PHYSICOCHEMICAL AND RHEOLOGICAL CHARACTERIZATION OF “DULCE DE LECHE”
Natalia Ranalli, Silvina Cecilia Andrés, Alicia Califano
Journal of Texture Studies
Abstract
ABSTRACT Physicochemical and rheological characterization of “dulce de leche,” a milk‐based sauce especially popular in South America, was carried out on different types of commercial products (traditional, confectionery, reduced calories or reduced fat). Proximal composition, solid content, water activity, pH and color (Minolta Co., Ramsey, NJ) were evaluated. A controlled stress rheometer (Haake RS600; ThermoGap, Karlsruhe, Germany) was used to perform flow curves, dynamic oscillatory test in the linear viscoelastic range and creep‐recovery experiments. Although in all samples, η decreased with increasing γ ′, corresponding to shear‐thinning behavior, clear differences were found in the rheological characteristics of different types of products. Experimental dynamic data were successfully modeled using the Baumgärtel–Schausberger–Winter equation to predict the mechanical relaxation spectrum. Satisfactory prediction of other mechanical properties was validated using creep experiments. PRACTICAL APPLICATIONS In spite of the differences in composition and rheological behavior of the several types of “dulce de leche” studied, it was possible to analyze the rheological characteristics of all systems and model the obtained results using the broadened Baumgärtel–Schausberger–Winter (BSW) model as a representation of the relaxation spectra to convert dynamic data into time domain. The parameters of the BSW model were used to explain structural characteristics of the systems; thus, the overall microstructural pattern of “dulce de leche” might be similar, and the differences observed would be mainly explained by the level of interactions among macromolecular components. Using the discrete spectrum obtained from the BSW model, it was possible to calculate other viscoelastic properties of interest; thus, the proposed methodology is a useful tool, especially for establishing a rheological data bank and analyzing viscoelastic experiments of this type of product.