Artículo de revista
UV-C doses to reduce pathogen and spoilage bacterial growth in vitro and in baby spinach
Fecha
2010Registro en:
Postharvest Biology and Technology 56 (2010) 223–231
doi:10.1016/j.postharvbio.2010.01.008
Autor
Escalona Contreras, Víctor
Aguayo, Encarna
Martínez Hernández, Ginés B.
Artés, Francisco
Institución
Resumen
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−2)
radiation treatments to inhibit microbial growth of Listeria monocytogenes and Salmonella enterica. The
spoilage bacteria Pseudomonas marginalis (gram negative) was also tested. These bacteria were studied
under 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, high
doses did not show the highest microbial inhibition in in vitro experiments. UV-C doses (2.4–24 kJm−2)
were also used on baby spinach (Spinacia oleracea L.) leaf surfaces, stored under humidified air using
perforated 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 significant
increase was found on radiated leaves compared to the control. P. marginalis counts were slightly reduced
in UV-C treated leaves. In addition, significant decreases in psychrotrophic counts and Enterobacteriaceae
were found during the first 4 d of storage. Respiration rates of baby spinach leaves were higher in radiated
than in non-radiated leaves. Moreover, no obvious damage on the epidermal surface and to cell shape
was 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 of
the tested bacteria types and psychrotrophic and Enterobacteria counts, and in keeping L. monocytogenes
at low levels during the storage period, without affecting the sensory quality of fresh-cut baby spinach
leaves.