salt as flavor enhancer. salt is ionic compound so it disassociates and releases flavor molecules from food.
breads are made from leaveners: yeast (microorganism), baking soda, baking powder. The yeast feed off starches (flour) producing fermentation products like acid, CO2 and ethanol (same process for beer/alcohols). baking soda or baking powder is alkaline and makes bread like biscuits through acid/base chemical reaction when adding an acids like buttermilk it produces similar products like CO2. CO2 is what makes the bread rise or add carbonation (bubbles) to champagne.