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

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.This work was financially supported by Spanish ‘Ministerio de Educación, Economía y Cultura’ [FRESAFE Project AGL 2016-78086-R, Ramón y Cajal Program, RYC-2016-19949 (I. Aguiló-Aguayo), Predoctoral grant, BES-2017-079779 (I. Nicolau-Lapeña) and Juan de la Cierva grant, FJCI-2016-29541 (T. Lafarga)]

Combination of ferulic acid with Aloe vera gel or alginate coatings for shelf-life prolongation of fresh-cut apples

Weight loss, microbial spoilage and enzymatic browning are the main quality-determining processes which limit the shelf-life of fresh-cut apples. In this study, two edible coatings based on Aloe vera gel (AV) and sodium alginate cross-linked with calcium lactate (AC), with the addition of 10 mg/mL ferulic acid (FA) as a functional ingredient, were developed in order to prolong the quality and safety of fresh-cut apple discs. Texture parameters, pH and Brix values and water activity did not undergo relevant changes related to the treatments. Except for weight loss, which was significantly lower for the coated samples, the addition of FA was found to be the most relevant factor for the other investigated parameters, including the total phenolic content and the antioxidant activity measured by ferric reducing antioxidant power (FRAP). Browning was delayed by the addition of FA and also by the AV coating, while non-coated and alginate coated samples showed the highest values in early stages. Although no effect on Saccharomyces cerevisiae was observed, FA treatments and alginate were effective in reducing Listeria monocytogenes populations by 2.3 ± 0.4 log CFU / g, which contributes to an enhanced product safety.The Agrimax project received funding from the Bio-based Industries Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 720719. This work was also supported by the CERCA Programme of Generalitat de Catalunya. 720719. Nicolau-Lapeña is in receipt of a predoctoral grant awarded by the Spanish Ministry of Economy, Industry and Competitiveness (BES-2017-079779). Dr. I. Aguiló-Aguayo thanks the National Programme for the Promotion of Talent and Its Employability of the Spanish Ministry of Economy, Industry and Competitiveness, and the European Social Fund for her Postdoctoral Senior Grant ‘Ramon y Cajal’ (RYC-2016-2019 949)

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

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/cm2, 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.The authors are thankful to ‘Ministerio de Economía, Industria y Competitividad’ for the financial support of the project AGL2016-78086-R. I. Nicolau-Lapeña is in receipt of a predoctoral grant awarded by the ‘Ministerio de Economía, Industria y Competitividad’ (grant number BES-2017-079779). Dr. I. Aguiló-Aguayo thanks the National Programme for the Promotion of Talent and Its Employability of the ‘Ministerio de Economía, Industria y Competitividad’ of the Spanish Government and the European Social Fund for her Postdoctoral Senior Grant ‘Ramon y Cajal’ (RYC-2016-2019 949)

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

Pathogenic potential of the surviving Salmonella Enteritidis on strawberries after disinfection treatments based on ultraviolet-C light and peracetic acid

Fresh fruits, especially strawberries, are usually consumed raw without any step to ensure their food safety. Salmonella enterica is one of the most important etiologic agents for foodborne diseases throughout the world and its ability to respond to some stress responses makes it even more dangerous. In the present investigation, we study the survival of S. Enteritidis (CECT-4300) on strawberries after 2-min of various disinfection steps (NaClO (200 ppm), peracetic acid (PAA; 40 ppm), water-assisted UV-C (WUV-C), and the combination WUV-C and 40 ppm of PAA (WUV-C + PAA)) and after 5 days of cold storage (4 °C). Moreover, the pathogenic potential of the surviving bacteria, such as the ability to survive throughout the gastrointestinal tract (GI) and subsequently the capability to adhere to and invade Caco-2 cells, was tested at each sampling point. After 2-min of washing procedures, reductions of S. Enteritidis on strawberries were ≥1.2 log, with no significant differences among treatments. However, the use of WUV-C + PAA treatment achieved the highest reductions in washing water, in which S. Enteritidis was not detected (<DL). At the end of 5-day storage period, reductions of the WUV-C + PAA treated-samples were lower in comparison with PAA-treated samples (P < 0.05). The effect of the treatments used did not interfere with the survival of S. Enteritidis along the GI tract. After disinfection and subsequent GI simulation, all remaining populations demonstrated an elevated ability to adhere in Caco-2 cells (67.5–81.1%) compared with those obtained on untreated strawberries (61.4%). Concerning the ability of invasion, no significant differences could be observed. Remarkably, after 5 days at 4 °C, the adherence of S. Entertidis significantly decreased in the samples with the combined treatment meanwhile the invasion ability was not detected for any treatment. The results of the present study are essential for the quantitative microbial risk estimations.info:eu-repo/semantics/publishedVersio