Correlation of the Force Required to Pick Rotundifolia Berries and Their Soluble Solids Content

Abstract

The force required to remove a grape berry from its pedicel by extension has been correlated with the soluble solids content of the berry. Experimental data are reported on four cultivars of V. rotundifolia (Carlos, Magnolia, Tar Heel and Noble). A total of 517 berries are in the reported sample. The force required to pluck the berry was measured with a specially designed spring balance. The soluble solids content was determined using a temperature compensated Abbe refractometer. All varieties exhibited an inverse correlation between force and soluble solid content. Using least squares fitting techniques inverse power laws were fitted to the data for Carlos and Tar Heel. Using similar techniques straight lines with negative slopes were fitted to the date for Magnolia and Noble. Implications of the results are discussed.