Tailoring the rheological properties of pea and whey protein hybrid emulgels using high-pressure homogenization treatment on pea protein suspensions

This study investigated the impact of high pressure homogenization (HPH) on the nonlinear rheological behaviour of pea, whey and pea:whey hybrid emulgels. Pea protein suspensions (5.5% protein) were pre-treated with HPH (6-600 MPa), prior to mixing with untreated whey proteins to form hybrid suspensions. Whey protein suspensions showed the smallest particle size (0.5 μm) and high solubility (94%). In pea protein suspensions, HPH progressively reduced particle size and increased solubility, reaching 7.9 μm and 94.4% at 100 MPa, respectively, whereas it promoted the formation of larger aggregates in hybrid suspensions, leading to larger particle size (80.1 μm at 100 MPa) and a consistent solubility (57.6 ± 1.6%). Rheological measurements demonstrated that whey proteins formed the strongest emulgels, while pea emulgels exhibited the highest storage modulus (G′), at 15 MPa. In contrast, hybrid emulgels exhibited greater gel strength at 100 MPa, with G′ (1 Hz) increasing from 5.5 kPa in the untreated sample to 14 kPa. Lissajous-Bowditch figures revealed that hybrid emulgels showed more gradual transitions from solid-to liquid-like behaviour with increasing strain amplitude, compared to untreated samples. The quantification of nonlinear responses using the Chebyshev decomposition method confirmed strain stiffening and shear thinning across all emulgels. Notably, hybrid emulgels showed accelerated increases in stiffening and thickening indices, indicating stronger gels at 100 MPa. This study demonstrated that HPH enables the formulation of hybrid emulgels with improved rheological functionality, providing new fundamental contributions in the understanding, development, and application of such a useful technology to hybrid protein systems.