Microfluidization of full-fat ice cream mixes: Effects on rheology and microstructure

Full-fat ice cream mixes with xanthan or locust bean gum (LBG) were subject to microfluidization at 220-250 MPa, then formed into ice cream. Particle size increased with average values increasing from 2.64 to 3.93 mu m for xanthan mixes, and 2.51 to 4.72 mu m for LBG mixes, suggesting interaction between polysaccharide and protein components that then aggregate at the lipid interface. Microfluidization marginally increased the shear-thinning behavior of mixes while dramatically increasing consistency, with xanthan mixes increasing from K = 1.34 to 13.21 Pa s(n), and LBG mixes from 0.127 to 10.64 Pa s(n). Oscillatory tests showed the ice cream from microfluidized mixes were softer, with G ' decreasing four-fold for microfluidized xanthan-based ice cream. All samples showed G ' and G '' increased with frequency for samples at -10 degrees C, with G '' generally greater than G ', and suggesting a transition-to-flow region over the frequency range of 0.1-100 Hz. Transmission electron microscopy showed that hair-like structures present on casein were lost after microfludization, potentially enhancing aggregation of protein. Scanning electron microscopy also showed distinct differences between ice cream made from control and microfluidized mixes. Overall, the changes observed were more pronounced in the LBG formulation, which we believe is due to the differences in structure between the two gums. Practical Applications Hydrocolloid stabilizers are a common ingredient of ice cream. This work shows that high-pressure homogenization can be used to alter the nature of protein-polysaccharide interactions in ice cream mix, ultimately increasing mix viscosity and component interactions. Previous work has shown this can improve ice cream creaminess and sensory properties. Alternately, this work suggests that desirable ice cream properties could be attained with lower levels of stabilizers by using microfluidization.