Evaluation of inactivating norovirus, hepatitis A, and Listeria monocytogenes on raspberries by sanitizer spray

Abstract

Reducing the risk of contamination with foodborne pathogens is paramount in maintaining safety of produce. The raspberry industry uses chlorine spray as a control measure before conveying freshly picked red raspberries into individually quick frozen units. However, the efficacy of sanitizer spray treatment to inactivate norovirus, hepatitis A virus (HAV), and Listeria monocytogenes on raspberries has not been characterized. In this study, a laboratory-scale spray bar device was fabricated to simulate industrial settings. Fresh raspberries were spot inoculated with murine norovirus (MNV, a norovirus surrogate), HAV, or L. monocytogenes and sprayed with 50 ppm of chlorine or 80 ppm of peroxyacetic acid (PAA). Surviving pathogens were enumerated after spray or postspray frozen storage at-20°C for 1 and 24 h. Chlorine and PAA spray treatments reduced MNV and L. monocytogenes from raspberries by 0.2 and 0.6 log but had no effect on HAV. During frozen storage after spray treatment, the residual PAA on the fruit surfaces further reduced MNVand L. monocytogenes, achieving a total reduction of approximately 0.6 and 3.0 log, respectively. HAV levels were not affected by frozen storage after PAA or chlorine spray treatment. The findings were supported by the sanitizer decay results showing that PAA decayed more slowly than active chlorine on raspberry surfaces. Submerging washes conducted as comparisons showed higher reduction of pathogens from raspberry surfaces than similar respective sanitizer spray treatments. The results suggest that PAA could contribute to raspberry postharvest sanitation, aiding in risk reduction of pathogen contamination prior to entering an individually quick frozen unit. HIGHLIGHTS • Chlorine and PAA spray reduced MNV and L. monocytogenes from raspberries by < 1.0 log. • Residual PAA on raspberries further reduced MNV and Listeria during postspray frozen storage. • PAA decayed more slowly than active chlorine on raspberry surfaces. • The data suggest that PAA could aid in risk reduction of pathogens on raspberries.