High hydrostatic pressure inactivation of murine norovirus and human noroviruses on green onions and in salsa

- Presence of water drastically enhanced HHP inactivation of MNV-1 on green onions.
- Lowering initial sample temperature significantly enhanced HHP inactivation of MNV-1.
- HHP inactivation curves showed a linear relationship between log reduction of MNV-1 and time.
- HHP could inactivate > 3.0 log of HuNoV GII.4 on green onions (in the presence of water) and in salsa.

In this study, high hydrostatic pressure (HHP) was evaluated as an intervention for human noroviruses (HuNoVs) in green onions and salsa. To determine the effect of water during HHP treatment on virus inactivation, a HuNoV surrogate, murine norovirus 1 (MNV-1), was inoculated onto green onions and then HHP-treated at 350 MPa with or without water at 4 or 20 °C. The presence of water enhanced HHP inactivation of MNV-1 on green onions at 4 °C but not at 20 °C. To test the temperature effect on HHP inactivation of MNV-1, inoculated green onions were HHP-treated at 300 MPa at 1, 4 and 10 °C. As the temperature decreased, MNV-1 became more sensitive to HHP treatment. HHP inactivation curves of MNV-1 on green onions and salsa were obtained at 300 or 350 MPa for 0.5-3 min at 1 °C. All three inactivation curves showed a linear relationship between log reduction of MNV-1 and time. D values of HHP inactivation of MNV-1 on green onions were 1.10 and 0.61 min at 300 and 350 MPa, respectively. The D value of HHP inactivation of MNV-1 in salsa at 300 MPa was 0.63 min. HHP inactivation of HuNoV GI.1 and GII.4 on green onions and salsa was also conducted. To achieve > 3 log reduction of HuNoV GI.1, HHP treatments for 2 min at 1 °C should be conducted at 600 MPa and 500 MPa for green onions and salsa, respectively. To achieve > 3 log reduction of HuNoV GII.4, HHP treatments for 2 min at 1 °C should be conducted at 500 MPa and 300 MPa for green onions and salsa, respectively.