Raisins are sweet due to their high concentration of sugars (about 30 g of fructose and 28 g of glucose in 100 g of raisins). The sugars can crystallize inside the fruit when stored after a long period, making the dry raisins gritty, but that does not affect their usability. These sugar grains can be dissolved by blanching the fruit in hot water or other liquids.
Raisins range from about 67% to 72% sugars by weight, most of which is fructose and glucose. They also contain about 3% protein and 3.5% dietary fiber. Raisins, like prunes and apricots, are also high in certain antioxidants. As with all dried fruits, raisins have a very low vitamin C content. Raisins are low in sodium and contain no cholesterol. New research has shown, despite having a high concentration of sugars, raisins fight bacteria in the mouth that cause cavities and gum disease.