ESTUDO DA INFLUÃNCIA DE PSICROTRÃFICOS AERÃBIOS E DE ...

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Extended Abstract STUDY THE INFLUENCE OF AEROBICS PSYCHROTROPHS AND ENTEROBACTERIACEAE IN LISTERIA MONOCYTONEGES 1/2a and 4b SURVIVAL ON MINIMAL PROCESSED SALADS All vegetables in their natural state are susceptible to spoilage by microorganisms at a rate that depends on various intrinsic and extrinsic factors. Consumers are increasingly demanding for convenient ready-to-eat vegetables and with fresh like quality, containing only natural ingredients. Plant tissues themselves, even having been contaminated by undesirable microorganisms, represent a well-defined ecosystem, and therefore different preservation methods should be use to guarantee their stability and safety as a food. Additionally, decontamination procedures to reduce the initial microbial load of raw material and methods to avoid postprocess contamination change the original micro flora of the ecosystem, affecting the kind of microbial consortium that can be established afterwards. Ready-to-eat vegetables retain much of their native indigenous flora after minimal processing and some pathogens may form part of this micro flora, posing a potential safety problem. Listeria monocytogenes is a micro organism widely distributed on plant vegetation. Plants and plant parts used as vegetable salads play a key role in disseminating pathogens from natural habits into the human food supply chain. L. monocytogenes is a psychrotropic organism, capable of growing at refrigeration temperatures, and it is also a facultative anaerobe, therefore, capable of survival/growth under low O 2 concentrations present in modified-atmosphere packaged vegetables. By screening out these characteristics, we are able to study the micro organism growth, obtaining important understanding of salads conditions and sanity state, necessary to produce data for predictive models elaboration. This thesis main objective was to i) study the growth development of spiked L. monocytogenes in minimally processed salads, through the simulation of their storage conditions in consumer’s fridges and to ii) understand how the native micro flora present has an influence in its growth. Thus, to control both presence and concentration of some microorganisms in these salads, simple microbiological analysis were performed for psychrotrophs, Enterobacteriaceae, Escherichia coli, Aeromonas hydrophila, iv
Clostridium perfringens, Bacillus cereus e L. monocytogenes. To evaluate the presence in this product of Listeria monocytogenes, Salmonella spp. e E. Coli O157 H7, the Enzymelinked Fluorescent Assay method (ELFA) was used. Sixty seven samples of salad, consisting mostly in leafy vegetables, belonging to 3 different brands and 7 different iv
Page 1 and 2: ESTUDO DA INFLUÊNCIA DE PSICROTRÓ
Page 3 and 4: Agradecimentos À minha orientador
Page 5: Abstract STUDY THE INFLUENCE OF AER
Page 9 and 10: Índice Agradecimentos ............
Page 11 and 12: 3.5.1 - Preparação e determinaç
Page 13 and 14: Índice de Quadros Quadro 1 - Ingre
Page 15 and 16: 1. Introdução As doenças transmi
Page 17 and 18: Segundo dados presentes no relatór
Page 19 and 20: 2. Revisão Bibliográfica 2.1 - Sa
Page 21 and 22: talos com aplicação de gelo funde
Page 23 and 24: A actividade enzimática constitui
Page 25 and 26: 2002). É conveniente conhecer actu
Page 27 and 28: 2.3.1 - Listeria monocytogenes em s
Page 29 and 30: 2.4 - Listeriose, surtos alimentare
Page 31 and 32: Actualmente existe um conjunto de r
Page 33 and 34: 3 - Materiais e Métodos 3.1 - Esti
Page 35 and 36: 3.3.3 - Meios utilizados na contage
Page 37 and 38: de Enterobacteriaceae. Este meio de
Page 39 and 40: que as células de Salmonella spp.
Page 41 and 42: Para isolamento usaram-se os meios
Page 43 and 44: O API 20E é também um sistema de
Page 45 and 46: Figura 8 - Operação de toma de am
Page 47 and 48: Quadro 4 - Ensaios realizados para
Page 49 and 50: microrganismos, isto é, de forma a
Page 51 and 52: Quadro 5 - Testes bioquímicos de d
Page 53 and 54: min). Após arrefecimento do tubo (
Page 55 and 56: As estirpes isoladas foram posterio
Page 57 and 58:
3.5.2 - Objectivo da contaminação
Page 59 and 60:
validade no dia da realização das
Page 61 and 62:
Quadro 7 - Contagem de microrganism
Page 63 and 64:
De forma a relacionar a contagem de
Page 65 and 66:
Nº de amostras 4.1.4 - Contagem de
Page 67 and 68:
4.2 - Resultados da contaminação
Page 69 and 70:
log (cresc. estirpe 4b) log (cresc.
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diferenças sensoriais entre cada p
Page 73 and 74:
diferenciada, tendo em conta o nív
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Da totalidade de B. cereus encontra
Page 77 and 78:
destas correlações estudadas pode
Page 79 and 80:
7 - Referências bibliográficas A
Page 81 and 82:
LECLERCQ, A. (2004). Atypical colon
Page 83 and 84:
PINE, L.; KATHARIOU, S.; QUINN, F.;
Page 85 and 86:
8 - Cybergrafia citada e consultada
Page 87 and 88:
Água destilada 1 L (pH 7,4) Proced
Page 89 and 90:
5. Misturar os seguintes constituin
Page 91 and 92:
Anexo 8 - Composição e modo de pr
Page 93 and 94:
Cloreto de magnésio 6 H 2 O 28,600
Page 95 and 96:
Anexo 16 - Composição e modo de p
Page 97 and 98:
Esculina 1,000 g Cloreto de lítio
Page 99 and 100:
8. Após reconstituição e arrefec
Page 101 and 102:
Procedimento 1. Antes da utilizaç
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Page 105 and 106:
Page 107 and 108:
Anexo 33 - Resultados das análises
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08-1057 F Cesar 01-06-08 27-05-08 2
Page 111 and 112:
08-566 < 1,0E+02 Negativo Negativo
Page 113:
Código amostra Cont.inicial (4b) C
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