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Rheology of dairy custard model systems: Influence of milk -fat and hydrocolloid type

F. Vélez-Ruiz, Jorge, González-Tomás, Luis, Costell, Elvira
European food research & technology 2005 v.221 no.3-4 pp. 342-347
custards, hydrocolloids, lambda-carrageenan, pasting properties, rheology, shear stress, skim milk, starch, temperature, viscoelasticity, viscosity, whole milk, xanthan gum
The influence of milk-fat content and the addition of two types of hydrocolloid (λ-carrageenan and a mixture of λ-carrageenan and xanthan gum) on the pasting behaviour, the flow and the viscoelasticity of custard model systems with modified tapioca starch at different concentrations was studied. To evaluate the pasting behaviour, apparent viscosity and temperature data were recorded over time. Flow was measured by recording shear stress at shear rates from 1 to 200 s⁻¹and vice versa and viscoelasticity by performing the frequency sweeps from 0.01 to 1 Hz. Substitution of skim milk by whole milk increased apparent viscosity values during pasting. All the samples exhibited time dependence and pseudoplastic behaviour. Shear stress values increased when skim milk was substituted by whole milk, except for the custard system with 6% of starch. G′, G″ and η* values at 1 Hz resulted higher for whole milk systems although differences relatively decreased with starch concentration. The effect of hydrocolloid type was not significant (α=0.05) for all the parameters studied except for the n values.