Synergistic Effects of Combined Chlorine and Vitamin B-1 on the Reduction of Murine Norovirus-1 on the Oyster (Crassostrea gigas) Surface

Abstract

This study investigated the synergistic effects of combined chlorine (200, 500, 700, and 1000 ppm) and vitamin B-1 (1000, 2000, and 3000 ppm) on the murine norovirus-1 (MNV-1), a human norovirus (NoV) surrogate, on oyster surface. Vitamin B-1 slightly reduced MNV-1 (0.04-0.3 log-reduction), whereas chlorine significantly reduced MNV-1 (0.4-1.0 log-reduction). The combined chlorine and vitamin B-1 resulted in a 0.52-1.97 log-reduction of MNV-1. The synergistic reduction in the MNV titer was not dependent on the concentrations of chlorine and vitamin B-1, and it ranged between 0.08 and 1.03 log(10) PFU/mL. The largest synergistic reduction observed was for the combined 700 ppm chlorine and 1000 ppm vitamin B-1. The pH and mechanical texture of the oysters were not significantly changed by the combined 0-1000 ppm chlorine and 3000 ppm vitamin B-1. The overall sensory acceptability were significantly (P < 0.05) reduced in oysters treated with 1000 ppm chlorine and 3000 ppm vitamin B-1 than in those treated with 0-700 ppm chlorine and 3000 ppm vitamin B-1. This study suggests that the combined 700 ppm chlorine and 3000 ppm vitamin B-1 could potentially be used to reduce NoV on oyster surface without causing concomitant changes in the mechanical texture, pH, or sensory qualities of the oysters.