INTEC   05402
INSTITUTO DE DESARROLLO TECNOLOGICO PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
artículos
Título:
Rheological behavior of concentrated skim milk dispersions as affected by physicochemical conditions: change in pH and CaCl2 addition
Autor/es:
OLIVARES M.L.; ACHKAR, N.P.; ZORRILLA S.E.
Revista:
DAIRY SCIENCE & TECHNOLOGY
Editorial:
EDP SCIENCES S A
Referencias:
Lugar: Paris; Año: 2016 vol. 96 p. 525 - 538
ISSN:
1958-5586
Resumen:
Understandingthe behavior of casein micelles (CM) in concentrated regimes is critical forthe design of dairy unit operations such as drying or evaporation but also it isstill scarce. In this work, the effect of the decrease in pH and the additionof a calcium salt on concentrated skim milk dispersions was examined byrheometric measurements at 25°C. Control samples (S1), samples with a pH of 5.8(S2) and samples with 0.04 M CaCl2 addition (S3) at differentconcentrations (40, 45, 48, 50, and 52% w/w) were analyzed through flow curvesand oscillatory dynamic data by frequency sweep tests. All samples showed aclear shear thinning non-Newtonian behavior and a large dependence onconcentration, dispersions being more fluid for samples S2 and S3. A viscositymodel for microgels was used to obtain parameters related to the characteristicstructure of systems. It was demonstrated that CM had similar structure for thedifferent physicochemical systems studied and that the decrease of pH and theaddition of salt reduced the dispersion stability due to electrostatic andsteric potential energy is depleted. Dynamic data showed that dispersions atthe highest concentration had dominant and similar elastic behavior and weakgel character. A transition regime from fluid to gel was observed in samples S2at 45% w/w. None samples obeyed Cox-Merz rule. This study allowed gaining moreunderstanding related to the structure of CM systems studied.