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HIGH PRESSURE PROCESSING CONDITIONS FOR INACTIVATION OF HUMAN NOROVIRUS SURROGATE IN OYSTERS
Title
HIGH PRESSURE PROCESSING CONDITIONS FOR INACTIVATION OF HUMAN NOROVIRUS SURROGATE IN OYSTERS
Creator
Agarwal, Sagar
Date
2015, 2015-07
Description
Noroviruses are the leading cause of acute nonbacterial gastroenteritis in humans. Bivalve mollusks bio-accumulate norovirus as they feed....
Show moreNoroviruses are the leading cause of acute nonbacterial gastroenteritis in humans. Bivalve mollusks bio-accumulate norovirus as they feed. High pressure processing (HPP), a non-thermal processing technology, can inactivate microorganisms in foods while preserving flavor, appearance, nutritional value, and extending shelf-life. In the present study, we have systematically investigated the effect of parameters such as temperature, salinity and product composition on the efficacy of HPP for inactivation of human norovirus surrogate. For temperature analysis MNV-1 suspended in aqueous media, oyster homogenate, and bio-accumulated in whole oysters were treated with pressures varying from 200-500 MPa at 4, 10, and 20oC with a hold time of 1 minute. In media, a 4-log10 reduction was observed upon treatment at 300 MPa for 1 minute at 4oC, whereas pressures of 400 and 500 MPa were required for a comparable reduction at initial processing temperatures of 10 and 20oC. Colder temperature promoted higher reduction in virus titer at a given pressure. Addition of 1, 2 and 3% (w/v) sea salt to aqueous media provided significant baroprotective effect at colder temperatures. While pressure of 300 MPa for 1 min at 4oC was sufficient to achieve 3-log10 reduction for MNV-1 suspended in 1% (w/v) sea salt media, the same conditions resulted in only 1.4-log10 reduction for MNV-1 suspended in 3% (w/v) sea salt media. However increasing processing temperature the minimized the baroprotective effects. Similar results were observed for the effect of food matrix on virus survival, with significant baroprotective effect at colder temperatures and a minimal impact of matrix on increasing processing temperature. For initial processing temperature of 4oC a 300 MPa treatment with a hold time of 1 min resulted in a 4-log10 reduction for MNV-1 suspended in aqueous media, 3.35-log10 reduction in oyster homogenate, and <1-log10 reduction in whole oysters. Whereas at higher initial processing temperatures of 10 and 20oC the difference in reduction between matrices was insignificant. A comparison of temperature v/s salinity and temperature v/s composition revealed that effects of temperature far outweighed the impact of product properties (salinity and composition).Whole oysters seeded with MNV-1 treated at 350 MPa for 1 min at 4oC was found to have a 4-log10 reduction, while MNV-1 suspended in aqueous media at 20oC on similar treatment had a 0.5-log10 reduction. Similarly MNV-1 suspended in aqueous media with 3% salt when treated with 400 MPa for 1 min at 4oC resulted in a 5-log10 reduction, whereas MNV-1 suspended in aqueous media at 20oC on similar treatment had a 1.9-log10 reduction. Oyster processors should use refrigerated temperature to achieve higher reduction in virus titer at lower pressures.
M.S. in Food Safety and Technology, July 2015
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