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Antimicrobial packaging system for optimization of electron beam irradiation of fresh produceHan, Jaejoon 30 October 2006 (has links)
This study evaluated the potential use of an antimicrobial packaging system in
combination with electron beam irradiation to enhance quality of fresh produce.
Irradiated romaine lettuce up to 3.2 kGy showed negligible (p > 0.05) changes in color,
but texture and sensory attributes were less acceptable with increased dose.
We established the antimicrobial effectiveness of various active compounds
incorporated into the low-density polyethylene (LDPE)/polyamide films to increase
radiation sensitivity of surrogate bacteria (Listeria innocua and Escherichia coli). All
films showed inhibition zones in an agar diffusion test. In the liquid culture test, the
active compounds reduced the specific growth rate and decreased final cell concentration
of strains. Films incorporated with active compounds increased the radiation sensitivity
of the tested strains, demonstrating their potential to reduce the dose required to control
microbial contamination using electron beam technology. The active compounds
maintained their antimicrobial activity by exposure to ionizing radiation up to 3 kGy. Antimicrobial activity of LDPE/polyamide films incorporated with transcinnamaldehyde
was tested with fresh-cut romaine lettuce. Total aerobic plate counts
(APC) and yeast and mold counts (YMC) were determined as a function of dose (0, 0.5,
and 1.0 kGy) for 14 days of storage at 4ðC. Irradiation exposure significantly lowered
APCs of lettuce samples by 1-log CFU/g compared to the non-irradiated controls;
however, it only slightly reduced YMCs. The effectiveness of using irradiation with
antimicrobial films was enhanced with increased radiation dose and transcinnamaldehyde
concentration.
Electron beam irradiation up to 20 kGy did not affect the tensile strength and
toughness of the polymeric films. The filmâÂÂs flexibility and barrier properties were
significantly improved by exposure to 20 kGy. The addition of an active compound did
not affect the tensile strength and barrier properties of the films, but decreased the
percent elongation-at-break and toughness, making them slightly more brittle.
Ionizing radiation affected the release kinetics of the antimicrobial agent from the
packaging material into a model food system. Irradiated films exhibited slower release
rates than non-irradiated film by 69%. In addition, release rate was lower at 4úC by
62.6% than at 21-35úC. The pH of the simulant solution affected release rate with pH 4
yielding higher rates than pH 7 and 10.
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DYNAMICS OF WASH WATER PARAMETERS IN THE SANITIZATION OF FRESHLY-CUT PRODUCEAlradaan, Ali 18 May 2018 (has links)
No description available.
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Attachment, Internalization, and Dissemination of Human Norovirus and Animal Caliciviruses in Fresh ProduceDiCaprio, Erin L. 27 June 2012 (has links)
No description available.
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Effets des rayonnements UV-C sur la réponse de la laitue romaine Lactuca sativa var Claudius aux contraintes biotoques et abiotiques / Effects of UV-C radiations on the response of romaine lettuce to biotic and abiotic stressesOuhibi, Chayma 20 December 2014 (has links)
Appliqués à forte dose, les rayonnements UV-C sont délétères, alors que administrés à faibles doses, ces memes rayonnements stimulent des réponses bénéfiques. Ce phénomène est connu sous le nom d’hormesis et la dose bénéfique est qualifiée d’hormique. L’application des faibles doses d’UV-C sur les fruits et les légumes en post-récolte a permis donc d’augmenter leur résistance vis à vis des pathogènes (Charles et al, 2008), d’améliorer leur qualité nutritionnelle (Mercier et al, 2001) et d’améliorer leur rendement et leur croissance (Siddiqui et al, 2011). Ces travaux ont été réalisés sur des espèces différentes. Dans le cadre de ma thèse, nous avons traité une seule espèce de laitues romaines var Claudius après récolte avec une dose non délétère d’UV-C (0.85kJ.m-2) puis nous avons évalué son effet sur leur aspect de résistance aux champignons Botrytis cinerea (BC87) et Sclerotinia minor (SM), sur leurs valeurs nutritionnelles au cours du stockage et sur leurs réponses à la contrainte saline du milieu. L’analyse de tous les résultats obtenus,a mis en évidence que la dose d’UV-C choisie diminue la sensibilité de la laitue romaine à ces deux agents pathogènes (Ouhibi et al. 2014a), améliore sa valeur nutritionnelle en augmentant la concentration des composées phénoliques et de l’acide ascorbique et acquière aux plantes provenant de grains prétraitées aux UV-C un meilleur potentiel d'adaptation à la contrainte saline (Ouhibi et al, 2014 b). Le traitement des plantes avec une dose d’UV-C non délétère permet d’agir de façon bénéfique et simultanément sur différents processus physiologiques. / Applied in high doses, UV-C radiations are harmful, while administered at low doses, these same radiations stimulate beneficial answers. This phenomenon is known as hormesis and the beneficial dose is qualified hormic. The application of low doses of UV-C on fruits and vegetables in post harvest enhances resistance against pathogens (Charles et al, 2008), improve their nutritional quality (Mercier et al, 2001) and their performance to grow (Siddiqui et al, 2011). This works were carried out on different species. In my thesis, we treated a single species of romaine lettuce var claudius after harvest with a non-harmful dose of UV-C (0.85kJ.m-2) and we evaluated its effect on resistance to Botrytis cinerea (BC87) and Sclerotinia minor (SM), in their nutritional value during storage and their responses to salt stress. The analysis of all the results obtained showed that the UV-C dose decreases the sensitivity of romaine lettuce to these two pathogens (Ouhibi et al. 2014a), improve nutritional value by increasing the content in phenolic compound, in ascorbic acid and acquire to plants from seeds pre-treated with UV-C greater potential for adaptation to salt stress (Ouhibi et al, 2014 b).
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