scholarly journals Inactivation of Listeria monocytogenes on post-harvest carrot and tomato by gamma radiation, sanitizer, biocontrol treatments and their combinations

LWT ◽  
2020 ◽  
Vol 118 ◽  
pp. 108805 ◽  
Author(s):  
A. Berrios-Rodriguez ◽  
O.M. Olanya ◽  
D.O. Ukuku ◽  
B.A. Niemira ◽  
L.E. Orellana ◽  
...  
2014 ◽  
Vol 77 (10) ◽  
pp. 1768-1772 ◽  
Author(s):  
ANA CAROLINA B. REZENDE ◽  
MARIA CRYSTINA IGARASHI ◽  
MARIA TERESA DESTRO ◽  
BERNADETTE D. G. M. FRANCO ◽  
MARIZA LANDGRAF

This study evaluated the effects of irradiation on the reduction of Shiga toxin–producing Escherichia coli (STEC), Salmonella strains, and Listeria monocytogenes, as well as on the sensory characteristics of minimally processed spinach. Spinach samples were inoculated with a cocktail of three strains each of STEC, Salmonella strains, and L. monocytogenes, separately, and were exposed to gamma radiation doses of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 kGy. Samples that were exposed to 0.0, 1.0, and 1.5 kGy and kept under refrigeration (4°C) for 12 days were submitted to sensory analysis. D10-values ranged from 0.19 to 0.20 kGy for Salmonella and from 0.20 to 0.21 for L. monocytogenes; for STEC, the value was 0.17 kGy. Spinach showed good acceptability, even after exposure to 1.5 kGy. Because gamma radiation reduced the selected pathogens without causing significant changes in the quality of spinach leaves, it may be a useful method to improve safety in the fresh produce industry.


Author(s):  
MARIA APARECIDA COSTA ◽  
VALDEMAR LUIZ TORNISIELO ◽  
JULIO MARCOS MELGES WALDER

O objetivo deste trabalho foi avaliar os níveis residuais de Prochloraz aplicado em mangas, na pré e pós-colheita após o tratamento com radiação. Os frutos foram submetidos à radiação gama na dose de 1,0 kGy visando verificar se a mesma induziu a degradação do fungicida. As mangas tratadas na pós-colheita foram armazenadas por 21 dias a 12 °C. Os resíduos de Prochloraz não apresentaram decréscimo durante o período de carência (21 dias) estabelecido pela Legislação Brasileira de Agrotóxicos. O armazenamento refrigerado (12 °C) e a irradiação gama também não contribuíram para a degradação do fungicida. O Prochloraz ficou retido principalmente na casca (média = 1,64 µg/g), que funcionou como barreira à contaminação da polpa (média = 0,06 µg/g). O produto de degradação, formado nas cascas das mangas tratadas na pós-colheita, foi identificado como sendo o BTS 44596. Os metabólitos, encontrados em níveis baixos, confirmaram a ocorrência de baixa degradação do fungicida em mangas. 14C-PROCHLORAZ RESIDUES IN IRRADIATED MANGOES Abstract The aim of this work was to evaluate the Prochloraz residual levels applied in mangoes, in pre and post-harvest after radiation treatment. The fruits were submitted to gamma radiation with of 1,0 kGy dose, aiming to verify if it induces the fungicide degradation. Treated post-harvest mangoes were stored, at 12 0C during 21 days. Prochloraz residues did not present reduction after safe period (21 days), established by the Brazilian legislation on agrochemicals. The refrigerated storage (12 0C) and the gamma radiation also did not contribute to the degradation of the fungicide. Prochloraz was mainly retained in the peels (mean = 1,64 µg/g) which served as barrier to the pulp (mean = 0,06 µg/g) contamination. The degradation product, formed in peels of post-harvest treated mangoes was the metabolite BTS 44596. The metabolites found in very low levels, confirm that low fungicide degradation occurs in mangoes.


2006 ◽  
Vol 69 (12) ◽  
pp. 2961-2969 ◽  
Author(s):  
STÉPHANE CAILLET ◽  
MONIQUE LACROIX

The effects of gamma radiation and of oregano essential oil alone or in combination with radiation on murein composition of Listeria monocytogenes and on the intracellular and extracellular concentration of ATP were evaluated. The bacterial strain was treated with two radiation doses, 1.2 kGy to induce cell damage and 3.5 kGy to cause cell death. Oregano essential oil was used at 0.020 and 0.025% (wt/vol), which is the MIC. All treatments had a significant effect (P ≤ 0.05) on the murein composition, although some muropeptides did not seem to be affected by the treatment. Each treatment influenced differently the relative percentage and number of muropeptides. There was a significant correlation (P ≤ 0.05) between the reduction of intracellular ATP and increase in extracellular ATP, following treatment of the cells with oregano oil. The reduction of intra-cellular ATP was even more important when essential oil was combined with irradiation, but irradiation of L. monocytogenes alone induced a significant decrease (P ≤ 0.05) of the internal ATP without affecting the external ATP. Transmission electron microscopic observation revealed that oregano oil and irradiation have an effect on cell wall structure.


1997 ◽  
Vol 60 (3) ◽  
pp. 262-266 ◽  
Author(s):  
L. S. ANDREWS ◽  
R. M. GRODNER

The purpose of this study was to determine if split dose application of gamma radiation would alter the radiosensitivity of L. monocytogenes. Concentrations of 106 and 109 CFU L. monocytogenes per ml were suspended in tryptic soy broth and exposed to 0 to 5 kGy gamma radiation at 20, 4, and −80°C with equal split doses at 0- to 2-h time intervals (times between fractions, TBFs). Regression analyses of survival plots were used to calculate irradiation D values. Irradiation D values for split doses with 1- and 2-h TBFs were significantly lower than the control value and the values for 0.25- and 0.50-h TBFs (P < .05) at 20°C but this was not true at 4 or − 80°C With 1- and 2-h TBFs at 20°C the bacterium was near its generation time of 1.2 h, possibly accounting for the increased sensitivity. Results of this study indicated that split dose application increased the sensitivity of Listeria under certain conditions and that further investigation into this method is warranted.


1965 ◽  
Vol 24 (1) ◽  
pp. 96 ◽  
Author(s):  
R. H. Stewart ◽  
J. F. Pribnow ◽  
M. S. Silverman

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