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| Author(s): |
Fernanda Barbosa dos Reis
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2010-02-26 |
| Examining board members: |
Elaine Cristina Pereira de Martinis;
Juliana Pfrimer Falcão;
Judite das Graças Lapa Guimarães
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| Advisor: | Elaine Cristina Pereira de Martinis |
| Abstract | |
Minimally processed ready-to-eat foods may be contaminated with Listeria monocytogenes, which causes severe infection mainly in immunocompromised persons and in pregnant women. The application of combined treatments in foods is a promising alternative for the effective inhibition of L. monocytogenes and, in this work, the inhibitory effect of alecrim pimenta (Lippia sidoides Cham.) and lactic acid bacteria was studied. The Minimum Inhibitory Concentration (MIC) of liquid and dried preparations of alecrim pimenta was determined in different temperatures, combined or not with strains of Carnobacterium maltaromaticum (C2, A9b- and A9b+). The combined use of cultures of C. maltaromaticum bacteriocin-producing (C2 and A9b+).and non bacteriocin-producing (A9b-) with or without EAP (hydroalcoholic extract of alecrim pimenta) towards L. monocytogenes was also determined in model fish systems (fish model broth, surubim fish broth and surubim homogenate, at 5°C for 35 days. The results of MICs of EAP against L. monocytogenes were 1.34 µl/ml and 0.89 µl/ml, respectively at 37ºC and 5°C, indicating synergistic effect between EAP and low temperature. Among the preparations of alecrim pimenta tested, EAP showed the highest antilisterial activity, but it also inhibited carnobacteria. No synergistic effect of EAP combined with bacteriocin of C. maltaromaticum C2 was observed. In co-inoculation studies in model fish systems, monocultures of L. monocytogenes and C. maltaromaticum (C2, A9b+ and A9b-) reached final populations of 106-108 CFU/ml. In fish model broth, EAP alone and combined with cultures of C. maltaromaticum (C2- or A9b or A9b+) presented inhibitory effect against L. monocytogenes. However, C. maltaromaticum (C2 or A9b- or A9b+) without EAP caused weak inhibition of L. monocytogenes. In surubim fish broth, C. maltaromaticum C2 was the most efficient culture for inhibiting L. monocytogenes and bacteriocin was produced. In surubim homogenate with high inoculation level, EAP alone and combined with cultures of C. maltaromaticum (A9b- or A9b+) presented stronger inhibitory effect towards L. monocytogenes, while C. maltaromaticum C2 with EAP caused only initial inhibition of L. monocytogenes, that reached final population of ca. 106 CFU/ml. C. maltaromaticum C2 or A9b- inoculated in surubim homogenate with high inoculation level without EAP reduced 3 log of CFU/ml of L. monocytogenes, but in the same condition it was observed only the reduction of 1 log of CFU/ml for C. maltaromaticum A9b+. In surubim homogenate with low initial populations of L. monocytogenes (<10 CFU/ml) it was observed that EAP alone and combined with co-cultures of C. maltaromaticum (C2 or A9b- or A9b+) presented antilisterial effect. However, C. maltaromaticum (C2 or A9b- or A9b+) without EAP did not inhibit L. monocytogenes. It was observed that the use of EAP and cultures of carnobacteria have potential to inhibit L. monocytogenes in fish and that the applications should be carefully studied, considering the influence of food matrix. (AU) | |
| FAPESP's process: | 07/05995-0 - Biopreservation of fish (surubim Pseudoplatystoma sp) with use of the bacteriocinogenic lactic acid bacteria (Carnobacterium piscicola C2) and plant extracts of rosemary pepper (Lippia sidoides Cham.) |
| Grantee: | Fernanda Barbosa dos Reis Teixeira |
| Support Opportunities: | Scholarships in Brazil - Master |