Grape seed extract for foodborne virus reduction on produce

Grape seed extract (GSE) is reported to have antibacterial properties with few current studies on antiviral activity. Recently, we reported the effects of GSE against foodborne viral surrogates in vitro. This study evaluated the application of GSE (commercial Gravinol-S) against hepatitis A virus (HAV) and human norovirus surrogates, feline calicivirus (FCV-F9) and murine norovirus (MNV-1), on model produce. Washed and air-dried lettuce (3 × 3 cm(2)) and jalapeno peppers (25-30 g) were inoculated with FCV-F9, MNV-1, or HAV at high (∼7 log10 PFU/ml) or low (∼5 log10 PFU/ml) titers, and treated with 0.25, 0.5, 1 mg/ml GSE or water for 30 s to 5 min. Treatments were stopped/diluted with cell-culture media containing 10% heat-inactivated fetal bovine serum and evaluated using plaque assays. At high titers, FCV-F9 was reduced by 2.33, 2.58, and 2.71 log10 PFU on lettuce; and 2.20, 2.74, and 3.05 log10 PFU on peppers after 1 min using 0.25, 0.50, and 1 mg/ml GSE, respectively. Low FCV-F9 titers could not be detected after 1 min at all three GSE concentrations. Low titer MNV-1 was reduced by 0.2-0.3 log10 PFU on lettuce and 0.8 log10 PFU on peppers, without reduction of high titer. GSE at 0.25-1 mg/ml after 1 min caused 0.7-1.1 and 1-1.3 log10 PFU reduction for high and low HAV titers, respectively on both commodities. Instrumental color analysis showed no significant differences between treated and untreated produce. GSE shows potential for foodborne viral reduction on produce as part of hurdle technologies.