The effect of salep content on the rheological characteristics of a typical ice-cream mix

Salep is a natural stabilizing agent used widely in Turkish-type ice cream. The traditional concentration of salep added to these ice creams is about 0.78%. The effect of salep concentration on the rheological characteristics of a representative ice cream, prepared from whole cows' milk and sugar, was studied together with a water-salep-sugar mix using a Brookfield viscometer. The temperature-dependency of the apparent viscosities of the samples with different salep concentrations was determined. The empirical power law model was observed to fit the apparent viscosity-rotational speed data (r(2): 0.954-0.999). The power-law index values (n) of milk-salep-sugar and water-salep-sugar mixes were in the range of 0.95-0.77 and 0.99-0.85, respectively. This is an indication that milk-salep-sugar mix is non-Newtonian at all concentrations and temperatures studied. A gradual increase in salep concentration was found to alter the rheological characteristics of water-salep-sugar mix from Newtonian to non-Newtonian. Salep concentration was more effective on viscosity change than temperature. (C) 2000 Elsevier Science Ltd. All rights reserved.