VIRUS INACTIVATION IN CONTAMINATED FRUIT PUREE AND JUICE VIA HYDROSTATIC PRESSURE PROCESS

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 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 201