Timely cane severance is the critical first step in the dry-on-vine (DOV) raisin-making process. If canes are severed too early, the berries will have insufficient soluble solids, limiting yield and grade, but if the canes are severed too late, then the grapes will not dry sufficiently. Further, grape maturity at drying may affect the sensory attributes of the raisins, and therefore consumer acceptance. Thus, production studies were conducted over three seasons to determine the relationship between grape maturity and the yield and quality of DOV raisins made from two important DOV raisin grape (Vitis vinifera L.) cultivars, Fiesta and Selma Pete. Additionally, sensory attributes, and consumer acceptance, of “B and better” raisins made from low or high maturity raisins of each cultivar were conducted in one year. There was a positive curvilinear relationship between berry soluble solids level and raisin grades, comparable to relationships established for tray-dried raisins. However, DOV raisins appeared to achieve higher quality grades than would be expected of tray-dried raisins, especially at soluble solids <18, or >20 Brix. Raisin yield, moisture content, and quality grades varied according to year and cane severance date but, in general, an acceptable balance of these variables was achieved by severing the canes at 19 Brix for Fiesta and 21 Brix for Selma Pete. However, consumer acceptance data suggested that most people prefer Selma Pete raisins and raisins from the most mature Fiesta grapes, all of which were made from grapes with >20 Brix at drying. It may be difficult to consistently achieve 20 Brix and adequate drying of Fiesta, suggesting Selma Pete is the superior variety for DOV raisin production.
- ©2012 by the American Society for Enology and Viticulture