Jelly molecules that are made of sugars, bond together in big and tangled molecules. These multiple sugar units give it the firm appearance. Pectins, the building material for giving shape and strength to the plant cell walls, contains several different kinds of sugar. While making jelly, as the temperature rises, the pectins leave the cell walls and get dissolved in water. As the temperature drops, pectins stop bouncing around and lose their rigidity. With enough sugar in the water, pectins firm up. As a result, a firm gel is produced that can be poked, jiggled and squished with the fingers.
Why does jelly feel so squishy?
