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  • The results showed that ethanol and acetaldehyde production

    2021-04-23

    The results showed that ethanol and acetaldehyde production was not affected by the presence of CPA-7. We observed that the concentration of ethanol increased throughout the assay up to 95–179 μL L-1 regardless of the treatment. The acetaldehyde concentration reached its highest values after 6–9 days of storage. The fact that both metabolites increased during the storage time regardless of the treatment could indicate that the microorganism did not affect to the biosynthesis of these compounds, and they were produced by the Teicoplanin metabolism. The volatile profile emitted by minimally processed Conference pear stored at 5 °C was determined; esters accounted for more than 57% of the volatile fraction of Conference wedges both treated and untreated with CaCl2. Esters are known as the most abundant class of compounds observed when using headspace analysis, and they are the volatile compounds that contribute the most to the aroma of intact and fresh-cut pears (Chen et al., 2006; Bai et al., 2009). The major esters of Conference pear aroma (butyl and hexyl acetates) are predominant in other intact Pyrus communis pears including Comice (López et al., 2001), d’Anjou (Argenta et al., 2003), and Barlett (Zlatić et al., 2016), and the esters hare highly correlated with the fruity and characteristic pear aroma (Makkumrai et al., 2014). The impact of CPA-7 inoculation on the volatile profiles of fresh-cut Conference pears differed depending on the CaCl2 treatment and cold storage time. According to the evaluation of volatile emissions during cold storage, 3 esters and 2 alcohols were only detected in Conference wedges inoculated with CPA-7 and not treated with CaCl2, namely, 3-methylbutyl acetate, butyl hexanoate, butyl propanoate, 1-hexanol and 1-octanol. Previous works have shown that 3-methylbutyl acetate and 1-octanol are present in the volatile emission profiles of intact Comice pears (Makkumrai et al., 2014), butyl hexanoate is present in d’Anjou pears, and butyl propanoate and 1-hexanol are present in intact Conference pears (Rizzolo et al., 2005).
    Conclusions To conclude, CPA-7 was able to control the growth of L. monocytogenes after 9 days of storage. On the other hand, no effect was observed on the S. enterica population under the tested conditions. These results suggested that CPA-7 did not have a bactericidal effect against foodborne pathogens. CPA-7 treatment could improve the volatile profile and did not negatively affect the fruit quality. We did not observe a clear effect of postharvest CaCl2 treatment on the efficacy of CPA-7 and on the studied quality parameters of fresh-cut pear.
    Acknowledgements Authors are grateful to the Spanish Ministry of Science and Innovation (AGL-2012-38671 research project), Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya (AGAUR fellowship 2015-FI-B100156 (M. Belén Iglesias) and 2017-FI-B200164 (Lorena Zudaire)), European Regional Development Fund (FEDER), and CERCA Programme (Generalitat de Catalunya) for their financial support. We also thank Marina Anguera, Patricia Gálvez and Mariona Guardiola for their technical support.