Rheological and sensory properties of dessert sauces thickened by starch-xanthan gum combinations

Strawberry sauces thickened with oat, potato, and corn starches blended with xanthan gum were prepared and their sensory, textural, and rheological properties evaluated. The sensory analysis was performed with the five-point scale of quality. The products were also characterized rheologically at 25 degrees C in the controlled rate of shear (CR) mode. Resulting flow curves were fitted to the Herschel-Bulkley and Ostwald-de Waele rheological models. The second model provided worse fitting. The K and n parameters of the Herschel-Bulkley model revealed that, although to a different extent, all thickener combinations were suitable for thickening of sauces. The textural analysis of the sauces involving so-called back extrusion tests, providing maximum positive and negative extrusion force, revealed that thickening with potato sauce requires less xanthan gum for reaching desired effect, than corn and oat starches did. Sensory analysis distinguished the potato starch containing 0.12% xanthan gum as superior thickener. The sensory properties of the sauces insignificantly changed on the 3-month storage. All sauces were pseudoplastic, shear thinning liquids with the properties varying in time. The structure of the sauces thickened with potato and corn starches was statistically significantly more stable on storage than these thickened with oat starch. (c) 2006 Elsevier Ltd. All rights reserved.