Purpose: The objective of this study was to evaluate the sensory effects and to compare the inactivation of viral and bacterial pathogens and their surrogates on fresh and frozen berries using UV-C light and to critically assess the potential of this technology for the berry supply chain.
Methods: Fresh and frozen strawberries, raspberries, and blueberries were spot-inoculated with Hepatitis A virus (HAV), Murine Norovirus (MNV), Listeria spp., Salmonella spp., STEC, and their surrogates (MS2 bacteriophage, Listeria innocua, Enterococcus faecium, and Escherichia coli) and treated with UV-C using a 95 W high output UV-C emitter. Samples were exposed to UV-C for up to two minutes. After treatments, viruses and bacteria were recovered and quantified using infectivity assays and selective media, respectively.
Results: A sensory evaluation demonstrated the same sensory properties in treated versus non UV-C treated berries. Results were analysed by determination of tolerance intervals, instead of standard deviation. One log reduction of HAV and MS2 was ensured in 95% of cases, for fresh and frozen strawberries, raspberries, and blueberries with a treatment of 120 sec. Against MNV, the exposure of fresh blueberries for 120 sec was the only UV-C treatment that ensured a reduction of more than one log. For all three berry types, inoculated with the three bacterial cocktails, a one log reduction could not be ensured in 95% of cases.
Significance: The present study shows the opportunities and weaknesses of the UV-C technology when applied to complex food matrices, such as berries.