The reason for the decreases of the soluble protein content and degree of hydrolysis under 400–500 MPa of pressure was probably caused by partial protein denaturation and condensation. In the process of UHP, pressure can induce protein aggregation because buried hydrophobic and –SH groups become surface-exposed, which leads to protein unfolding gradually due to hydrophobic interactions (Tedford,Smith, & Schaschke, 1999; Yin et al., 2008). When the pressure decreased, the surface exposure of these hydrophobic bonding and –SH groups will be connected with –SH binding in new hydrophobic interactions, which leads to the aggregation of dena- tured proteins (Yin et al., 2008).