Gram flour can be used in GF recipes without bitterness being a factor if you bake the flour first. Spread 1 - 2 cups of flour on a cookie sheet and bake on medium heat for 15 minutes, stirring every 5 minutes. The first time you pull it out of the oven a strong unpleasant smell will come up. By the end of the 15 minutes, that smell will be gone and your flour is ready to cool and use. It will clump, so sift it or stir well with a fork.