Maintaining the Texture of Cooked Beans

Three substances slow the softening of beans and therefore make it possible for the cook to simmer beans for hours or reheat them without disintegrating them. Acids make the cell-wall pectins and hemicelluloses more stable and less dissolvable; sugar helps reinforce cell-wall structure and slows the swelling of the starch granules; and calcium cross-links and reinforces cell-wall pectins. So such ingredients as molasses—somewhat acid and rich in both sugar and calcium—and acidic tomatoes can preserve bean structure during long cooking or reheating, as for example in baked beans.