Search

Gums or hydrocolloids are important ingredients in the food industry due to their use as thickeners, stabilizers, gelling agents and texture enhancers in the foods in which they are used. In this study, gums rheological behaviors from seeds of flamboyant (Delonix regia), pixoy (Guazuma ulmifolia), and leucaena (Leucaena leucocephala) at several concentrations were evaluated. The flow and viscoelasticity curves of dispersions in water at 0.5, 1.0 and 1.5% were determined and adjusted to different mathematical models. In the three gums, at low concentrations the best behavior adjustment was obtained with the power law model, while at high concentrations the rheological behavior was adjusted to the Cross model. Viscosity decreased with increasing shear rate and flow index values (n) indicated a shear thinning behavior (n <1) for all concentrations evaluated. The values of the consistency index (K) were higher for the dispersions of the pixoy gum (0.71-1.79) than for the other gums (0.10-0.61) in all concentrations studied. The elastic modulus was greater than modulus viscous and both moduli were little dependent on the frequency in the range studied to pixoy gum, associated with gel type behavior, while flamboyant and leucaena had a macromolecular solution behavior type. [ABSTRACT FROM AUTHOR]

This work is focused on the development of o/w salad dressing-type emulsions stabilized by tuna proteins. The influence of protein conservation methods after the extraction process (freezing or liofilization) on the rheological properties and microstructure of these emulsions was analyzed. Processing variables during emulsification were also evaluated. Stable emulsions with adequate rheological and microstructural characteristics were prepared using 70% oil and 0.50% tuna proteins. From the experimental results obtained, we may conclude that emulsion rheological properties are not significantly affected by the protein conservation method selected. On the contrary, an increase in homogenization speed favours an increase in the values of the linear viscoelastic functions. Less significant is the fact that as agitation speed increases further, mean droplet size steadily decreases. [ABSTRACT FROM AUTHOR]

This work is focused on the development of o/w salad dressing-type emulsions stabilized by tuna proteins. The influence of protein conservation methods after the extraction process (freezing or liofilization) on the rheological properties and microstructure of these emulsions was analyzed. Processing variables during emulsification were also evaluated. Stable emulsions with adequate rheological and microstructural characteristics were prepared using 70% oil and 0.50% tuna proteins. From the experimental results obtained, we may conclude that emulsion rheological properties are not significantly affected by the protein conservation method selected. On the contrary, an increase in homogenization speed favours an increase in the values of the linear viscoelastic functions. Less significant is the fact that as agitation speed increases further, mean droplet size steadily decreases. [ABSTRACT FROM AUTHOR]