A study showing the successful use of viability PMA-RTqPCR method on complex food matrices as clams and its potential application to evaluate whether heat-inactivation processes comply with a specific set performance criterion in terms or risk reduction was performed by a group of researchers from the University of Bacrcelona, one of the SafeConsume’s partners. In addition, the results from this study are considered of value to perfect a HuNoV heat-inactivation model in shellfish samples.

The aim of the study was to evaluate the effect of heat treatment in clams (Tawera gayi) experimentally contaminated with HuNoV using a PMA-viability RTqPCR assay to minimize measurement of non-infectious viruses, and used HAV as a model to estimate infectivity loss. Spiked clams were immersed in water at 90°C to ensure that internal meat temperature was maintained above 90°C for at least 5 min. The treatment resulted in >3.89 ± 0.24 log10 TCID50/g reduction of infectious HAV, confirming inactivation. For HuNoV, RTqPCR assays showed log10 reductions of 2.96 ± 0.79 and 2.56 ± 0.56, for GI and GII, respectively, and the use of PMA resulted in an additional log10 reduction for GII, providing a better correlation with risk reduction. In the absence of a cell culture system which could be used to determine HuNoV infectivity reduction, a performance criteria based on PMA-RTqPCR log reduction could be used to evaluate food product safety. According to data from this study, heat treatments of clams which cause reductions >3.5 log10 for GII as measured by PMA-RTqPCR assay may be regarded as an acceptable inactivation treatment, and could be set as a performance criterion to test the effectiveness of other time-temperature inactivation processes.

The paper describing this study, which is entitled Inactivation of Hepatitis A Virus and Human Norovirus in Clams Subjected to Heat Treatment, is published in Frontiers in Microbiology, a leading journal in its field and the 3rd most cited Microbiology journal in the world (impact factor 4.076).

The authorship belongs to Cristina Fuentes (first author), Francisco J. Pérez-Rodríguez, Aurora Sabrià, Nerea Beguiristain, Rosa M. Pintó, Susana Guix (corresponding author), and Albert Bosch (corresponding author), a group of scientist from the University of Barcelona, Spain.

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