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- Title
- PULSED LIGHT INACTIVATION OF MURINE NOROVIRUS ON VARIOUS FOOD CONTACT SURFACES
- Creator
- Zhou, Zijin
- Date
- 2015, 2015-07
- Description
-
Norovirus is one of the leading causes for foodborne illness. Transmission of virus from surface to food has been known to cause a number of...
Show moreNorovirus is one of the leading causes for foodborne illness. Transmission of virus from surface to food has been known to cause a number of outbreaks. Studies of norovirus have been conducted using Murine Norovirus to simulate the behaviors. Pulsed light (PL) is a promising surface decontamination technology, which has the potential to be applied in a food service setting. PL uses intense pulses of short duration and a broad spectrum to accomplish microbial inactivation. This study evaluates the effect of PL on MNV-1, artificially inoculated onto various food contact surfaces including 304 stainless steel, glazed tile, polypropylene, and ultra-high molecular weight (UHMW) polyethylene. The virus was allowed to inoculate on the coupons for 20mins and treated with PL in a Xenon Steripulse XL-3000TM pulsed light treatment system for up to 60 s, at a distance of 8.3 cm 10.8 cm or 13.3cm from the central axis of the lamp. An infrared (IR) camera was used to record surface temperatures, in 1-s increments. After PL treatments, remaining viruses were recovered from surfaces and quantified by plaque assay. At a distance of 10.8cm, MNV-1 was reduced by 2.22-, 2.27- 2.75- and 3.12-log, after 20s treatment on inoculated stainless steel, glazed tile, UHMW polyethylene and polypropylene, respectively. After 50s treatment, MNV-1 was reduced by 4.86- and 5.93- log on glazed tile and stainless steel surface respectively. The surface temperature on tile and stainless steel increased at the rate of 1.08±0.20 and 1.28±0.32°C /s respectively. A relatively short treatment using pulsed light is sufficient to inactivate MNV-1 on the surface of materials commonly used in food preparation. The results suggest that the technology has the potential to reduce surface viral contamination in a food preparation setting.
M.S. in Food Safety and Technology, July 2015
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- Title
- VIRUS INACTIVATION IN CONTAMINATED FRUIT PUREE AND JUICE VIA HYDROSTATIC PRESSURE PROCESS
- Creator
- Pan, Hao
- Date
- 2015, 2015-07
- Description
-
The use of the high hydrostatic pressure process (HPP) of food allows for retention of many sensory qualities. However, it is not clear if the...
Show moreThe use of the high hydrostatic pressure process (HPP) of food allows for retention of many sensory qualities. However, it is not clear if the process is effective in inactivating viruses on contaminated produce. This study’s objective is to evaluate the factors that affect the survival of viral surrogates MS2 coliphage and murine norovirus MNV during HPP treatment of fresh fruit puree and juice. Fresh strawberries and frozen pomegranate arils were used to prepare separate puree or juice products which were inoculated with the viral surrogates for each trial. The inoculated juice or puree was prepared for treatment treated in an Avure QFP 24L-828-S HPP pilot system using process temperatures of 10 to 40⁰C, pressures ranging from 250 to 600 MPa, and holding times from 1.5 to 3 mins. After HPP treatments, MNV/MS2 inoculated sample matrices were eluted and quantified. Control samples were prepared in the same way, but did not receive HPP treatment. The recovery range in the control samples was 12 to 40% for MS2 or MNV from inoculated puree and juice. In treated samples, it was found that viruses (MNV or MS2) survived better in the semi-solid puree as compared to liquid matrices (juice or medium) regardless of pH. In general, higher pressures enhanced the virus inactivation with constant holding time and temperature. However, MS2 was found more resistant to HPP treatment than MNV, though the trend of their responses to HPP are consistent. The MS2 inactivation in strawberry puree was more efficient under the treatment with higher HPP temperature. Surprisingly, an opposite trend was observed for MNV inactivation. Among 11 HPP trials, the MNV inactivation in strawberry juice has no significant difference from that in pomegranate juice. Overall the results of this study provide valuable information on the effect of food matrix, holding temperature and pressure on virus survival during hydrostatic pressure process of fruit puree and juice. MS2 coliphage is somewhat resistant to HPP in fruit puree and juice, suggesting it could serve as an indicator for human enteric virus particularly hepatitis A virus in future studies.
M.S. in Food Safety and Technology, July 2015
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- 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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