Impact of Different Mechanical Treatments on the Microstructure and Gelling Properties of Peruvian Squid Protein-Polysaccharide Composite Gels.

Peruvian squid myofibrillar protein exhibits poor heat-induced gel strength, which restricts its high-value utilization. To address this limitation, we integrated protein-polysaccharide composite gel formation with physical modification as a potential strategy. This study systematically compared three mechanical treatments-high-pressure homogenization (HPH), colloid milling (CM), and wet comminution (WC)-to elucidate their distinct impacts on the microstructure, rheological properties, and water distribution of the composite gels. HPH (80 MPa) produced uniform sub-micron protein aggregates (400-600 nm) and enhanced molecular flexibility (β-turn: 34.48%), leading to a homogeneous gel network with the highest strain tolerance. In contrast, CM induced rapid, non-specific protein aggregation dominated by rigid β-sheets, resulting in a brittle network with the lowest strength and the most severe water loss (immobile water PT22: 0.80%). WC generated a particle-filled composite structure from large micro-agglomerates (> 5000 nm); consequently, its high hardness (78.63 N) was attributed to the mechanical resistance of these hard filler particles rather than an integrated gel network. In conclusion, among the methods tested, HPH is the most suitable for creating flexible and homogeneous gels. This study provides a mechanistic basis for selecting physical modification technologies to tailor the texture of protein-polysaccharide gels, thereby facilitating the sustainable and high-value utilization of underutilized aquatic resources like Peruvian squid.