Characterization of the impact of freezing on ripened Gouda cheese using small and large amplitude oscillatory shear rheology

In this study, small amplitude oscillatory shear rheology (SAOS) and large amplitude oscillatory shear rheology (LAOS) were applied as complementary techniques to map the impact of two different freezing schemes, i.e., multiple rapid freeze-thaw cycles (FTC; −18 ± 1–6 °C) and quiescent frozen storage (FrS; −18 ± 1 °C, 3-months), on rheological and microstructural properties of aged (9 months) Gouda cheese. The modes of impact of FTC and FrS treatments were different, and LAOS was found to be a powerful tool to quantify such differences at practical deformation scales. The activation energy (Ea) of flow calculated above and below the crossover temperature (53.2 ± 1.6 °C) and frequency-dependence of storage (G′) modulus were used to quantify freezing-induced thermo-rheological changes in the SAOS region. At large incremental deformations (10–360%), freezing impacted the intracycle elastic (G’_L, G’_M) moduli and intracycle viscous (η^’_L, η^’_M) moduli, resulting in strain-dependent zones of strain-stiffening and shear-thinning in the cheese matrix. Micro-cracks observed by confocal laser scanning microscopy (CLSM) were consistent with observed changes in the linear and non-linear rheological responses. This study provides a critical understanding of differences in the effects of FTC and FrS-type treatments, pertinent to practical frozen storage scenarios of Gouda cheese and other semi-hard dairy matrices.