Ice cream is a complex colloidal food matrix composed of different structural elements, i.e., air cells, ice crystals and partially coalesced fat droplets dispersed in a continuous freeze-concentrated aqueous phase. Owing to the ice cream structural complexity, small amplitude oscillatory shear (SAOS) rheology has been successfully applied for the viscoelastic characterisation of ice cream as influenced by the mix composition, freezing process and frozen storage conditions. Large amplitude oscillatory shear (LAOS) rheology is an emerging characterisation method in the domain of food colloids due to its ability to allow “near real measurement” of complex food systems. Hitherto, LAOS has been successfully employed for the assessment of the techno-functional interplay of food ingredients (e.g. proteins, polysaccharides, fats, etc) and understanding the structural complexity of real food matrices such as emulsions, foams and gels. Nonetheless, the interrelationship between LAOS properties and sensory textural aspects involving large deformation without solid-to-molten physical state transitions has not yet been explored. The aim of the present work was to showcase the feasibility of LAOS as an instrumental tool for associating the changes in the structural integrity of ice cream with its major tactile sensory modalities at serving temperature.

Three common tactile sensory properties of ice cream i.e., resistance to scooping (scoopability), creaminess and gumminess were assessed in high protein formulations differing in their protein to fat ratio (φ _P/F = 0.9 to 4) and protein source (milk protein concentrate (MPC) vs whey protein isolate-sodium caseinate (WPICAS) 1:1 blend). The complex viscosity – angular frequency data obeyed the TCS principle with the calculated shift factors reflecting effectively the compositional profile of ice creams i.e., a _c ∝ φ_P/F ^1.16 and φ_P/F^2.23, b _c ∝ φ_P/F ^−1.27 and φ_P/F ^−1.75 for MPC and WPICAS fortified systems. LAOS assessment revealed a clear impact of protein type and φ _P/F on the shearing deformation of ice creams. MPC fortification and decrease in the φ _P/F enhanced the shear flowing ability of the ice creams. In all cases, the onset of shear stiffening and thickening behaviour was observed at shear stresses below the flow point, which indicates gel-like or colloid glass-like structures. According to partial least squares regression analysis, the TCS parameters (a _c and b_c), damping factor (tanδ) and the shear strain (γ_f) and elastic modulus (log G’_f) at flow point were determined as the most important parameters predicting tactile sensory modalities on large deformation (spooning) such as scoopability, creaminess and gumminess.

Conference Theme: Physical properties of food hydrocolloids for enhanced product development