Influence of xanthan gum on rheological properties and freeze-thaw stability of tapioca starch

Physical properties and storage stability of tapioca starch (TS) can be modified using hydrocolloids. Xanthan gum (Xan) was investigated in this study for further application in TS-based products. The TS and TS/Xan mixtures at a total polysaccharide concentration of 5% w/w (db) were prepared. From RVA pasting profiles, pasting temperature, peak and final viscosities of TS pastes increased with increasing Xan concentration (p < 0.05) whereas the setback values indicating the short-term retrogradation were lower (P < 0.05). Flow curves of all TS and TS/Xan pastes from steady shear measurement exhibited shear thinning behavior. Water separation values of TS/Xan pastes were also lower than those of TS pastes alone from repeated freeze-thaw experiment, indicating Xan preventing the reassociation of starch molecules. The correlation between setback and water separation was investigated and proven to be a useful approach for predicting water separation from RVA setback value at any given freeze-thaw cycles. These results have important implications for the formulation of TS-based products with improved rheological properties and freeze-thaw stability. (C) 2008 Elsevier Ltd. All rights reserved.