Dried beans and dried fruits have been heated or left in the sun to desiccate them. When you reconstitute them by cooking them or just soaking them in water, they swell up because their cells are absorbing the liquid.Drying ProcessFresh beans and fresh fruits are made dry by leaving them in the sun or baking them at high temperatures. Both methods extract water.OsmosisAny time water leaves or enters a cell through semi-permeable membranes, the process is called osmosis. When beans are dried, the water leaves the cells.SoakingSoaking beans or fruits will make the osmosis work in the opposite direction. Water molecules will enter into the cells of the fruit or beans.SwellingThe more water molecules enter into a cell, the more the cell will puff up. This is why beans and pieces of dried fruit swell when placed in water.Soaking or Cooking in Other LiquidsYou can soak or cook beans in tomato sauce or broth and soak dried fruits in syrups or juice.