Chlorine treatment to inactivate norovirus on food contact surfaces.

This study was conducted to determine the concentration and optimal treatment time of chlorine for reducing feline calicivirus (FCV) and murine norovirus (MNV) as surrogates of norovirus (NoV) on stainless steel surfaces and to develop a predictive inactivation method using a response surface methodology. The reduction levels of FCV VR-782 and MNV on stainless steel surfaces after treatment with various concentrations of chlorine (0 to 5,000 ppm) for various times (0 to 5 min) were measured. The reduction values of both FCV and MNV on stainless steel surfaces after 5,000 ppm of chlorine treatment for 5 min were 5.20 TCID(50) per coupon. The predictive results obtained by central composite design were analyzed by standard analysis of variance. The application of multiple regression analysis was related to the following polynomial equations: (i) FCV (log TCID(50) per coupon) = -0.3714 + 0.8362x(1) + 0.0011x(2) + 0.0001x(1)x(2) - 0.1143x(2)(1) -0.0001x(2)(2) (x(1), time; x(2), concentration) and (ii) MNV (log TCID(50) per coupon) = + 0.0471 + 0.0807x(1) + 0.0011x(2) + 0.0001x(1)x(2) -0.0910x(2)(1) -0.0001x(2)(2) (x(1), time; x(2), concentration). It was concluded that these polynomial equation models of reduction of FCV and MNV could be used to determine the minimum concentration of chlorine and exposure times to control human NoV on food contact surfaces.