Protein Changes Caused by High Hydrostatic Pressure (HHP): A Study Using Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared (FTIR) Spectroscopy

Abstract

The aim of this study was to evaluate the effect of HHP and rigor state on palm ruff (Seriolella violacea) muscle proteins. HHP treatments were performed at 450-550 MPa for 3 and 4 min at 15°C. Protein secondary structure was evaluated by using Fourier transform infrared spectroscopy, and the thermal behavior was evaluated by using differential scanning calorimetry. The results showed that HHP treatments reduced a-helix and increased b-sheet in fish protein structures. Throughout the 35-d storage period, secondary structures in HHP samples changed depending on pressure intensity, holding time, and rigor state. The thermograms of palm ruff muscles showed four endothermic transitions in prerigor state and three in postrigor state. The HHP treatment affected thermal stability of myosin protein, which is reflected in the change of denaturation temperature (T d ) and a decrease in denaturation enthalpy (DH d ) with respect to the native protein; actin was denatured by the pressure treatments. In conclusion, rigor state and HHP affected protein structure of fish proteins.

High Pressure Processing of Lipase (Thermomyces lanuginosus): Kinetics and Structure Assessment

“…Increased ratio of β‐sheet at increased pressure was consistent with the increase of this component of pressure treated fish protein . This finding suggested increased protein–protein interactions, which enhanced the formation of β‐sheet intramolecular structures.…”

“…[10] Lipase stability at HPP was achieved by changes in its conformation to compensate the loss of hydrophobic and columbic interactions. [5] Increased ratio of -sheet at increased pressure was consistent with the increase of this component of pressure treated fish protein. [5] This finding suggested increased protein-protein interactions, which enhanced the formation of -sheet intramolecular structures.…”

“…Lipase from T. lanuginosus is composed of a central eight‐stranded parallel β‐sheet structure with five interconnecting α‐helix structures . Lipase stability at HPP was achieved by changes in its conformation to compensate the loss of hydrophobic and columbic interactions …”

“…Enzymes can be reversibly or irreversibly enhanced or inactivated by HPP, depending on pressure, temperature, and time conditions applied . Since protein conformation and functionality are sensitive to this technology, the effects of pressure are different for each molecule, leading to pressure transitions such as denaturation, aggregation, or gelation …”

“…[4] Since protein conformation and functionality are sensitive to this technology, the effects of pressure are different for each molecule, leading to pressure transitions such as denaturation, aggregation, or gelation. [5] When a protein is subjected to HPP, water shells into the protein, shifting the equilibrium from the native state to an intermediate or unfolded state. Pressure enhances water infiltration into the protein and causes disassembly of protein cavities, leading to increased hydration and decreased partial molar volume.…”