How to Use Xylitol and Erythritol in baking
I got my information about these products from the Emerald Forest site. They state that Xylitol or Erythritol can be used one to one in any recipe requiring sugar. Erythritol isn't quite as sweet as sugar so you might want to add a little extra.
Xylitol and Erythritol don't caramelize when used in baking so your baked goods may feel dryer then normal so the best solution is to add more liquid, lecithin, butter/margarine or even xanthan gum to the recipe to maintain moisture. They suggests sifting the xanthan gum with the xylitol or erythritol prior to adding them to the liquid ingredients. Solid chocolates and some recipes that are exposed to the air for long periods of time such as jams and jellies will also show signs of recrystallizing.
If a recipe calls for powdered or confectioner's sugar such as in cake frosting's place the dry xylitol or erythritol in a blender or food processor and pulse until you have a fine powder. You can also add some sort of starch to it since that is what is in confectioner's sugar. Two tablespoons of starch (cornstarch or arrowroot starch) to one cup of powdered sweetener. You can also use a pinch of guar gum to the powdered sweetener as well, then blend together.
When making say frosting's use two parts by weight of powder to one part shortening or butter.
To substitute for one cup brown sugar, use 1/4 cup molasses and 3/4 cup xylitol or erythritol.
REMEMBER: SUGAR ALCOHOLS (xylitol and erythritol) DO NOT REACT WITH YEAST SO IT WON'T HELP RISE BREAD, BEST TO USE ANOTHER SWEETENER LIKE HONEY OR EVEN A LITTLE RAW CANE SUGAR INSTEAD.