UV-C doses to reduce pathogen and spoilage bacterial growth in vitro and in baby spinachReport as inadecuate




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The aim of this work was to investigate the use of different doses of UV-C 0, 2.4, 7.2, 12 and 24 kJm−2radiation treatments to inhibit microbial growth of Listeria monocytogenes and Salmonella enterica. Thespoilage bacteria Pseudomonas marginalis gram negative was also tested. These bacteria were studiedunder in vitro conditions and in baby spinach leaves in vivo conditions for 13 and 14 dat 5 ◦C, respectively.All radiation doses were effective in reducing bacterial growth, although contrary to expectations, highdoses did not show the highest microbial inhibition in in vitro experiments. UV-C doses 2.4–24 kJm−2were also used on baby spinach Spinacia oleracea L. leaf surfaces, stored under humidified air usingperforated plastic film. A clear inhibitory UV-C effect was observed on L. monocytogenes for 14 d at 5 ◦C.Meanwhile, UV-C radiation reduced S. enterica loads until the first 4 d of storage, after which a significantincrease was found on radiated leaves compared to the control. P. marginalis counts were slightly reducedin UV-C treated leaves. In addition, significant decreases in psychrotrophic counts and Enterobacteriaceaewere found during the first 4 d of storage. Respiration rates of baby spinach leaves were higher in radiatedthan in non-radiated leaves. Moreover, no obvious damage on the epidermal surface and to cell shapewas detected in radiated and non-radiated leaves by scanning electronic microscopy SEM. In summary,the use of double-sided UV-C radiation, at low doses, was effective in reducing initial microbial counts ofthe tested bacteria types and psychrotrophic and Enterobacteria counts, and in keeping L. monocytogenesat low levels during the storage period, without affecting the sensory quality of fresh-cut baby spinachleaves.



Author: Aguayo, Encarna; - Martínez Hernández, Ginés B.; - Artés, Francisco; - Escalona Contreras, Víctor; -

Source: http://repositorio.uchile.cl/



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