Superfruit: Grape

A grape is a non-climacteric fruit that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, and grape seed oil. Grapes are also used in some kinds of confectionery.

Grapes grow in clusters of 6 to 300, and can be crimson, black, dark blue, yellow, green and pink. "White" grapes are actually green in color, and are evolutionarily derived from the purple grape. Mutations in two regulatory genes of white grapes turn off production of anthocyanins which are responsible for the color of purple grapes. Anthocyanins and other pigment chemicals of the larger family of polyphenols in purple grapes are responsible for the varying shades of purple in red wines.

Raisins, currants and sultanas

In most of Europe, dried grapes are referred to as "raisins" or the local equivalent. In the UK, three different varieties are recognized, forcing the EU to use the term "Dried vine fruit" in official documents. A raisin is any dried grape. While raisin is a French loanword, the word in French refers to the fresh fruit; grappe (from which the English grape is derived) refers to the bunch (as in une grappe de raisins).

A currant is a dried Zante Black Corinth grape, the name being a corruption of the French raisin de Corinthe (Corinth grape). Currant has also come to refer to the blackcurrant and redcurrant, two berries unrelated to grapes. A sultana was originally a raisin made from a specific type of grape of Turkish origin, but the word is now applied to raisins made from common grapes and chemically treated to resemble the traditional sultana.

Resveratrol

Grape phytochemicals such as resveratrol (a polyphenol antioxidant), have been positively linked to inhibiting any cancer, heart disease, degenerative nerve disease, viral infections and mechanisms of Alzheimer's disease. Protection of the genome through antioxidant actions may be a general function of resveratrol. In laboratory studies, resveratrol bears a significant transcriptional overlap with the beneficial effects of calorie restriction in heart, skeletal muscle and brain. Both dietary interventions inhibit gene expression associated with heart and skeletal muscle aging, and prevent age-related heart failure.

Resveratrol is the subject of several human clinical trials, among which the most advanced is a one year dietary regimen in a Phase III study of elderly patients with Alzheimer's disease. Synthesized by many plants, resveratrol apparently serves antifungal and other defensive properties. Dietary resveratrol has been shown to modulate the metabolism of lipids and to inhibit oxidation of low-density lipoproteins and aggregation of platelets.

Resveratrol is found in wide amounts among grape varieties, primarily in their skins and seeds which, in muscadine grapes, have about one hundred times higher concentration than pulp. Fresh grape skin contains about 50 to 100 micrograms of resveratrol per gram.

Seed constituents

Since the 1980s, biochemical and medical studies have demonstrated significant antioxidant properties of grape seed oligomeric proanthocyanidins. Together with tannins, polyphenols and polyunsaturated fatty acids, these seed constituents display inhibitory activities against several experimental disease models, including cancer, heart failure and other disorders of oxidative stress.

Grape seed oil from crushed seeds is used in cosmeceuticals and skincare products for many perceived health benefits. Grape seed oil is notable for its high contents of tocopherols (vitamin E), phytosterols, and polyunsaturated fatty acids such as linoleic acid, oleic acid and alpha-linolenic acid.

Concord grape juice

Commercial juice products from Concord grapes have been applied in medical research studies, showing potential benefits against the onset stage of cancer, platelet aggregation and other risk factors of atherosclerosis, loss of physical performance and mental acuity during aging and hypertension in humans.

Nutrients and phytochemicals

Grapes, purple or green : Nutritional value per 100 g (3.5 oz)

Energy 288 kJ (69 kcal) | Carbohydrates 18.1 g

Sugars 15.48 g | Dietary fiber 0.9 g

Fat 0.16 g | Protein 0.72 g

Thiamine (Vit. B₁) 0.069 mg (5%)

Riboflavin (Vit. B₂) 0.07 mg (5%)

Niacin (Vit. B₃) 0.188 mg (1%)

Pantothenic acid (B₅) 0.05 mg (1%)

Vitamin B₆ 0.086 mg (7%) | Folate (Vit. B₉) 2 μg (1%)

Vitamin C 10.8 mg (18%) | Vitamin K 22 μg (21%)

Calcium 10 mg (1%) | Iron 0.36 mg (3%)

Magnesium 7 mg (2%) | Manganese 0.071 mg (4%)

Phosphorus 20 mg (3%) | Potassium 191 mg (4%)

Sodium 3.02 mg (0%) | Zinc 0.07 mg (1%)

Percentages are relative to US recommendations for adults.
Source: USDA Nutrient database

Source, Images: http://en.wikipedia.org/wiki/Grape