Properties of dextran as a cryoprotectant in ice cream

In order to determine the usefulness of dextran as a stabilizer in frozen dairy products, ice cream mixes with varying concentrations of this microbial polysaccharide were prepared and tested by sensory, physical and mechanical means. Although previous results had shown that aqueous solutions of dextran exhibited remarkably low viscosities, the addition of dextrans to ice cream mixes resulted in much higher values. This is thought to result from interactions among dextrans, dairy proteins and, perhaps, other stabilizers. Dextran addition effectively increased the Tg of ice cream mixes, indicative of its value as a cryoprotectant. Also, dextran significantly reduced the sensory perception of ‘iciness intensity’ in heat-shocked ice cream samples. This resulted from the ability of dextran to slow ice crystal growth during storage and thermal abuse, as indicated by reduced ice crystal size as compared to a control formulation. However, dextran also produced unwanted firmness and melting characteristics in ice cream that could influence commercial acceptability.