All types of cream can curdle when they go bad, although you will first probably notice a sour odor. Cream is the high-fat product that rises to the top of non-homogenized milk. It comes in numerous grades, such as light cream, table cream, whipping cream or heavy whipping cream, differentiated by the amount of fat they contain. Light cream contains between 18 and 30 percent fat, light whipping cream contains between 30 and 36 percent fat and heavy cream must contain at least 36 percent fat.
The shelf life of cream depends on many factors, such as how it was processed and packaged, how the processor or grocer stored it and even on the type of cream. When stored in a refrigerator at 40 degrees Fahrenheit or below, light cream and half-and-half stay fresh for about 7 days past the expiration date printed on the package. Heavy cream stays fresh for about two to three weeks past the expiration date. These numbers apply only to unopened packages. Once you have opened the cream, use it within one to five days.
Dairy products are notorious for curdling, although cream is more stable than low-fat milk. Casein is a protein found in milk and cream, and casein molecules have a negative charge, which repels other protein molecules so the molecules do not clump together. However, when milk or cream becomes acidic, the negative charge becomes neutralized and the casein molecules stick together, causing the milk or cream to curdle. Sometimes, curdling occurs because you have added an acid, such as lemon juice or wine, to the cream. It can also occur when you cook milk or cream at high temperatures. Another reason for curdling, though, is that the cream has spoiled.
Before you dump the cream down the drain, look for other signs of spoilage. Cream occasionally contains small lumps of butter, which are not the same as curdling. These lumps do not affect the quality of the cream and you can strain them with a strainer or you can melt them by cooking them. If cream is curdled, the lumps will have a watery appearance. You will also notice a sour smell and an off taste, according to Clemson University Cooperative Extension
Opening a package of curdled cream is disappointing, but careful storage can usually prevent this. Check the expiration date before you buy cream to make sure it is fresh. Go directly home after shopping and avoid running multiple errands while you have groceries in the car. Refrigerate the cream promptly and keep the fridge at 40 degrees Fahrenheit. Store the cream inside the refrigerator, rather than in the door, which tends to remain slightly warmer, and use it by the expiration date. If cream goes bad before the expiration date, then it was not processed properly, and you should return it to the store for a refund.