Rheological properties of kefiran compared to other neutral gums

PIERMARIA, JUDITH; BENGOECHEA, CARLOS; ABRAHAM ANALÍA G.; GUERRERO, ANTONIO

Coimbra

Congreso; IBEREO 2015 Challenges in rheology and product development; 2015

Ibero-American Societies of Rheology

Kefiran is a water-soluble branched glucogalactan containing equal amounts of D-glucose and D-galactose produced by microorganisms present in kefir grains. Aqueous dispersions of kefiran (K) were compared to three selected neutral gums used as reference: methylcellulose (MC), locust bean gum (LBG) and guar gum (GG). Their rheological behaviour is characteristic of low concentrated polysaccharide dispersions, in which a fluid-like behaviour is predominant at most frequencies studied. The neutral gums 2% solutions may be ranked, matching their molecular weights, according to their viscoelastic behaviour: GG > LBG > MC > K. Moreover, an increase in the gum concentration from 0.5 to 2% wt generally yields a strengthening of the structure.Cross model is properly used to describe the shear-thinning behaviour of all the neutral gum solutions studied. Moreover, if log 0 is represented versus log (polymer concentration) for the four gums, a linear fitting may be properly applied. Kefiran solutions do not show important extensional properties at 2%, displaying a behaviour close the Newtonian at low Hencky strains.Thus, regarding the potential of kefiran as functional additive in food products, it may be necessary to consider the future addition of another ingredient into the formulation if higher viscoelastic properties are needed.