Inactivation of Salmonella enterica, Listeria monocytogenes and murine norovirus (MNV-1) on fresh strawberries by conventional and water-assisted ultraviolet light (UV-C)

• Published in: Postharvest biology and technology 2021-04, Vol.174, p.111447, Article 111447
• Main Authors: Ortiz-Solà, J., Abadias, I., Colàs-Medà, P., Anguera, M., Viñas, I.
• Format: Article
• Language: English
• Subjects: Berries; Chlorine; Chlorine alternative disinfection; Cross-contamination; Deactivation; Decontamination; Exposure; Food contamination; Food industry; Food processing industry; Fruit; Fruits; Inactivation; Infectivity; Irradiation; Lamps; Listeria; Listeria monocytogenes; Microorganisms; Radiation dosage; Salmonella; Salmonella enterica; Sanitization; Strawberries; Ultraviolet radiation; Wash water; Water pollution
• ISSN: 0925-5214; 1873-2356
• DOI: 10.1016/j.postharvbio.2020.111447

•WUVC reduced the population of pathogenic bacteria and enteric virus on strawberries.•At the same irradiation dose (1.3 kJ/m2),WUVC improved the efficacy of DUVC system.•For MNV-1, the increase in the irradiation dose did not affect their reduction.•WUVC was effective for wash water disinfection, enabling its recirculation.•The results obtained provide new tools to ensure the safety of strawberries. The efficacy of the water-assisted ultraviolet-C light (WUVC) strategy was evaluated as an alternative to chlorine sanitization and compared to ‘conventional’ dry technology (DUVC) for the inactivation of Salmonella enterica, Listeria monocytogenes and murine norovirus (MNV-1) on strawberries. Strawberries were washed in a laboratory scale prototype (LAB-UVC-Gama) consisting of a tank filled with water, equipped with 4 UV-C lamps emitting a dose of 0.6, 1.3, 3.2 and 6.3 kJ m−2. For DUVC, the same doses were used. Moreover, trials with the 4 lamps off with water, or with a chlorine solution (200 ppm, pH 6.5), were carried out as a control treatment. Reductions of artificially inoculated L. monocytogenes and S. enterica, and the infectivity of MNV-1 after WUVC treatments were comparable to those obtained with chlorine-wash, which were equivalent with all irradiation doses tested for all microorganisms studied (P < 0.05). The implementation of the WUVC strategy improved the DUVC system after 2-min exposure (1.3 kJ m−2), by 1.2 and 1.6 log for S. enterica and L. monocytogenes, respectively. At 3.2 kJ m-2 dose (5 min), WUVC enhanced the inactivation of S. enterica compared with control washing treatment by 1.5 log. After 10 min, pathogenic bacteria were reduced by > 4 log by WUVC treatment and chlorine sanitization. For MNV-1 reductions, we reported > 1.4 log TCID50 with 95 % certainty with the different treatments and exposure times after decontamination procedures. For MNV-1, the increase in the irradiation dose (kJ m−2) applied did not affect their reduction on strawberries. Moreover, WUVC light was effective at significantly reducing the microorganisms in wash water, avoiding cross-contamination and thus, allowing water recirculation. The results obtained in the present study provide new tools to ensure the safety of strawberries intended to be processed, contributing to affording a more innovative and sustainable future for the food industry. However, industry operation studies are needed to conclude that the treatments tested in the present study are a good a