Control samples and samples with xanthan (0.09% w/w at the final solution) were prepared and heated at temperatures from 60 to 90 8C for 5
or 30 min. Additionally, the viscosity of starch–xanthan mixtures was calculated at different shear rates. Regarding these mixtures two
preparation techniques were used: separate preparation of starch and xanthan solutions and subsequent mixing (a), or mixture of the powders
prior to addition of water (b). Samples were heated at two different temperatures 75, 90 8C and times 5, 30 min. According to SP values and
granules dimensions at 75 8C, xanthan addition enhanced swelling. It also enhanced starch polymers leakage at temperatures ,80 8C. At
higher temperatures lower SOL values were found than those of control samples. Furthermore, in the presence of xanthan the proportion of
large granules was greater than this found in aqueous solution. However, xanthan induced granules folding, which was noticed even at
relatively low temperatures (75 8C). With respect to viscosity, all samples showed pseudoplastic behaviour. Experimental values were fitted
well by the Ostwald–de Waele model ðs ¼ k·g_
nÞ: Consistency values ðkÞ and flow index ðnÞ were mainly influenced by the preparation
technique and the heating temperature. Mixtures prepared with technique (a) had increased viscosity, consistency and pseudoplasticity.
Mixtures prepared with technique (b) had irregular granules’ shape and size due to xanthan addition and bad adhesion between continuous
and dispersed phase, which influence viscosity negatively.