| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 1.58 MB | Adobe PDF |
Abstract(s)
Este estudo teve como principal objetivo avaliar o comportamento de diferentes estirpes de Listeria monocytogenes em fiambre de porco sujeito a oscilações de temperatura durante um período de sete dias. Foi ainda objetivo do trabalho comparar os resultados obtidos experimentalmente com o comportamento de L. monocytogenes previsto utilizando softwares de microbiologia preditiva. Foram realizadas duas experiências durante os mês de maio e julho, cada uma delas envolveu a realização de dois ensaios independentes. Durante a 1ª e 2ª experiências realizadas no mês de maio e julho, com exceção do 2º ensaio referente à 2ª experiência, observaram-se oscilações no crescimento de L. monocytogenes ao longo dos 7 dias de estudo. No entanto, no 2º ensaio realizado em julho o desenvolvimento de L. monocytogenes já terá sido mais uniforme e constante ao longo do tempo, chegando a atingir valores na ordem dos 6 log UFC/g nas condições de abuso mais elevada (ex.: Lm Real 16h a 25º C e Lm Real 24h a 25º C). Nos restantes ensaios, no final de 7 dias de estudo não se atingiram valores superiores a 4 log UFC/g. Em ambas as experiências realizadas, foram detetadas bactérias do ácido lático em elevado número (ex.: valores acima dos 4 log UFC/g) e uma redução dos valores de pH ao longo dos 7 dias de estudo. Quando analisados os resultados gerados pelos modelos preditivos constatou-se que de acordo com o modelo ComBase o crescimento é contínuo ao longo do tempo e proporcional a cada abuso de temperatura a que L. monocytogenes foi sujeita. Quando utilizado o modelo Food Spoilage and Safety Predictor (FSSP), observou-se um crescimento constante até aproximadamente ao 2º dia e a partir daí foi exibida uma fase estacionária. Conclui-se que o fiambre de porco sustenta o desenvolvimento de L. monocytogenes. Constatou-se que no final de cada 7 dias de estudo as temperaturas de abuso não seriam o fator mais relevante para o crescimento, mas sim o tempo de exposição. Concluiu-se também que as bactérias do ácido lático influenciam o desenvolvimento de L. monocytogenes em fiambre. De entre os modelos de microbiologia preditiva utilizados neste estudo, destaca-se o FSSP, uma vez que é o modelo cujas previsões mais se aproximam dos resultados laboratoriais.
The main objective of this study was to evaluate the behavior of different Listeria monocytogenes strains in pork ham exposed temperature fluctuations over a seven-day period. This work also aimed to compare results obtained experimentally with the behavior of L. monocytogenes predicted using predictive microbiology software. Two experiments were carried out during May and July, each of them involved two independent trials. During the 1st and 2nd experiments conducted in May and July, with the exception of the 2nd trial referring to the 2nd experiment, oscillations in the growth of L. monocytogenes were observed during the 7 days of study. However, in the 2nd trial carried out in July the development of L. monocytogenes was more uniform and constant over time, reaching values in the order of 6 log CFU/g in the conditions of higher abuse (e.g. Lm Real 16 h to 25 ºC and Lm Real 24 h to 25 ºC). In the other trials, at the end of 7 days of study, values higher than 4 log CFU/g were not reached. In both experiments, lactic acid bacteria were found in high numbers (e.g., values above 4 CFU/g log) and a reduction in pH values over the 7 days of study was observed. When analyzed the results generated by predictive models it was found that according to the ComBase model, growth is continuous over time and proportional to each temperature abuse to which L. monocytogenes was subjected. When using the Food Spoilage and Safety Predictor (FSSP) model, there was constant growth until approximately day 2 and than stationary phase was reached. It was concluded that the pork ham supports the development of L. monocytogenes. However, it was possible to verify at the end of 7 days of study that abuse temperatures were not the most relevant factor for growth, but exposure time. It was also concluded that lactic acid bacteria influence the development of L. monocytogenes. Among the predictive microbiology models used in this study, the FSSP stands out, since it is the model that most closely approaches the reality observed in the laboratory.
The main objective of this study was to evaluate the behavior of different Listeria monocytogenes strains in pork ham exposed temperature fluctuations over a seven-day period. This work also aimed to compare results obtained experimentally with the behavior of L. monocytogenes predicted using predictive microbiology software. Two experiments were carried out during May and July, each of them involved two independent trials. During the 1st and 2nd experiments conducted in May and July, with the exception of the 2nd trial referring to the 2nd experiment, oscillations in the growth of L. monocytogenes were observed during the 7 days of study. However, in the 2nd trial carried out in July the development of L. monocytogenes was more uniform and constant over time, reaching values in the order of 6 log CFU/g in the conditions of higher abuse (e.g. Lm Real 16 h to 25 ºC and Lm Real 24 h to 25 ºC). In the other trials, at the end of 7 days of study, values higher than 4 log CFU/g were not reached. In both experiments, lactic acid bacteria were found in high numbers (e.g., values above 4 CFU/g log) and a reduction in pH values over the 7 days of study was observed. When analyzed the results generated by predictive models it was found that according to the ComBase model, growth is continuous over time and proportional to each temperature abuse to which L. monocytogenes was subjected. When using the Food Spoilage and Safety Predictor (FSSP) model, there was constant growth until approximately day 2 and than stationary phase was reached. It was concluded that the pork ham supports the development of L. monocytogenes. However, it was possible to verify at the end of 7 days of study that abuse temperatures were not the most relevant factor for growth, but exposure time. It was also concluded that lactic acid bacteria influence the development of L. monocytogenes. Among the predictive microbiology models used in this study, the FSSP stands out, since it is the model that most closely approaches the reality observed in the laboratory.
Description
Keywords
Listeria monocytogenes Alimentos prontos a comer Armazenamento Flutuações de temperatura Fiambre Microbiologia preditiva Ready-to-eat (RTE) Storage Temperature fluctuations Cooked-ham Predictive microbiology