When a recipe calls for mayonnaise, there is sometimes an editor’s note saying that reduced-fat or fat-free mayonnaise may not be substituted. Can whipped salad dressing be substituted for mayonnaise in those recipes? —P.S., Thief River Falls, MinnesotaWe often add such an editor’s note to recipes that are heated or baked. Our home economists have found that both reduced-fat and fat-free mayonnaise can break down when heated and leave an unpleasant texture. Also, eggs in mayonnaise may be needed for leavening in recipes for baked goods, and not all reduced-fat and fat-free mayonnaise contain eggs. If the whipped salad dressing you mention contains eggs and fat, it can be substituted in equal amounts for mayonnaise.