Evaluation of water‐assisted UV‐C light and its additive effect with peracetic acid for the inactivation of Listeria monocytogenes, Salmonella enterica and murine norovirus on whole and fresh‐cut strawberries during shelf‐life

Abstract

BACKGROUND:The purpose of the present study was to examine the inactivation of Salmonella enterica (50 ∼L; 10 9 CFU g −1 ), Listeria monocytogenes (50 ∼L; 10 9 CFU g −1 ), and murine norovirus (MNV-1; 50 ∼L; 10 7 50% tissue culture infectious dose (TCID 50 ) mL −1 ) on whole and fresh-cut strawberries after 2 min disinfection treatments (water (H 2 O), chlorine 200 mg L −1 (NaClO), water-assisted ultraviolet-C (UV-C) (WUV), and the combination WUV and 40 mg L −1 of PA (WUV + PA)) in a water tank (15 L) equipped with 4 UV-C lamps (17.2 W each), and after 7 days of cold storage (4 and 10 °C). For MNV-1, dry UV-C treatment (DUV) was also tested. For all UV-C treatments, an irradiation dose of 1.3 kJ m −2 was used.RESULTS: When strawberries were washed with WUV, L. monocytogenes and S. enterica were reduced by 2.8 and 2.2 log CFU g −1 , respectively. The addition of 40 mg L −1 of PA to WUV (WUV + PA) increased the reduction range of L. monocytogenes and S. enterica by 1.9 and 0.8 log, respectively. Regarding the wash water, no pathogens were recovered after the WUV + PA treatment (detection limit 50 CFU mL −1 ). Depending on storage conditions (7 days at 4 or 10 °C), reductions observed were 0.5 to 2.0 log for S. enterica and 0.5 to 3.0 log for L. monocytogenes. The reductions in MNV-1 titer after disinfection treatments ranged from 1.3 to 1.7 log. No significant differences between storage conditions were observed for MNV-1: titers did not decline or were reduced up to 0.3 log after 7 days of cold storage.CONCLUSION: The three-way action for disinfecting strawberries by UV-C irradiation and PA, plus the physical removal of the microorganisms by agitated water, are effective against foodborne pathogens on strawberries and water wash. During storage, WUV had a larger impact on the inactivation kinetics of S. enterica. Storage had little impact on MNV-1 inactivation.

Ultraviolet-C Light and Peracetic Acid Extend the Shelf Life of Fresh and Frozen Strawberries

“…Reductions in bacterial pathogens were demonstrated by [10] in strawberries by using this combination (WUVPA). However, the decrease in the counts of natural occurring microbiota in strawberries found in that study was lower compared to that of artificially inoculated L. monocytogenes and S. enterica with the same sanitizing treatment [11]. De Sao Jose and Vanetti [19] reported a 3 log CFU g −1 decrease in Y&M population after washing strawberries with 40 mg L −1 PA.…”

“…Moreover, in previous studies by our group, the combination of WUV-C and PA at 40 mg L −1 reduced artificially inoculated norovirus in strawberries reaching to 2 log Tissue Culture Inhibition Dose at 50% or TCID 50 g −1 . L. monocytogenes and S. enterica artificially inoculated in strawberry were also reduced reaching to 4.5 and 2.8 log CFU g −1 after the washing treatments [11].…”

“…The effect of water-assisted UV-C (WUV-C) combined with 40 mg L −1 peracetic acid (PA) on the shelf life of strawberries was studied in two formats: fresh and frozen. Treatments were conducted in the UV-C water-assisted (WUV-C) equipment LAB-UVC-Gama (UVC-Consulting Peschl España, Castellón, Spain), as already described by Nicolau-Lapeña et al [10] and Ortiz-Solà et al [11]. Before the experiment, the 4 UV-C lamps were preheated for 10 min.…”

UV-C Light: A Promising Preservation Technology for Vegetable-Based Nonsolid Food Products

“…UV-C light can be used to sanitize water used in food processing and production as well as help prevent the growth of harmful bacteria and other microorganisms in municipal water supply systems [53,55]. Additionally, UV-C light has been used to extend the shelf life of fresh, minimally processed, and liquid foods by reducing the microbial load and helping to prevent spoilage [12,[56][57][58][59][60].…”