University of California

The relation of maturity of the grapes to the yield, composition, and quality of raisins


H. E. Jacob

Author Affiliations

H. E. Jacob was Associate in Viticulture and Associate in the Experiment Station.

Publication Information

Hilgardia 14(6):321-345. DOI:10.3733/hilg.v14n06p321. February 1942.

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That the maturity of grapes is related to the yield and quality of the raisins made from them has probably been observed almost as long as grapes have been dried to preserve them. Apparently, however, no one attempted to determine precisely the nature and magnitude of these relationships before the work done by (Bioletti (1915)),3 which was begun about 1913. Important contributions have since been made by (Lyon (1920), (1924), (Cruess and Christie (1921)), and (Nichols and Christie (1930)).

(Bioletti (1915)) reports on tests made with Muscat of Alexandria and Sultanina (Thompson Seedless) at Kearney Park, near Fresno, and at Davis, during the seasons of 1913 and 1914. With Muscat, the drying ratios reported ranged from 4.8 for grapes of 18° Balling to 3.1 for grapes of 28° Balling. Quality, as measured by the size of the individual raisins, improved notably as maturity advanced. With Sultanina, the drying ratios ranged from 4.6 for grapes of 20° Balling to 3.6 for grapes of 24° Balling. According to Bioletti’s calculations, the average increase in crop per Balling’ degree of sugar in the grapes was about 5.35 per cent with Muscat and 7.4 per cent with Sultanina. In another paper (Bioletti (1919)) briefly reported, collectively, on the results of several years’ tests on the drying of eleven varieties of grapes. He interpreted his results as showing an average increase of 35 pounds of dried grapes per ton of fresh for each added degree of sugar. Actually, his figures show the increase to range from 16 to 104 pounds, the greater increases being obtained from the riper fruit.

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Jacob H. 1942. The relation of maturity of the grapes to the yield, composition, and quality of raisins. Hilgardia 14(6):321-345. DOI:10.3733/hilg.v14n06p321
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