Application of high hydrostatic pressure for the inactivation of norovirus and quality stability in fresh sea squirt (Halocynthia roretzi)

Abstract

Sea squirt (Halocynthia roretzi) is considered a potential cause of human norovirus in Korea. This study investigated the effect of high hydrostatic pressure at 100-500 MPa for 5 min at room temperature (23 +/- 2 celcius) on the inactivation of murine norovirus-1 (initial inoculum of 6-7 log(10) plaque forming units/ml) as a human norovirus surrogate in fresh sea squirt. The effects of high hydrostatic pressure on the Hunter colors and pH were also examined as the main indices of quality. No reductions in murine norovirus-1 titers were observed in sea squirt treated at 100-400 MPa. However, murine norovirus-1 in sea squirt was completely inactivated by 500 MPa of high hydrostatic pressure. Furthermore, the Hunter colors ("L," "a," and "b") and pH values (6.10-6.19) were not significantly (P > 0.05) different between non-high hydrostatic pressure-treated sea squirts and all high hydrostatic pressure-treated sea squirts. Therefore, 500 MPa of high hydrostatic pressure at room temperature may be an optimal treatment for Tunicata meat without altering the food quality (color and pH).