Recipe Talk

Hi.
I have a recipe for creme fraiche and it calls for heavy cream that is NOT ultra pasteurized. I have yet to find that. Do you think using ultra pasteurized will affect the outcome of the recipe? If so, where do you think I might find some?
Thank you.
Carrie alias Jane Wayne

créme fraîche (creme fraiche) Pronunciation: CREM FRESH Notes: This slightly sour thick cream doesn't curdle when it's heated, so it's ideal for making cream sauces. It's also used for appetizers and as a dessert topping. To make your own: Warm one cup heavy cream to about 100degrees, then add one or two tablespoons of sour cream, cultured buttermilk, or plain yogurt (make sure you buy a brand that contains active cultures). Allow the mixture to sit at room temperature for at least nine hours before refrigerating. Substitutes: crema Mexicana OR equal parts sour cream and heavy cream OR clabber cream (thicker consistency) OR sour cream (This has a lower fat content, and so it's more likely to curdle if boiled with an acidic ingredient.) OR yogurt (This will definitely curdle when boiled.)