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| Author(s): |
Ana Lucia Pontes Penteado
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos |
| Defense date: | 2003-11-03 |
| Examining board members: |
Mauro Faber de Freitas Leitão;
Hilary Castle de Menezes;
Arnaldo Yoshiteru Kuaye;
Bernadette D. G. M Franco
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| Advisor: | Mauro Faber de Freitas Leitão |
| Abstract | |
In the first part of the project, the incidence of Salmonella spp. and Listeria spp. on the surface of low acid fruits (melon, watermelon and papaya) was studied. From the total of 120 fruit samples 42 were simultaneously analyzed by the TECRA Visual Immunoassay (TECRA VIA) and the modified BAM for Salmonella and by the Health Protection Branch, Canada, and TECRA VIA for Listeria; the remaining 78 fruit samples were analyzed only by the cultural procedures. Salmonella spp. was absent in ali the samples analyzed using both methods as was L. monocytogenes. However, L. innocua and L. grayii were detected in watermelon samples, L. ivanovii in papaya samples and L. welshimeri in melon .samples when using the Health Protection Branch method. It was also observed that the samples collected in street markets showed a higher incidence of Usteria spp. when compared to those collected in wholesale markets. In the second part of the project, the ability of Salmonella Enteritidis and Listeria monocytogenes to grow in fruit pulp (melon, watermelon and papaya) incubated under different conditions of time and temperature, was studied. The generation times (g) for S. Enteritidis in melon at 10°C, 20 °C and 30°C were 7.31, 1.69 and 0.69 h respectively; for watermelon 7.47, 1.60 and 0.51 h respedively and for papaya 16.61, 1.74 and 0.66 h respectively. For L. monocytogenes the generation times for melon, watermelon and papaya were 7.12, 13.03 and 15.05 h at 10°C respectívely, 1.74,2.17 and 6.42 h at 20°C and 0.84,1.00 and 1.16 h at 30°C. The results showed that both S. Enteritidis and L. monocytogens could grow in low acid fruits and that a temperature of 10°C, although capable of reducing the rate of growth of these microorganisms, could not guarantee their inhibition. In the third part of this project the possibility of the infiltration of S. Enteritidis into mangoes (after being submitted to hot water treatment to eliminate fly larvae), was studied. This project was carried out at the Food and Drug Administration-FDA in the USA Using a dye (Brilliant blue FCF/Sigma), the results showed the ability of the microorganism to infiltrate the mangoes, which was detected in 67% of the fruits submitted to the treatment. In the experiments performed directly with S. Enteritidis fluorescent serotype S 132, the infiltration levels were higher (87%) both for green and early-ripened mangoes. It was also observed that bacterial infiltration was more evident in the stem portion when compared to the bottom and middle portions (AU) | |