, provide a clean one. A cup or glass may be inverted over the bottle. Do not pour the milk into another utensil unless necessary. If necessary, be sure that the container is absolutely clean. Milk very readily absorbs the odors and flavors of other food in the refrigerator, and this is another good reason for covering it.
Sometimes milk is not delivered in bottles but is dipped from a can and poured into pans or pails. Be sure that the pans are scalded and kept covered until the milk id delivered. Do not put milk tickets into them, or leave them uncovered on the doorstep. If milk is bought at the grocery store one should not walk through the streets with the pail uncoverered.
As soon as the milk is delivered the bottle should be washed and put into the refrigerator. If allowed to stand in a warm room it sours very quickly.
All milk containers should be rinsed with cold water as soon as empty. They should then be washed with clean, soapy water and rinsed with scalding water. In the summer time it is a good plan to boil the pans and pails with soda water for fifteen minutes.
Household Arts for Home and School, Vol. II (1920) by Anna M. Cooley and Wilhelmina H. Spohr
[The book also contained directions for making a homemade cooler for those who did not have a refrigerator – but that is potentially another post, another day.]