Multiple outbreaks associated with foodborne viruses have occurred in recent years due to the consumption of contaminated berry products. High-pressure processing (HPP) has been recognized as a nonthermal processing technology for the food industry that is capable of inactivating viral pathogens while still retaining organoleptic quality.

Researchers from the Illinois Institute of Technology, USA, have been evaluated the application of HPP on inactivation of hepatitis A virus (HAV) on strawberries and blueberries. The results were published on the Journal of Food Protection.

Fresh strawberries and blueberries (25 g) were spot-inoculated with HAV at approximately 4 log PFU/sample. Fresh and frozen berries were vacuum-sealed, packaged, and HPP treated at 200, 300, 400, 500, and 600 MPa for 3 min with an initial temperature at 4°C. After treatment, viruses were extracted and recovered from the samples and quantified by viral plaque assay.

The initial inoculum level of fresh and frozen strawberries was 3.6, 3.5, 3.8, and 4.0 log PFU/sample, respectively. HPP treatment was effective in inactivating HAV in berries, and higher viral inactivation was observed as pressure levels increased. At 400 MPa, greater than 2-log reductions were achieved in strawberries. HAV was reduced to below detection level after 500 MPa treatment in both fresh and frozen strawberries. The inactivation was significantly lower in fresh and frozen blueberries, with 1.1- and 1.2-log reductions at 400 MPa, respectively.

Effective inactivation of HAV is achievable with HPP treatment for strawberries and blueberries. These results suggest HPP is a promising technology to improve microbial quality while retaining sensorial characteristics of berries.