Rheological properties of aqueous dispersions of chia (Salvia hispanica L.) mucilage

Abstract

The viscoelastic and flow behavior of aqueous dispersions with different concentrations of chia mucilage (Salvia hispanica L.) from Argentina seeds was characterized. The mucilage was obtained by two methods: (I) soaking-freezing-freeze drying-sieving, and (II) soaking-filtration-concentration-freezing-freeze drying. The effect of mucilage concentration, temperature, pH, ionic strength and presence of sucrose on the rheological properties of the aqueous dispersions with the addition of NaCl or CaCl2 was also evaluated. All the dispersion samples presented a shear-thinning behavior and a weak elastic gel-like structure because the storage modulus (G′) was larger than the loss modulus (G″) in the studied frequency range. The concentration of mucilage was the variable with the most significant effect on k (consistency index), whereas the presence of sucrose had the highest effect on n (flow behavior index) and tan δ. The type of salt and extraction method significantly affected k, not affecting n. Tan δ was affected mainly by the type of salt, and some interaction was observed between both factors. Method II and NaCl provided a higher consistency to the dispersions of chia mucilage. These results suggest that chia mucilage could be applied in the production of foods that require additives with thickening capacity, taking advantage of the zero calorific value of this hydrocolloid.