What are the scientific differences between salting vegetables and macerating fruit?
Many recipes, including our Strawberry-Rhubarb Pie, call for macerating fruit before incorporating it into a dish. Like salting watery produce such as cabbage, eggplant, or zucchini, tossing fruit with sugar and leaving it to sit draws out moisture that might otherwise lead to soupy fillings with bloated (or blown-out) produce. Like salt, sugar pulls water out of cells through osmosis: It creates a higher concentration of dissolved molecules at the surface of the fruit, which in turn causes water from inside the fruit’s cell walls to be drawn out, since water has a tendency to move from a more dilute solution to a more concentrated one. But sugar and salt differ in their efficiency at the task. This is because the speed at which water is drawn out depends on the number of ions or molecules present. Sugar remains one molecule when dissolved, while salt molecules divide into two ions. So in any given solution, fewer sugar ions will be at work by volume than salt ions. But because we toss the produce with a comparatively high concentration of sugar when macerating, it still gets the job done in a reasonable amount of time.