Thomcord is a seedless table grape variety and a hybrid of the popular Thompson Seedless or Sultanina grape and Concord grape. Thomcord was developed in 1983 by Californian grape breeders working for the Agricultural Research Service, an agency of the United States Department of Agriculture, as part of a test to better understand a new seedless grape breeding procedure.
Its aromatic, "labrusca" flavor is similar to that of Concord, but mellowed by the mild, sweet taste from Thompson Seedless. Thomcord grows well in hot, dry climates, ripens between late July and mid-August, and tolerates powdery mildew. It is a productive variety, yielding an average of 15.1 kg of grapes per vine, but has produced as much as 30 to 32 kg per vine in grower trials. The berries weigh between 2.72 and 3.38 g and have a medium-thick, blue-black skin that adheres to the fruit, unlike Concord, which has a thick skin that can slip off the pulp easily. The aborted seeds in the fruit body are relatively small, but larger than those in Thompson Seedless.
The plant is not restricted for propagation and distribution. Virus-free propagation material is available from the Foundation Plant Services at the University of California, Davis, and its genetic material is archived at the National Plant Germplasm System. After 17 years of testing, it was declared ready for use in 2003. It is expected to appear in supermarkets, possibly as a specialty item.
In structure, each berry features semi-translucent flesh encased in a smooth, thin skin. Some varieties contain edible seeds, while others are seedless. The color to the fruit is because of the presence of poly-phenolic pigments in them. Red or purple berries are rich in anthocyanins while white-green berries contain more of tannins, especially, catechin. Interestingly, these antioxidant compounds are densely concentrated on the skin and seeds! The three main species of grapes grown around the world are; European, North American, and French hybrids.
Some of popular green cultivars are Thompson seedless, sugarone, and calmeria.
Red varieties include emperor, red globe, cardinal, and flame seedless.
Concord and zinfandel are some of flavorful blue-black cultivars.
Commercially, many cultivars of grapes are grown for different purposes either eaten as table fruit, fresh or dried (raisin, currant, sultana) or in wine production.
Grapes are rich in polyphenolic phytochemical compound resveratrol. Resveratrol is one of the powerful anti-oxidant, which has been found to play a protective role against cancers of colon and prostate, coronary heart disease, degenerative nerve disease, Alzheimer's disease and viral/ fungal infections.
Resveratrol reduces stroke risk by altering the molecular mechanisms in the blood vessels. It does so firstly by reducing susceptibility of blood vessel damage through decreased activity of angiotensin (a systemic hormone causing blood vessel constriction that would otherwise elevate blood pressure) and secondly, through increased production of the vasodilator substance, nitric oxide (a beneficial compound that causes relaxation of blood vessels).
Anthocyanins are another class of polyphenolic anti-oxidants present abundantly in the red grapes. These phyto-chemicals have been found to have an anti-allergic, anti-inflammatory, anti-microbial, as well as anti-cancer activity.
Catechins, a type of flavonoid tannin group of anti-oxidants, found in the white/green varieties have also shown to possess these health-protective functions.
In addition, the berries are very low in calories. 100 g fresh grapes just provide 69 calories but zero cholesterol levels.Grapes are rich source of micronutrient minerals like copper, iron and manganese. Copper and manganese are an essential co-factor of antioxidant enzyme, superoxide dismutase. Iron is especially concentrated more in raisins. In addition, 100 g of fresh grapes contain about 191 mg of health benefiting electrolyte, potassium.
They are an also good source of vitamin-C, vitamin A, vitamin K, carotenes, B-complex vitamins such as pyridoxine, riboflavin, and thiamin.
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