What seems like a simple step—adding cream to simmering tomatoes for a rosy-hued pasta sauce or finishing chicken paprikash with a swirl of sour cream—can be an exercise in frustration when the dairy product separates or curdles instead of making a silky emulsion. Luckily, taking a few precautions and choosing the right cream can prevent your sauce from breaking.
It's important to keep the heat very low when you add cream, and to do it at the end of cooking. "You basically just want to warm the cream and blend," dave_c says; you don't need to bring it to a boil. It will also be less likely to curdle if it's not cold, so instead of using it straight from the fridge, let cream come up to room temperature, or stir in a bit of hot water to temper it before adding it to the pot. Mixing cornstarch into sour cream before incorporating it into dishes will prevent the sauce from breaking as well, monavano says.
Fat content also affects how dairy products behave when heated. While it may be tempting to save a few calories by using half-and-half or other lower-fat products, full-fat cream is more stable when added to hot foods. Another alternative is to use crème fraîche, which is "more forgiving and won't curdle," eclecticsynergy says.
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