Effects of high hydrostatic pressure (HHP) on protein structure and digestibility of red abalone (Haliotis rufescens) muscle

The protein secondary structure modifications and digestibility of red abalone muscle subjected to high hydrostatic pressure (HHP) treatments (200, 300, 400, and 500 MPa for 5 min) were evaluated. The protein structure was analysed by Fourier-Transformed Infrared spectroscopy. Protein digestibility was evaluated based on the degree of hydrolysis (DH) and peptide size distributions under in vitro gastrointestinal conditions. The intermolecular β-sheet structure was disrupted at 200 MPa, compensated by the formation of the intramolecular β-sheet. At 300 and 400 MPa, the β-sheet structure can fold on itself from the interactions that stabilize the protein structure. The 3₁₀-helix structure was significantly looser at 300 MPa. Structural modifications were accompanied by β-turn formation at 300, 400, and 500 MPa. In vitro gastrointestinal digestion is improved by HHP independently of pressure level. The results suggest that high pressure improve the DH of red abalone as a consequence of β-sheet and β-turn conformations changes. Industrial relevance: The seafood industry uses high hydrostatic pressure (HHP) technology to reduce undesirable sensory changes and preserve the functional and nutritional properties of compounds. The HHP experiments contributed to unravel the impact of the different level pressure on digestibility. HHP treatment can change the secondary structures of proteins and improve the protein digestibility as function the pressure level. The results of this study provide valuable information for the potential application of HHP on the development of red abalone with high-nutritional value.