Effect of high-pressure homogenization on droplet size distribution and rheological properties of ice cream mixes

Representative volume-weighted distributions of ice cream mix samples: A) unhomogenized (CON); B) homogenized at 15 and 3 MPa pressure (CP); C) homogenized at 97 and 3 MPa pressure (HP).

Mean fat globule volume-weighted diameters of ice cream mixes with 5% and 8% fat content and aged for 4 h (panel 1) or 20 h (panel 2). CON = unhomogenized; CP = homogenized at 15 and 3 MPa pressure; HP = homogenized at 97 and 3 MPa pressure. Statistical analysis (Tukey's HSD test, P<0.05) was carried out within groups at different fat content; lowercase letters refer to 5% fat content mixes, and uppercase letters refer to 8% fat content mixes. Asterisks mark statistically different pairs (Student's t-test, P<0.05).

Optical light microscope images of mixes at 5% (left column) and 8% (right column) fat content. CON = unhomogenized; CP = homogenized at 15 and 3 MPa pressure; HP = homogenized at 97 and 3 MPa pressure. Magnification 1,000×; scale bar = 25μm.

Representative steady shear flow curves of 5% fat and 8% fat ice cream mixes aged for 4 and 20h. CON = unhomogenized; CP = homogenized at 15 and 3MPa pressure; HP = homogenized at 97 and 3MPa pressure.

Logarithmic plot of shear stress versus shear rate of ice cream mixes. CON = unhomogenized; CP = homogenized at 15 and 3MPa pressure; HP = homogenized at 97 and 3MPa pressure. Inner rectangle: Theoretical shear thinning (a) and plastic (b) behaviors reported in Lapasin and Pricl (1995).

Representative mechanical spectrum of an HP (high-pressure) mix (homogenized at 97 and 3MPa).

Mean values and standard deviations of complex modulus of ice cream mixes at 5% and 8% fat content aged for 4 and 20h. CON = unhomogenized; CP = homogenized at 15 and 3MPa pressure; HP = homogenized at 97 and 3MPa pressure.

Cox-Merz superposition of steady shear flow viscosity (η) versus shear rate (γ, ■) and complex viscosity (η*) versus frequency (ω, □) for samples at 5% fat (left column) and 8% fat (right column) aged for 20h.