Moisture-dependent physical properties of seedless and seeded raisin (Vitis vinifera L.) varieties

Abstract

Some physical properties of seedless and seeded raisin berries varieties were evaluated as a function of moisture content, varying from 16.12% to 35.63% (d.b.) for seedless berries and from 17.33 to 34.41% (d.b.) for seeded raisin berries. The average dimensions, shape, and mass of the both raisin berries increased as moisture content increased. The mass of 1000 berries increased linearly. Besides, in seedless berries, the bulk density increased, the true density and porosity decreased, while in seeded berries the bulk and true density decreased, but porosity increased. The Weibull distribution model statistically characterized raisins on the basis of berries dimensions for classifying and separating targets. The results indicate that classifying raisin berries by means of bivariate Weibull distribution in terms of the length and width is useful in describing the process under study and designing or calibrating the hole sizes of classifiers machinery.