VISCOSITY OF ICE-CREAM MIX AT PASTEURIZATION TEMPERATURES

To calculate the holding times of ice cream mixes in the tubes of HTST pasteurizers, accurate viscosity data are needed for the temperatures and the shear rates of interest. Apparent viscosity was determined fo r ice cream mixes at 80-degrees-C using shear rate sweeps in a CarriMe d rheometer. Mixes varied in fat percentage, milk SNF, sweetener conte nt, type of polysaccharide (guar, locust bean gum, carboxymethyl cellu lose, xanthan), polysaccharide concentration, and blended proprietary stabilizer type and concentration. The effect of dissolution time was also studied. Data were fitted to the power law model, and the best es timate of flow behavior index was .7 for all mixes except those with x anthan gum, in which case the estimate was .5. The consistency coeffic ient is reported for all combinations described and provides useful da ta for equipment design and regulatory needs. The effect of the consis tency coefficient on Reynolds number in holding tubes is also discusse d.