Denaturation manner of sarcoplasmic proteins in Pale, Soft and Exudative meat determines their positive impacts on myofibrillar water-holding capacity

Abstract

The aim of the study was to investigate the denaturation manner of sarcoplasmic proteins (SP) under PSE condition to explain their positive impacts on water-holding compacity. We found that the SP precipitation under PSE-like condition (pH 5.5, 40 °C) and heating conditions (pH 5.5, 7.0, 8.0, 55 °C) were similar, but the myofibrillar water-holding capacity was improved only under PSE-like condition (pH 5.5, 40 °C). To understand the denaturation mechanism of SP, their physicochemical properties were examined. Results demonstrated that PSE-denaturation and heat-denaturation of SP were two different processes. At pH 7.0 and 8.0, the unfolding of SP due to temperature elevation did not alter the overall net surface negative charges but only increased hydrophobicity, whereas at pH 5.5, the net surface positive charges and hydrophobicity increased dramatically. We hypothesized that in PSE meat, denatured SP became highly positively charged and hydrophobic and easier to bind to the negatively charged MF, which is related to the improvement on water-holding capacity.

Keywords: Glycogen phosphorylase; PSE; Precipitation; Surface hydrophobicity; Zeta potential; myofibrils.