EFFECT OF COMPOSITION ON THE RHEOLOGICAL PROPERTIES OF TOMATO THIN PULP

The shear stress versus shear rate data for different tomato thin pulp samples were a function of their compositional constituents, particul arly pectin, water-insoluble solids and total solids. The water-solubl e solids such as fructose and glucose affected the consistency of the serum fraction, but they were less important than insoluble solids. In how studies, all the samples required a certain amount of yield stres s before flow could occur. The Herschel-Bulkley model was found to be most suitable to fit the shear stress versus shear rate data for thin pulp samples with different composition. The yield stress value calcul ated from Herschel-Bulkley was a function of insoluble solids and coul d be related by an empirical equation [sigma(o) = a exp(b.(IS)], where sigma(o) = yield stress, Pa; a, b = constants; IS = insoluble solids, %. Copyright (C) 1996 Published by Elsevier Science Ltd on behalf of the Canadian Institute of Food Science and Technology