Exploring thermosonication as non‑chemical disinfection technology for strawberries

The scope of this work was to study the efcacy of the combination of sonication at 35 or 130 kHz with three temperature treatments: 20, 50 and 55 ºC, on the population of artifcially inoculated Listeria innocua in strawberries, and on their overall quality. Prior in vitro results showed that temperature was the main factor in decreasing L. innocua population: a maximum of 3.8 log reductions was obtained with sonication at 130 kHz and 55 ºC for 15 min Treatments combining—or not—sonication at 130 kHz with mild temperatures (50 and 55 ºC) for 5 or 10 min were able to decrease about 3 log units of artifcially inoculated L. innocua in strawberries and about 2 log units of total aerobic mesophilic and yeasts and molds populations naturally occurring in strawberries. Thermosonication treatments did not exert a detrimental impact on fruit quality, except for those at the higher temperatures and times, which caused a change in color to more purplish and a little softening of the strawberries, which were proposed to be assessed for further processing other than fresh commercialization. Overall, the impact of sonication in fresh strawberries needs to be further investigated to fnd the adequate conditions to enhance the efects of temperature itself.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. 'Ministerio de Economia, Industria y Competitividad' was the financial support of the project AGL2016-78086-R and the CERCA Programme of the 'Generalitat de Catalunya' (Spain). I. Nicolau-Lapena is in receipt of a predoctoral grant awarded by the 'Ministerio de Economia, Industria y Competitividad' (grant number BES-2017-079779). Dr. I. Aguilo-Aguayo thanks the National Programme for the Promotion of Talent and Its Employability of the 'Ministerio de Economia, Industria y Competitividad' of the Spanish Government and the European Social Fund for her Postdoctoral Senior Grant `Ramon y Cajal' (RYC-2016-2019 949)

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

The purpose of the present study was to examine the inactivation of Salmonella enterica (50 μL; 109 CFU g−1), Listeria monocytogenes (50 μL; 109 CFU g−1), and murine norovirus (MNV-1; 50 μL; 107 50% tissue culture infectious dose (TCID50) mL−1) on whole and fresh-cut strawberries after 2 min disinfection treatments (water (H2O), 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.The authors are grateful to the Spanish government (Ministerio deEconomía y Competitividad, research project AGL2016-78086-R)and the Centres de Recerca de Catalunya (CERCA) Programmeof‘Generalitat de Catalunya’for itsfinancial support. J. Ortiz-Solàthanks the University of Lleida for its PhD grant (BOU186-243/2017 UdL) and M. Anguera thanks them for their techni-cal support. I. Nicolau-Lapeña is in receipt of a predoctoral grantawarded by the‘Ministerio de Economía, Industria y Competitivi-dad’(grant number BES-2017-079779). The authors gratefullyacknowledged the assistance of Gloria Sánchez and Susana Guixfor teaching them the methodologies related to MNV-1 andRAW 264.7 assays

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

BACKGROUND: The purpose of the present study was to examine the inactivation of Salmonella enterica (50 ∼L; 109 CFU g−1), Listeria monocytogenes (50 ∼L; 109 CFU g−1), and murine norovirus (MNV-1; 50 ∼L; 107 50% tissue culture infectious dose (TCID50) mL−1) on whole and fresh-cut strawberries after 2 min disinfection treatments (water (H2O), 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.info:eu-repo/semantics/publishedVersio

Ultrasound processing alone or in combination with other chemical or physical treatments as a safety and quality preservation strategy of fresh and processed fruits and vegetables: a review

Ultrasound (US) processing has emerged as a novel food preservation technology. This strategy has proved antimicrobial effects due to cavitation, which is the formation, growth, and collapse of bubbles that generate a localized mechanical and chemical energy. This technology can be applied by water so introducing it in the washing step to obtain safe fresh or fresh-cut products could be promising. The current review provides an overview of the current knowledge and recent findings on the use of US, alone or in combination with other mild physical technologies or chemical agents, to reduce microbial loads, and to better retain their quality attributes including color and texture, as well as the content of bioactive compounds such as antioxidant, phenolic compounds, or vitamins of minimally processed fruits and vegetables. As the effects of US depends on several factors related with treatment parameters, target microorganism, and matrix characteristics, further research efforts should be directed on optimizing US processes in accordance with their further application.info:eu-repo/semantics/acceptedVersio

Ultrasound processing alone or in combination with other chemical or physical treatments as a safety and quality preservation strategy of fresh and processed fruits and vegetables: a review

Ultrasound (US) processing has emerged as a novel food preservation technology. This strategy has proved antimicrobial effects due to cavitation, which is the formation, growth, and collapse of bubbles that generate a localized mechanical and chemical energy. This technology can be applied by water so introducing it in the washing step to obtain safe fresh or fresh-cut products could be promising. The current review provides an overview of the current knowledge and recent findings on the use of US, alone or in combination with other mild physical technologies or chemical agents, to reduce microbial loads, and to better retain their quality attributes including color and texture, as well as the content of bioactive compounds such as antioxidant, phenolic compounds, or vitamins of minimally processed fruits and vegetables. As the effects of US depends on several factors related with treatment parameters, target microorganism, and matrix characteristics, further research efforts should be directed on optimizing US processes in accordance with their further application.info:eu-repo/semantics/acceptedVersio

Strawberry sanitization by peracetic acid washing and its effect on fruit quality

The risk posed by outbreaks associated with strawberries together with the safety issues of by-products from chlorine disinfection in the fruit industry has led to a search for alternative sanitizers. The disinfection capacity of peracetic acid (PA) at three concentrations (20, 40 and 80 ppm) and washing times (1 and 2 min) was compared to sodium hypochlorite (200 ppm) (NaClO) treatments and a water control, and its influence on the physico-chemical, biochemical and nutritional quality of strawberries was also studied. Counts on total aerobic mesophilic microorganisms were comparable between NaClO and PA. For yeasts and molds, only NaClO and 80 ppm PA reduced contamination in washing water, but no differences wereobserved in strawberries. Artificially inoculated L. innocua was reduced by at least 4 log cfu/g in strawberry by all the PA treatments, except at 20 ppm PA for 1 min. Total soluble solids, pH, titratable acidity, antioxidant activity and total phenolic content values were maintained after all treatments. Only anthocyanin content was affected. Treatments of 20 and 40 ppm PA did not significantly affect fruit color, and there were no losses on strawberry firmness. PA, as a GRAS substance that has shown potential to reduce microorganisms present in strawberries without any major physicochemical or sensorial alteration, could be a suitable alternative to chlorine disinfection.info:eu-repo/semantics/acceptedVersio

Combination of sonication with anti-browning treatments as a strategy to increase the shelf life of fresh-cut potatoe (cv. Monalisa)

Abstract. Two antioxidant solutions, a patented mixture based on vitamin C and other compounds (Natureseal®, MV) and green tea extract (GT), were proposed to prevent browning in sliced potatoes. Combination with ultrasound (US) at two frequencies (35 and 130 kHz) was also evaluated, but no significant enhancement of the effects was detected with US. In MV-treated samples, respiration rate and dry matter (19.7%) were higher than they were in the control (CK) (17.3%) or GT-treated samples (16.8%). Neither membrane integrity nor malondialdehyde content was significantly affected by the addition of MV or GT, but in MV samples the antioxidant activity was increased sixfold at the beginning of the storage (39.1 mmol ascorbic acid equivalents/kg), but decreased after 9 days. A yellowish coloration on the surface of GT samples (L*a*b* values being 68.3, −6.4, and 25.3, respectively), attributed to the coloration of the tea concentrate, was observed. In the conditions studied, GT was not able to delay browning in potatoe slices. In contrast, MV solution preserved the original color of the sliced potatoes (69.6, −6.7, and 27.7 for L*a*b*, respectively), during the 9-day storage at 4°C. Novelty Impact Statement. Sulfites are used as an additive to maintain food color, shelf life, and prevent the growth of fungi or bacteria. However, they are considered as allergenic substances. The study proves the efficacy of vitamin C as a substitute to sulfites to preserve fresh-cut potatoes and delay their browning.This work was financially supported by the Spanish “Ministerio de Educación, Economía y Competitividad” [Ramón y Cajal Program, RYC-2016-19949 (I. Aguiló-Aguayo), and Predoctoral grant, BES-2017-079779 (I. Nicolau-Lapeña)]. This work was supported by the CERCA Programme of Generalitat de Catalunya