Efeito combinado da utilização de bactérias do ácido lático e vinho no controlo da microflora patogénica em enchidos secos e crus
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2014
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Ao longo do tempo os enchidos tornaram-se uma classe independente de alimentos com diferentes especialidades regionais, apreciadas pela sua elevada diversidade de atributos sensoriais. No caso da carne, as bactérias do ácido lático constituem uma parte da microflora inicial que se desenvolve facilmente depois de a carne ser processada. A sua utilização como obstáculo ao crescimento microbiano patogénico e deteriorativo é sem dúvida promissora devido principalmente ao fato de secretarem substâncias antimicrobianas como as bacteriocinas.
O presente trabalho teve como objetivos: testar a atividade antagonista de estirpes Lactobacillus sakei previamente isoladas de enchidos tradicionais contra alguns microrganismos patogénicos com maior importância ao nível alimentar, particularmente Listeria monocytogenes. Pela constatação da perda da atividade antagonista anteriormente verificada pelas mesmas estirpes, procedeu-se à sua estimulação para a produção de BLIS (Bacteriocin Like Inhibitory Substance) utilizando duas estratégias: 1) limitação nutricional do meio; 2) competição, através de co-cultura com bactérias pertencentes à microflora natural de enchidos. Após recuperação do fenótipo produtor de BLIS, testou-se o seu efeito inibitório combinado com o efeito inibitório do vinho sobre L. monocytogenes e outras bactérias. Por fim testou-se a eficácia deste efeito combinado no controlo de Listeria no chouriço comparando a utilização de uma cultura de arranque de Lb. sakei fenótipo produtor de BLIS com outra cultura de arranque com fenótipo não produtor. Num primeiro despiste da atividade antagonista contra diferentes bactérias patogénicas, verificou-se uma perda da atividade antagonista outrora (anteriormente) observada. A estratégia de estimulação surtiu efeito uma vez que, a atividade antagonista aumentou substancialmente após o período de indução de produção de BLIS. O comportamento de L. monocytogenes tratada com sobrenadante de Lb. sakei produtora de BLIS obteve um comportamento diferentes das restantes estirpes testadas na presença de vinho, pois um menor crescimento se registou com concentrações nulas de vinho prevendo que esta estirpe tenha um efeito inibitório inversamente proporcional à concentração de vinho.
Over time sausages become an independent class of foods with different regional specialties, enjoyed by their diversity of organoleptic properties. In the meat, the lactic acid bacteria is a part of the initial microflora, which is easily developed after the meat has been processed. Its use as a hurdle to pathogens growth and deteriorating is certainly promising, mainly from fact they segregate antimicrobial substances such as bacteriocins. This work aims: to test the antimicrobial activity of the Lb. sakei strains, isolated from traditional sausages against pathogenic microorganisms with greater importance to food, specifically L. monocytogenes. By finding the loss of antagonist activity previously verified by the same strains, it was performed a strains stimulation for BLIS production using two strategies: 1) nutritional limitation in the media. 2) competition by co-culture of LAB with Staphylococcus warneri and S. saprophyticus. After the recovery of the phenotype BLIS producer, we tested its inhibitor effect combined with the wine on L. monocytogenes and other sensitive bacteria. The efficiency of the combined effect of LAB and wine on the Listeria monocytogenes behaviour in chouriço. A starter culture with a Lb. sakei BLIS producer was compared to other not producer. Initially screened for the antagonist activity against different pathogenic bacteria, it was observed a loss of the antagonist activity previously present. The stimulation strategy was effective, once the antagonist activity had a significantly increase, after the period of induction for BLIS production L. monocytogene was inhibited both by the wine and by the supernatant of the BLIS producer Lb. sakei The use of Lb. sakei with the phenotype producer of BLIS in chouriço manufacture was much more effective than a non-producer strain. Lowers counts of L. monocytogenes were obtained when strains producers of BLIS were used simultaneously with wine.
Over time sausages become an independent class of foods with different regional specialties, enjoyed by their diversity of organoleptic properties. In the meat, the lactic acid bacteria is a part of the initial microflora, which is easily developed after the meat has been processed. Its use as a hurdle to pathogens growth and deteriorating is certainly promising, mainly from fact they segregate antimicrobial substances such as bacteriocins. This work aims: to test the antimicrobial activity of the Lb. sakei strains, isolated from traditional sausages against pathogenic microorganisms with greater importance to food, specifically L. monocytogenes. By finding the loss of antagonist activity previously verified by the same strains, it was performed a strains stimulation for BLIS production using two strategies: 1) nutritional limitation in the media. 2) competition by co-culture of LAB with Staphylococcus warneri and S. saprophyticus. After the recovery of the phenotype BLIS producer, we tested its inhibitor effect combined with the wine on L. monocytogenes and other sensitive bacteria. The efficiency of the combined effect of LAB and wine on the Listeria monocytogenes behaviour in chouriço. A starter culture with a Lb. sakei BLIS producer was compared to other not producer. Initially screened for the antagonist activity against different pathogenic bacteria, it was observed a loss of the antagonist activity previously present. The stimulation strategy was effective, once the antagonist activity had a significantly increase, after the period of induction for BLIS production L. monocytogene was inhibited both by the wine and by the supernatant of the BLIS producer Lb. sakei The use of Lb. sakei with the phenotype producer of BLIS in chouriço manufacture was much more effective than a non-producer strain. Lowers counts of L. monocytogenes were obtained when strains producers of BLIS were used simultaneously with wine.
Descrição
Dissertação de Mestrado em Biotecnologia e Qualidade Alimentar
Palavras-chave
Lactobacillus sakei , Listeria monocytogenes , Salmonella , Vinho , Enchidos