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Ultralow temperature high pressure processing enhances inactivation of norovirus surrogates
Christina A M DeWitt1, Kevin A Nelson1, Hyung Joo Kim1
1Coastal Oregon Marine Experiment Station, Seafood Research and Education Center, Oregon State University, Astoria, OR, USA.
Abstract:
High pressure processing (HPP) is a powerful non-thermal method for inactivating pathogens. Human norovirus and genetically-related caliciviruses are moderately sensitive to temperatures above 0 °C with >400 MPa (MPa) or higher required to inactivate multiple logs of virus. Sensitivity of murine norovirus (MNV) and Tulane virus (TV) to ice phase transitions was evaluated using ultra low temperature HPP. Identical samples containing MNV or TV were either equilibrated to +1.5 °C (thawed) or -40 °C (frozen) 24 h prior to pressurization. All samples (thawed and frozen) were then placed in a pre-chilled chamber which was then rapidly filled with -40 °C chamber fluid. Samples were immediately pressurized for 5 min at 200, 250 or 300 MPa. Controls were not pressurized. For samples that were thawed and then pressurized in 40 °C chamber fluid, the MNV average log reduction at 200 MPa was 4.4, while >6.1 log reduction (non-detectable) was achieved at 250 and 300 MPa. TV samples averaged 2.3, 5 and 4.3 log reduction at 200, 250, and 300 MPa respectively. For samples that were frozen and then pressurized in 40 °C chamber fluid, the MNV average log reductions were 2.3, 3.2 and 4.2 at 200 MPa, 250 MPa and 300 MPa, respectively, while TV samples averaged 0.81, 2.3 and 1.7 log reductions at 200, 250, and 300 MPa, respectively. Inactivation of TV within oysters at these pressures was also demonstrated. Overall, results indicate that in addition to enhancing inactivation of norovirus surrogates compared to higher temperatures, ultra-cold HPP performed on thawed samples especially enhances inactivation.
Insights
Ultra-low temperature high pressure processing (HPP) significantly enhances inactivation of norovirus surrogates like MNV and TV, especially when applied to thawed samples. This non-thermal method offers improved pathogen control in food safety applications.
Area of Science:
- Food Science
- Microbiology
- Food Safety
Background:
- High Pressure Processing (HPP) is a non-thermal method for pathogen inactivation.
- Human norovirus requires >400 MPa for significant inactivation at temperatures above 0°C.
- Murine norovirus (MNV) and Tulane virus (TV) are used as surrogates to study norovirus inactivation.
Purpose of the Study:
- To evaluate the sensitivity of MNV and TV to ultra-low temperature HPP.
- To compare the inactivation efficacy of HPP on thawed versus frozen samples.
- To assess the potential of ultra-cold HPP for pathogen control in food matrices like oysters.
Main Methods:
- MNV and TV samples were equilibrated to +1.5°C (thawed) or -40°C (frozen).
- Samples were pressurized for 5 minutes at 200, 250, or 300 MPa using ultra-low temperature HPP (-40°C chamber fluid).
- Viral log reduction was determined for both thawed and frozen samples, and TV inactivation in oysters was assessed.
Main Results:
- For thawed samples, MNV achieved >4.4 log reduction at 200 MPa and >6.1 log reduction at 250-300 MPa. TV achieved 2.3-5 log reduction across tested pressures.
- For frozen samples, MNV achieved 2.3-4.2 log reduction and TV achieved 0.81-2.3 log reduction across tested pressures.
- TV inactivation was demonstrated within oysters at the tested ultra-cold HPP pressures.
Conclusions:
- Ultra-cold HPP enhances the inactivation of norovirus surrogates compared to higher temperatures.
- HPP applied to thawed samples demonstrates superior inactivation efficacy for MNV and TV.
- Ultra-low temperature HPP shows promise as an effective food safety intervention, particularly for inactivating viruses in products like oysters.
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