Viscoelastic properties and compensation study of apple juice enriched with apple fiber
D.E. Salinas, Alfonso Garvín, Raquel Ibarz, Albert Ibarz
Abstract
Viscoelastic properties of an apple juice enriched with apple fiber dose (12%, 14%, 16%, 18% w/w), were evaluated in the temperature range of 5–60 °C using dynamic oscillatory viscometry. Samples at four fiber concentrations behaved like viscoelastic fluids with consistently higher magnitudes of storage modulus (G′) as compared to loss modulus (G″) in a frequency sweep. The addition of fiber increased the elastic character of the apple juice. The G′ and G″ were higher for the 18% fiber sample, and temperature had a significant effect on the dynamic rheological properties of the four samples, decreasing the magnitudes of G′ and G″ while temperature increased. The viscoelasticity was evaluated for storage and loss modulus with the oscillatory frequency described by a power-law function and the dependency of this parameter with temperature was well described by Arrhenius' type equation(k', k'', n' and n''). Compensation was found to take place for the parameters k’ and k’’, the iso-consistency temperature being −45.7 °C and −68.2 °C, respectively, showing a entropic control for the flow mechanism.