Water UV-C treatment alone or in combination with peracetic acid: A technology to maintain safety and quality of strawberries

Abstract

Disinfection of fruits is one of the most important steps since they are going to be eaten fresh-or minimally-processed. This step affects quality, safety, and shelf-life of the product. Despite being a common sanitizer in the fruit industry, chlorine may react with organic matter leading to the formation of toxic by-products. Alternative sustainable disinfection strategies to chlorine are under study to minimize environmental and human health impact. Water-assisted UV-C light (WUV-C) is proposed here as an alternative sanitizing method for strawberries. In this study, strawberries were washed for 1 or 5 min in a tank with 2 or 4 lamps on, each emitting UV-C light at 17.2 W/cm 2 , or in a chlorine solution (200 ppm, pH 6.5). Moreover, trials with 4 lamps on, together with a washing solution consisting on peracetic acid at 40 or 80 ppm, were carried out. Overall, quality and nutritional parameters of strawberries after treatments were maintained. Changes in color were not noticeable and fruits did not lose firmness. No major changes were observed in antioxidant activity, organic acid, anthocyanin, vitamin C, and total phenolic content. Yeasts and molds were not affected by the WUV-C treatment, and 5 min were needed to significantly reduce total aerobic mesophylls population. However, reductions of artificially inoculated Listeria innocua and Salmonella Typhimurium after WUV-C treatments were comparable to those obtained with chlorine-wash, which were 3.0 log CFU / g. Moreover, WUV-C light was effective to minimize microorganisms remaining in washing water, avoiding cross-contamination and thus, allowing water recirculation. This effect was improved when combining the action of UV-C light with peracetic acid, showing the suitability of this combined treatment, understood as an alternative to chlorine sanitation, for sanitizing strawberries and keeping the populations of pathogenic bacteria in washing water lower than 0.6 ± 0.1 log CFU / mL.

Exploring thermosonication as non-chemical disinfection technology for strawberries

“…Values of TPC and TAC of strawberries used for the treatments are in accordance for those already reported in strawberries from the same origin [19,41]. In the present study, TAC and TPC values did not overcome major changes after heat treatment with or without sonication.…”

An innovative water-assisted UV-C disinfection system to improve the safety of strawberries frozen under cryogenic conditions

“…However, there were no significant differences between them (P > 0.05). Therefore, results confirmed the effectiveness of the different washing treatments, since the WUVC and the combination treatment (WUVC+PA) are comparable to disinfection with free chlorine (P > 0.05), allowing the inhibition of the principal foodborne bacterial pathogens on fresh strawberries after the different decontamination methodologies tested during 2-min exposure (Nicolau-Lapeña et al, 2020;Ortiz-Solà et al, 2020).…”

“…For each sanitization treatment, 20 strawberries (25-g each, approximately) were used. Samples were washed for 2 min using the WUVC equipment in combination with 40-mg/L (ppm) peracetic acid (PA) (WUVC+PA), since previous work reported that this combination significantly reduced pathogenic microorganisms on strawberries (Nicolau-Lapeña et al, 2020). Moreover, WUVC alone and 200 ppm of sodium hypochlorite (NaClO) (pH 6.5) were also added as control treatments in the same equipment commented above.…”

“…Other authors have studied the combination of alternative disinfectants (chloride dioxide, lactic acid and ozone) with freezing for the reduction of Salmonella, L. monocytogenes and E. coli on blueberries (Bridges et al 2019;Tadepalli et al, 2018). Previously, our research group has studied the efficacy of a water-assisted short-wave ultraviolet (WUVC) technology, alone or combined with peracetic acid (PA), for the reduction of natural microbiota, L. monocytogenes and S. enterica in fresh strawberries (Nicolau-Lapeña et al, 2020;Ortiz-Solà et al, 2020;Ortiz-Solà et al, 2021), obtaining promising results and maintaining the fruit quality. To our knowledge, this combination technology has not been previously tested against enteric viruses on frozen strawberry produce.…”

Whole‐room ultraviolet sanitization as a method for the site‐level treatment ofPseudogymnoascus destructans

“…Ultraviolet radiation is a common sanitization method in medical settings and the heating, ventilation and air conditioning (HVAC) industry (Masse et al, 2018; Yang et al, 2018). It also has been effectively employed in water treatment application (Dotson et al, 2012; Li et al, 2017; Li et al, 2019), as well as food production activities (Garvey & Rowan, 2019; Nicolau‐Lapeña et al, 2020). Importantly, UV‐C radiation units designed to treat entire rooms are already commercially available.…”