Effect of temperature on viscoelastic properties of semisolid dairy desserts

The “natillas”, semisolid dairy dessert of wide consumption in Spain, is composed of milk, starch, hydrocolloids, sugars, colorants and aromas. The particular characteristics of some ingredients, like fat content of milk, type of starch, and/or type and concentration of hydrocolloids, and their crossed interactions, will be reflected in notable differences in their rheological and sensory properties. Little information is available on the differences to be found in commercial samples of this type of dairy desserts [1]. The rheological properties of this type of products, are due to a biphasic structure defined by the characteristics of the dispersed phase (starch granules) and by the viscosity of the dispersing phase [2]. The effects of starch content on the viscoelasticity of similar products (Dutch “vla” model systems) have been recently reported [3]. The objectives of this work are to characterise the viscoelastic properties of commercial samples of Spanish “natillas” and to study the effect of the consumption temperatures (5 and 25ºC) on them.