Photo by Alecsandro Andrade de Melo

Photo by Alecsandro Andrade de Melo

Best if used by.   Use before.    Good until.

These little stamps on your dairy containers may feel like rigid expirations, but knowing how dairy changes over time will allow you to extend the use of it past the due date.

Sour cream: Sour cream sweetens when it ages. It actually transforms into regular ol’ cream cheese. At my store, sour cream is half the price of cream cheese, so I end up planning ahead and refrigerating the sour cream past expiration. It’s not so great for spur-of-the-moment cheesecake, but if you are a regular baker or just like your morning bagel, it’s a great way to have sour cream for stroganoff and cream cheese for later.

Yogurt: We’ve all opened an old yogurt container and found the top covered with a light yellow liquid. A lot of people assume the yogurt is expired. Mais non! As yogurt ages, the live cultures continue to multiply. These cultures make yogurt more sour, and the liquid that rises is actually whey that separates as the yogurt settles. Draining whey out of fresh yogurt is how companies make the thick European yogurt, often called “Greek yogurt.”

Pour off the liquid (or feed it to your chickens/hog in their feed), and use it for waffles or baking; the sour is an acid that will react with baking soda to make your batter rise. Sour cream coffee cake has a great flavor when sharp yogurt is substituted for the sour cream — which you’ll be aging for your bagels, right?

Milk: Ah, sour milk. Great to replace buttermilk in most recipes, and used in quick breads to react with the baking soda and make everything rise. There are recipes online for a multitude of foods that use sour milk, from pancakes to breaded chicken to cookies. Cook anything that has added sour milk.

Be sure to know the difference between sour and spoiled. Taste it to learn the flavor, as unpleasant as that may be.

In general, milk starts to sour within 6 days of the Use By date. However, this is not conclusive; there are many reasons milk can sour earlier. Use all dairy products before they thicken, curdle, and become discolored. Unless you have introduced special bacteria (cultures) to make cheese, the curdled dairy is not considered safe for human consumption.

As always, keep your dairy products refrigerated in the safety zone (lower than 43 degrees Fahrenheit) until ready to use, and never use anything that smells rancid or has discoloration. It is okay to warm the dairy in the microwave or on the stove just before adding it to breads.

If you have any favorite recipes for sour milk or yogurt, please share them in the comments below!