Freezing kinetics and microstructure of ice cream from high-pressure-jet processing of ice cream mix

The effect of high-pressure-jet (HPJ) processing (0-500 MPa) on low-fat (6% fat) ice cream was studied by evaluating physiochemical properties before freezing, during dynamic freezing, and after hardening. An HPJ treatment >= 400 MPa decreased the density, increased the apparent size of colloidal particles, and altered rheological behavior (increased non-Newtonian behavior and consistency coefficients) of low-fat ice cream mix before freezing. During dynamic freezing, the particle size and consistency coefficient decreased but remained higher in 400 MPa-treated samples vs. non-HPJ-treated controls at the conclusion of freezing. The resulting ice creams (400 and 500 MPa-treated) had similar hardness values (3,372 +/- 25 and 3,825 +/- 14 g) and increased melting rates (2.91 +/- 0.13 and 2.61 +/- 0.31 g/min) compared with a control sample containing polysorbate 80 (3,887 +/- 2 and 1.62 +/- 0.25 g/min). Visualization of ice cream samples using transmission electron microscopy provided evidence of casein micelle and fat droplet disruption by HPJ treatment >= 400 MPa. In the 400 MPa-treated samples, a unique microstructure consisting of dispersed protein congregated around coalesced fat globules likely contributed to the altered physiochemical properties of this ice cream. High-pressure-jet processing can alter the microstructure, rheological properties, and hardness of a low-fat ice cream, and further modification of the formulation and processing parameters may allow the development of products with enhanced properties.

Automated summary

High-pressure-jet processing can alter the physiochemical properties of low-fat ice cream by changing the density, particle size, rheological behavior, hardness, and melting rate. This treatment disrupts casein micelles and fat droplets, leading to unique microstructures and potentially enhanced properties of the ice cream.