Bitter taste in my mouth. Bitterness is the most sensitive of the classes of taste, many people find bitter foods to be too sharp, unpleasant and disagreeable. Common bitter foods are coffee, Swedish bitters, citrus, lemon juice, bitter lettuces such as rocket, kale, raddichio, endive and chicory.Taste changes in the mouth may not be caused by a serious problem, howeve it does warrant investigation as it may turn you off your food and take the pleasure out of eating.y diet has not changed, any ideas? Bitterness is the most sensitive of the classes of taste, many people find bitter foods to be too sharp, unpleasant and disagreeable. Common bitter foods are coffee, Swedish bitters, citrus, lemon juice, bitter lettuces such as rocket, kale, raddichio, endive and chicory.