I'm in a part of Mexico that doesn't appear to use whipped cream. My wife bought some heavy cream to use for her fresh strawberry pie, added some sugar and vanilla and proceeded to whip the dickens out of it. I swear we would have turned it into butter if we kept after it! No amount of whipping would incorporate enough air to thicken it. What is the trick? The cream is pasteurized, and I never noticed in the states if it was or not. Never had a problem before. Any tips?