A raisin is a dried grape. Raisins are produced in many regions of the world and may be eaten raw or used in cooking, baking and brewing. In the United Kingdom, Ireland, New Zealand and Australia the word "raisin" is reserved for the dark-coloured dried large grape, with "sultana" being a golden-coloured dried grape, and "currant" being a dried small Black Corinth grape. Golden raisins are treated with sulfur dioxide after drying to give them their golden color. Raisins are sweet due to their high concentration of sugars (about 30% fructose and 28% glucose by weight). The sugars cancrystallise 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 can contain up to 72% sugars by weight, most of which is fructose and glucose. They also contain about 3% protein and 3.7%–6.8% dietary fiber. Raisins, like prunes and apricots, are also high in certain antioxidants, but have a lower vitamin C content than fresh grapes. Raisins are low in sodium and contain no cholesterol.
Raisins are sweet due to their high concentration of sugars (about 30% fructose and 28% glucose by weight). The sugars cancrystallise 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 are produced commercially by drying harvested grape berries. In order for a grape berry to dry, water inside the grape must be removed completely from the interior of the cell onto the surface of the grape where the water droplets can evaporate. However, this diffusion process is very difficult because the grape skin contains wax in its cuticle, which prevents the water from passing through.In addition to this, the physical and chemical mechanisms located on the outer layers of the grape are adapted to prevent water loss.
Raisins can be eaten as a nutritious snack, rich in dietary fiber, carbohydrates with a low glycemic index, minerals, vitamins and other micronutrients. Their fat and cholesterol content is low. The overall nutritional value of raisins means that they are recommended as a snack for both weight control and for maintaining good human health because they help the control of glucose and cholesterol, the good functioning of the digestive system and the regulation of blood pressure. Replacing unhealthy snacks by raisins in usual and moderate quantity can improve health biomarkers in patients with controlled Type 2 Diabetes. It has been found that adoption of this dietary habit may reduce diastolic blood pressure and increase the levels of plasma antioxidants in type 2 diabetic patients. Corinthian raisins are a moderate glycemic index fruit. They can be consumed in small amounts even by diabetic patients instead of sweets in a balanced diet. Antioxidants in Greek raisins may reduce the risk for malignancies in the stomach and colon. Thus, in a balanced diet, their antioxidants can help maintain the health of the digestive system.