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This study aims to extend the range of applications of tragacanth gum by studying its incorporation into bioplastics formulation, exploring the influence that different gum contents (0-20wt.%) exert over the thermomechanical and water uptake properties of bioplastics based on egg white albumen protein (EW). The effect of plasticizer nature was also evaluated through the modification of the water/glycerol ratio within the plasticizer fraction (fixed at 40wt.%). The addition of tragacanth gum generally yielded an enhancement of the water uptake capacity, being doubled at the highest content. Conversely, presence of tragacanth gum resulted in a considerable decrease in the bioplastic mechanical properties: both tensile strength and maximum elongation were reduced up to 75% approximately when compared to the gum-free system. Ageing of selected samples was also studied, revealing an important effect of storage time when tragacanth gum is present, possibly due to its hydrophilic character.

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Inulin is a prebiotic ingredient that is being increasingly used in food formulations as fat replacer. The present manuscript focuses on the formation of gels formed from inulin aqueous dispersions, observing the effect of inulin content, ranging from 25 to 50 wt%, and of the presence of calcium salts (chloride, lactate) at different concentrations up to 5 wt% Gels are observed to be stronger and formed in a shorter time as the polysaccharide content is higher. Both backscattering and rheological techniques can be used to follow the gelation, being able to detect a significant initial setting stage at 25 wt% inulin content. When calcium salts are added, weakening of gels takes place, resulting in lower values of the storage and loss moduli, G' and G'', respectively, as well as in a reduction of the linear viscoelastic range. Moreover, gelation seems to be retarded on a large scale of time due to the presence of salt. Prebiotic gels containing calcium are of special interest for the development of functional foods, always considering the effect they exert on the rheology when formulating these products.