30 



BULLETIN 77, HAWAII EXPERIMENT STATION 



ISABELLA GRAPE 



(Vitis labrusca) 



Description: The Isabella grape, the only variety of grape grown 

 commercially in Hawaii, is an American seedling grape of the slipskin 

 type. The bunches are from 4 to 6 inches in length and very firmly 

 packed. The individual grapes are a deep purple-black with a light blue 

 bloom when ripe, and are about a half inch in diameter. 



History: Grapes, grown throughout most of the world, are of many 

 different types. They were introduced into Hawaii at an early date, as 

 Captain Vancouver speaks of leaving grape vine plants and orange 

 plants on March 4, 1792 (74, p. 46). Don Marin also speaks of his 

 vineyard in his diary in 1815 and records the making of wine (74, p. 47). 

 The grape grown by him was probably the Mission grape from Calif- 

 ornia, which has since disappeared. The date of the introduction of the 

 Isabella grape into Hawaii is not known, but must have been after 1816, 

 the date of the discovery of the Isabella as a seedling in South Carolina 

 (18, p. 310). Because it is grown largely by the Portuguese in Hawaii, 

 it is often erroneously called a Portuguese or European type of grape. 



Nutritive value: Grapes are of value in the diet largely because of 

 their distinctive flavor and refreshing qualities. Their sugar content is 

 similar to that of other fresh fruits of the same water content. 



The analyses of the Isabella variety show that the quantity of cal- 

 cium, phosphorus and iron of the seeded grapes (i.e., those with the 

 seed removed ) with the skins is higher than in those without the skins. 

 In either form the Isabella grapes are only a fair source of these three 

 minerals, though the quantities found for this variety are somewhat 

 smaller than the average quantities for grapes reported by Sherman 

 (59). 



No tests were made to determine the vitamin content of the Isabella 

 grapes, but Daniel and Munsell (9) have shown that the closely related 

 Concord grape contains very little vitamin A or B and no vitamin C or 

 G. For their experiments they used the juice and pulp of the Concord 

 grapes and suggest that possibly the skins, which were discarded, may 

 have contained some vitamins. 



However, the same authors (10) report experiments using Sultanina 

 and Malaga grapes with skins and conclude that they contain only small 

 amounts of vitamin A, fair amounts of vitamin B, little or no vitamin 

 G, and very little vitamin C. 



The conclusion that grapes of any variety contain only small or 

 negligible quantities of all the vitamins seems justifiable. 



Daniel and Munsell (10) have shown that commercial grape juice 

 contains no demonstrable quantities of any of the vitamins. 



The acids of Concord grapes have been shown (40) to consist of 

 approximately 60 percent malic acid and 40 percent tartaric acid, a large 

 portion of which exists m the form of alkali salts. Citric and malic 

 acids are well oxidized by the body (60, p. 403), but scientists do not 

 agree regarding the fate of tartaric acid in the human body. Though 



