Decontamination of Listeria innocua from fresh-cut broccoli using UV-C applied in water or peroxyacetic acid, and dry-pulsed light

The efficacy of two irradiation technologies: Ultraviolet-C light (UV-C), applied in water or in diluted peroxyacetic acid, and dry-pulsed light (PL) for the inactivation and growth inhibition of Listeria innocua in fresh-cut broccoli were evaluated. Water-assisted UV-C (WUV) (0.3 and 0.5 kJ/m2) reduced L. innocua initial populations by 1.7 and 2.4 log10 CFU/g, respectively; the latter dose also inhibited their growth for 8 d at 5 °C. Replacing water with 40 or 80 mg/L peroxyacetic acid did not improve this efficacy. Pulsed light (5, 10, 15, and 20 kJ/m2) showed no effect on native microbiota. Neither did 15 kJ/m2 PL inactivate L. innocua or inhibit its growth. Nonetheless, 24-h post-processing, PL (15 kJ/m2) increased total phenolic content by 25% in respect of chlorine-sanitation, and enhanced total antioxidant capacity by 12 and 18% compared to water and chlorine controls, respectively. Unlike dry-PL, WUV appears to be a suitable technology for controlling L. monocytogenes populations in fresh-cut broccoli.This work has been supported by the CERCA Programme / Generalitat de Catalunya, the Secretaria d'Universitats i Recerca / Departament d'Economia i Coneixement / Generalitat de Catalunya, and the European Social Fund (grant FI-DGR-2015-0004); the University of Lleida (Ref.127/2016); the Spanish Ministry of Economy, Industry, and Competitiveness (grant FJCI-2016-29541); and the European Social Fund (grant RYC-2016-19949).The authors thank INRA (UMR SQPOV, Avignon), in particular Veronique Broussole and Fréderic Carlin, for providing access to the facilities. Thanks are also given to CLARANOR s.a. for allowing the use of the PL equipment, and in particular to Alain Berberian, for his technical assistance

Impact of Pseudomonas graminis strain CPA-7 on respiration and ethylene production in fresh-cut ‘Golden delicious’ apple according to the maturity stage and the preservation strategy

The effect of the biocontrol agent (BCA) Pseudomonas graminis CPA-7 on the accumulation of CO2 and ethylene (C2H4) in fresh-cut apples at two maturity stages was evaluated in refrigerated conditions. Factors involved in the preservation strategy applied upon commercial conditions such as the antioxidant (AOX) treatment and the storage system were included in the analysis. Regardless of the maturity stage, the BCA reduced C2H4 levels within the MAP atmosphere in AOX-untreated apples wedges, by 29 and 43% in immature and mature apples, respectively. Nevertheless, the addition of ascorbate as antioxidant counteracted this effect. In vitro tests suggested that the reduction of C2H4 levels was not associated to the uptake of this molecule by CPA-7. Interestingly, in non-inoculated samples AOX treatment showed contradictory effects on C2H4 production in MAP conditions by significantly reducing C2H4 levels in immature apples (by 23%) while increasing it in mature ones (by 40%). Similarly, CPA-7 had opposite effects on the CO2 accumulation pattern depending on the storage system or the fruit maturity stage. In this sense, CPA-7 was associated to a higher fruit respiratory activity at an advanced maturity stage yet without inducing the fruit fermentative metabolism or altering the fruit quality during a week of refrigerated storage. Overall, these results show that CPA-7 may contribute to the maintenance of the microbiological and physicochemical quality of fresh-cut apple by modulating the fruit ethylene production and/or respiration.This work has been supported by the CERCA Programme/Generalitat de Catalunya and by the Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya (grant FI-DGR-2015-0004). Thanks are given to Iolanda Nicolau, Silvia Villaró, Marina Anguera and Dr. Gloria Bobo for their technical support

Pseudomonas graminis strain CPA-7 differentially modulates the oxidative response in fresh-cut ‘Golden delicious’ apple depending on the storage conditions

The oxidative response in fresh-cut antioxidant-treated‘Golden delicious’apples during chilling storage wasdifferentially modified by the biopreservative bacteriumPseudomonas graminisCPA-7 depending on the storageconditions (passive modified atmosphere packaging (MAP) or air). Results showed that inoculation with CPA-7had no influence on fruit quality parameters in any of the conditions tested. During thefirst 24 h both in air andin MAP, ascorbate peroxidase (APX) activity triplicated the initial level in response to CPA-7, reaching up to 4-fold the activity of non-inoculated fruit (control). From 24 h of storage in MAP, polyphenol oxidase (PPO)activity was sharply enhanced in response to CPA-7 attaining values up to 8-fold higher than that of the controlat the end of the experiment, yet it was not paired to an increase in browning incidence. Concomitantly, at 24 hof storage in MAP, CPA-7 suppressed peroxidase (POX) and catalase (CAT) activities. Subsequently, after 3 d insuch conditions, superoxide dismutase (SOD) and PPO activities were almost duplicated in the presence of CPA-7compared to the control. On the other hand, when stored in air, POX showed a biphasic induction in response toCPA-7 after 1 d and 6 d of incubation. On day 6, this enzyme duplicated its activity in inoculated samplescompared to the control regardless of storage conditions. Inoculation with CPA-7 led to the slowdown of thedecline of antioxidant capacity in air, which contrasted with the response upon MAP conditions. These resultssuggest that CPA-7 may trigger the activation of the fruit defense-response thereby mitigating its oxidativedamage. Such activation may play a role as a putative biocontrol mechanism against foodborne pathogen in-fections.info:eu-repo/semantics/acceptedVersio

Effects of thermal and non-thermal processing of cruciferous vegetables on glucosinolates and its derived forms

Brassica vegetables, which include broccoli, kale, cauliflower, and Brussel sprouts, are known for their high glucosinolate content. Glucosinolates and their derived forms namely isothiocyanates are of special interest in the pharmaceutical and food industries due to their antimicrobial, neuroprotective, and anticarcinogenic properties. These compounds are water soluble and heat-sensitive and have been proved to be heavily lost during thermal processing. In addition, previous studies suggested that novel non-thermal technologies such as high pressure processing, pulsed electric fields, or ultraviolet irradiation can affect the glucosinolate content of cruciferous vegetables. The objective of this paper was to review current knowledge about the effects of both thermal and non-thermal processing technologies on the content of glucosinolates and their derived forms in brassica vegetables. This paper also highlights the importance of the incorporation of brassica vegetables into our diet for their health-promoting properties beyond their anticarcinogenic activities.info:eu-repo/semantics/acceptedVersio

Decontamination of fresh-cut broccoli with a water–assisted UV-C technology and its combination with peroxyacetic acid

The effectiveness of a water-assisted UV-C (WUV) technology for the decontamination of fresh-cut broccoli from conventional and organic agricultural practices was evaluated as an alternative to chlorine sanitation. Several WUV doses (0.3–1.8 kJ m−2) were tested alone or combined with peroxyacetic acid (PAA). Results showed that 0.5 kJ m−2 was sufficient to reduce natural total aerobic mesophilic microorganisms by 2 log10 in conventional broccoli without negative consequences on the physical quality. However, in order to achieve the same effect on organic broccoli, a combined application of at least 0.3 kJ m−2 and 50 mg L−1 PAA was required. Total antioxidant capacity (TAC) was enhanced by 42, 90 and 81% in conventional broccoli 24 h after treatment with 0.3, 0.5 and 1.8 kJ m−2, respectively, compared to water-control. A similar trend was observed in organic broccoli, although the increase in TAC (by 22%) compared to the water-control was only significant when a dose of 1.8 kJ m−2 was used. Similarly, 0.5 kJ m−2 enhanced the sulforaphane content in conventional broccoli by 1.5 and 4-fold compared to water and chlorine-controls, respectively. WUV is a promising alternative technology to improve the microbiological and nutritional quality of fresh-cut broccoli.This work has been supported by the CERCA Programme/Generalitat de Catalunya and by the Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement/ Generalitat de Catalunya (grant FI-DGR-2015-0004); by the Spanish Ministry of Economy, Industry, and Competitiveness (grant FJCI-2016-29541); and the European Social Fund (grant RYC-2016-19949). Thanks are also given to Ariadna Bademunt and Ismael Povedano for their technical assistance

Assessing water-assisted UV-C light and its combination with peroxyacetic acid and Pseudomonas graminis CPA-7 for the inactivation and inhibition of Listeria monocytogenes and Salmonella enterica in fresh-cut 'Iceberg' lettuce and baby spinach leaves

The effectiveness of ultraviolet C light (UV-C) delivered in water (WUV) or in peroxyacetic acid (PAA) for theinactivation and inhibition ofL. monocytogenesandS. entericain ready-to-eat'Iceberg lettuce'and baby spinachleaves, was evaluated throughout chilled storage in modified atmosphere packaging (MAP). The inhibition ofpathogen's growth by sequential pretreatments with UV-C in PAA and then biocontrol usingPseudomonas gra-minisCPA-7 was assessed during MAP storage at 5 °C and upon a breakage of the cold-storage chain. In fresh-cutlettuce, 0 1 kJ/m2UV-C, in water or in 40 mg/L PAA, inactivated both pathogens by up to 2.1 ± 0.7 log10,which improved the efficacy of water-washing by up to 1.9 log10and showed bacteriostatic effects on bothpathogens. In baby spinach leaves, the combination of 0 3 kJ/m2UV-C and 40 mg/L PAA reducedS. entericaandL. monocytogenespopulations by 1.4 ± 0.2 and 2.2 ± 0.3 log10respectively, which improved water-washing by0.8 ± 0.2 log10. Combined treatments (0.1 or 0 3 kJ/m2WUV and 40 mg/L PAA) inactivated both pathogens inthe process solution from lettuce or spinach single sanitation, respectively. Pretreating lettuce with UV-C in PAAreducedL. monocytogenesandS. enterica's growth by up to 0.9 ± 0.1 log10with respect to the PAA-pretreatedcontrol after 6 d at 5 °C in MAP. Upon a cold-chain breakage, CPA-7 preventedS. entericagrowth in PAA-pretreated lettuce, whereas showed no effect onL. monocytogenesin any of both matrices. Low-dose UV-C in PAAis a suitable preservation strategy for improving the safety of ready-to-eat leafy greens and reducing the risk ofcross contamination.This work has been supported the CERCA Programme / Generalitat de Catalunya, Spain; the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement / Generalitat de Catalunya; the European Social Fund (grant FI-DGR-2015-0004); and the Spanish Ministry of Economy, Industry, and Competitiveness (National Project of the Spanish Foundation for Science and Technology: FECYT CC/2013105 (2013-16) and grant: RYC-2016-19949). Thanks are given to Marina Anguera for her technical assistance

Bioconservación frente a patógenos de transmisión alimentaria en frutas y hortalizas mínimamente procesadas

The production and consumption of minimally pro­cessed fruits and vegetables have increased in recent years, which has contributed to increasing the foodborne illnesses associated with the consumption of fresh produce. This is because current disinfection methods used in the fresh-cut industry are not enough to guarantee the microbial safety of the final products, and minimally processed produce does not receive any other treatment capable of eliminating all patho­gens before consumption. Therefore, alternative strategies to reduce pathogenic and spoilage microorganisms are needed. Biopreservation, using microorganisms or their metabolites, is an alternative that, in combination with current practices, could reduce or prevent pathogenic growth in minimally processed produce, improving their microbiological quality. This paper re­views the most relevant results on biopreservation of minimally processed fruits and vegetables.El aumento en la producción y consumo de frutas y hortalizas mínimamente procesadas de los últimos años ha con­tribuido a incrementar las toxiinfecciones alimentarias asociadas al consumo de productos vegetales frescos. Esto es debido a que los tratamientos desinfectantes llevados a cabo actualmente por industria de IV gama son insuficientes para garantizar la seguridad microbiológica de los productos finales, y además estos no reciben ningún tratamiento capaz de eliminar todos los patógenos antes de su consumo. Por lo tanto, es necesario utilizar estrategias al­ternativas para reducir los microorganismos patógenos y alteran­tes en frutas y hortalizas. La bioconservación, mediante el uso de microorganismos o sus metabolitos, es una alternativa que, en combinación con las prácticas habituales, puede reducir o prevenir el crecimiento de patógenos en productos mínimamente procesa­dos, mejorando su calidad microbiológica. En este artículo se pre­sentan los resultados más relevantes sobre la bioconservación de frutas y hortalizas mínimamente procesadas

Novel preservation strategies for microbial decontamination of fresh-cut fruit and vegetables

La bioconservació, així com els mètodes químics i físics, es van avaluar per controlar patògens de transmissió alimentària en productes vegetals mínimament processats. La investigació dels mecanismes d'acció de Pseudomonas graminis CPA-7 va revelar que la seva activitat bioconservadora s'exerceix a través de la combinació de la competència, el deteriorament de les capacitats de colonització dels patògens i l'activació de la resposta defensiva de l'hoste vegetal. Com enfocament físic, es va avaluar la llum ultraviolada C acoblada a immersió (WUV), en aigua i en àcid peroxiacètic (PAA), per descontaminar vegetals mínimament processats. WUV va reduir la microbiota nativa i els patògens inoculats del bròquil i de verdures de fulla, així com va millorar les propietats bioactives del bròquil. Una altra tecnologia física avaluada per a la descontaminació del bròquil va ser la llum polsada, sense mostrar idoneïtat. Finalment, es va avaluar la combinació de WUV, PAA i CPA-7 per a la descontaminació de verdures de fulla, millorant sinergísticament l'efecte inhibidor sobre el creixement de Salmonella enterica depenent de la matriu. En resum, la biopreservació i l’aplicació de WUV són tecnologies prometedores, alternatives al clor, que actuen a través de múltiples mecanismes i es poden implementar per millorar la qualitat microbiològica i les propietats bioactives dels productes mínimament processats.La bioconservación, así como métodos químicos y físicos, se evaluaron para controlar patógenos transmitidos por los alimentos en productos vegetales mínimamente procesados. La investigación de los mecanismos de acción de Pseudomonas graminis (CPA-7) reveló que su actividad bioconservadora se ejerce a través de la combinación de la competencia, del deterioro de las capacidades de colonización de los patógenos y de la activación de la respuesta defensiva del hospedante vegetal. Como enfoque físico, se evaluó la luz ultravioleta C acoplada a inmersión (WUV), en agua y en ácido peroxiacético (PAA), para descontaminar vegetales mínimamente procesados. WUV redujo la microbiota nativa y los patógenos inoculados en brócoli y verduras de hoja, y además mejoró las propiedades bioactivas del brócoli. Otra tecnología física: la luz pulsada, se ensayó para la descontaminación del brócoli sin mostrar idoneidad. Finalmente, se evaluó la combinación de WUV, PAA y CPA-7 para la descontaminación de verduras de hoja. Esta estrategia mejoró sinergísticamente el efecto inhibidor de CPA-7 sobre el crecimiento de Salmonella enterica dependiendo de la matriz. En resumen, la biopreservación y la aplicación de WUV son tecnologías prometedoras, alternativas al cloro, que actúan a través de múltiples mecanismos y que pueden implementarse para mejorar la calidad microbiológica y bioactiva de los vegetales mínimamente procesados.Biopreservation as well as chemical and physical methods were essayed to control foodborne pathogens in fresh-cut fruit and vegetables. The investigation of the action mechanisms of Pseudomonas graminis (CPA-7) revealed that its biopreservative activity is exerted through the combination of competition, the impairment of pathogen’s colonization abilities and the activation of the plant-host's defense response. As a physical approach, water-assisted UV-C (WUV) was evaluated, alone and combined with peroxyacetic acid (PAA), for the decontamination of fresh-cut vegetables. It was effective for reducing native microbiota and inoculated pathogens in fresh-cut broccoli and leafy greens, as well as for enhancing the bioactive content in broccoli. Another physical technology: pulsed light was essayed for decontamination of broccoli, showing no suitability. Finally, the combination of WUV, PAA and CPA-7 was evaluated for decontamination of leafy greens, showing a synergistic enhancement of the inhibitory effect of CPA-7 on S. enterica growth depending on the matrix. In summary, biopreservation and WUV are promising alternative-to-chlorine technologies, which act via multiple mechanisms, and can be implemented to improve the microbiological and nutritional quality of fresh-cut produce