Microstructure Friction Thickeners Seaweed Rheological Behavior Saliva

External authors:

• Leyla Covacevich ( Pontificia Universidad Catolica de Chile )
• Natalia Brossard ( Pontificia Universidad Catolica de Chile )
• Fernando Osorio ( Universidad de Santiago de Chile )

Abstract:

Thickened liquid foods are particularly interesting in culinary applications and the management of swallowing disorders. Polysaccharide molecules and suspended soft particles play a major role in increasing viscosity and mouthfeel. In this work, tribo-rheological effects of finely ground particles (less than 75 mu m) of Durvillaea antarctica seaweed (SP) as a minimally processed and natural alternative to commercial thickeners were studied. Shear viscosity (eta), viscoelastic moduli (G ', G ''), and the coefficient of friction (CoF) were determined for SP dispersions, using as controls two commercial thickeners: modified maize starch-based (TE) and xanthan gum-based (TU). SP and SP dispersions were characterized microstructurally and evaluated at concentrations of 1.2%, 2.4%, and 4.8% w/v, with and without artificial saliva (AS). SP dispersions exhibited a pseudoplastic behavior in the range of shear rates 0.1-100 s(-1) and viscoelasticity (G'>G") in the 0.1-80 rad/s frequency range. The incorporation of AS had a dilution effect in SP and TU dispersions, but additionally, in the case of TE, a hydrolyzing effect decreased the values of the responses. In the tribology experiments, all samples followed a Stribeck curve. SP dispersions were more lubricating than AS and controls in the physiological range of velocities during oral processing and swallowing (e.g.,>100 mm/s). The thickening, viscoelastic, and lubrication behavior of SP dispersions were attributed to the soluble solids released from the SP (37%-51% d. w.) and interactions with ghosts of SP particles in the continuous aqueous phase. Fine seaweed particles may be a sustainable and low-cost alternative to commercial thickeners in some food applications.