Effect of Grape Pulp upon Soluble Solids Determinations

Abstract

The effect of grape pulp upon the accuracy of hydrometric soluble solids measurements was tested by comparing hydometer and refractometer Brix determinations of unfiltered and filtered grape juice samples. Significant discrepancies were observed in the unfiltered samples. On the average, the hydrometer gave readings from 0.4° to 0.7° Brix higher than the refractometer, after application of appropriate correction factors. On the other hand, in testing filtered juice, mean Brix values obtained by either instrument differed by less than 0.1° Brix. The effect of grape pulp and sampling upon hydrometric and refractometric Brix determinations in grape juice samples is discussed.