Flow Properties of Dulce de Leche, a Typical Argentine Dairy Product

Abstract

Dulce de Leche (caramel jam) is a typical Argentine dairy product similar in composition to sweetened condensed milk. Its flow properties were measured for solids content between 55 and 70% and temperatures between 25 and 70° C. Thixotropicity of the product was quantified using Weltmann's model and decreased with solids content. The coefficient of thixotropic breakdown was correlated with temperature for each sample to allow prediction of thixotropicity. From shear stress-shear rate flow diagrams the Herschel-Bulkley model was adequate for Dulce de Leche. Except for the most concentrated samples at low temperatures, the flow index was nearly constant with an average value of .748, thus demonstrating Dulce de Leche to be a pseudoplastic substance. Yield stress and consistency index decreased with temperature increase and increased with solids content. A single expression to predict these parameters as a function of temperature and solids could not be found due to chemical changes that occur during the cooking process. An empirical exponential expression was used to correlate consistency index and yield stress versus temperature for each sample and a similar expression to correlate these parameters versus solids content at each temperature. © 1988, American Dairy Science Association. All rights reserved.