Adding Whipped Cream, Sour Cream, Yogurt, or Fresh Cheese

For a lighter effect, hot emulsified egg yolk sauces can be finished with sour cream, yogurt, or fresh cheese in the same way that a classic sauce mousseline is finished with whipped cream. Use these ingredients sparingly, however. Yogurt and sour cream will give an unpleasant acidity to the sauce if too much is used. Fresh cheese will give delicacy and lightness to a sauce, but again, be careful not to use too much, or the sauce will have a fine graininess or a chalky texture. Keep in mind also that any of these ingredients may separate in the sauce. To prevent this, blend 1% lambda carrageenan into the cheese, yogurt, or sour cream before whisking them into the sauce.