A recipe for sour milk involves adding 1 tablespoon of vinegar or lemon juice to 1 cup of whole milk. Let the mixture sit for 5 minutes before using it. Sour milk is not the same thing as milk that has gone sour after spoiling.
Bakers often use sour milk as a substitute for buttermilk in recipes. Both use acidity to develop flavor. Add sour milk to balance the alkalinity of other ingredients in recipes.
One recipe that uses sour milk is banana cake. To make the recipe, dissolve baking soda in sour milk, and add it to the batter mix. Mix 1/2 cup of sugar and 1/2 cup of vegetable shortening until it is creamy. Add two separated eggs and three mashed bananas to the mix. Mix in 1 cup of sour milk, 2 1/2 cups of flour and 1/2 teaspoon of salt. Combine everything together well, then add 1 teaspoon of vanilla. Pour the batter into a round cake and bake it at 350 F for 40 minutes.
Food poisoning is caused by food that has not been kept hot or cold enough. Milk that is kept between 40 degrees and 140 degrees is more likely to cause food poisoning. Keep milk refrigerated, and do not substitute spoiled milk for sour milk.