Browsing by Author "Pereira, Rui"
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- Determination of soluble and insoluble dietary fiber content of marine macroalgae and microalgaePublication . Nova, Paulo; Martins, Ana Pimenta; Silva, Joana Gabriela; Pereira, Rui; Abreu, Helena; Silva, Ana Machado; Freitas, Ana; Gomes, Ana
- Evaluation of nitrite reduction on the microbial safety of cooked smoked pork chouriçoPublication . Nunes, Maria; Cruz, Inês; Noronha, Lúcia; Komora, Norton; Pereira, Rui; Barbosa, Joana; Carvalho, Fátima; Teixeira, PaulaAim: Nitrite is a preservative used worldwide, particularly in the meat industry, to guarantee certain organoleptic and microbiological properties of delicatessen meat products, acting as a hurdle to pathogenic bacteria and protecting against bacterial spoilage. Cooked smoked pork chouriço contains nitrite in its formulation, which raises some concerns regarding the consumer’s health, and therefore the European legislation on the use of nitrites has been modified, where the maximum limit of 150 mg/kg of meat has been reduced to 80 mg/ kg of meat in the EU. The present study focuses on the assessment of the impact of nitrite reduction on the microbiological safety and organoleptic properties of pork chouriço. Method: The determination of total viable counts, lactic acid bacteria, Enterobacteriaceae, Escherichia coli and pathogenic bacteria (Listeria monocytogenes, Salmonella and spores of sulfito-reducing Clostridium) was performed according to ISO standards in pork chouriço produced with different nitrite concentrations. Organoleptic characteristics, such as colour, aw, pH and texture were evaluated at times 0 days, 30 days and 60 days of storage under vacuum at room temperature. Results: Although the nitrite concentration has been reduced to almost half of the usual concentration, the microbiological results show that that the product remains stable in 60 days of vacuum storage at room temperature and complies with the legal limits, below 1.0E+05 CFU/g for total viable counts and lactic acid bacteria. Regarding organoleptic properties, due to the heterogeneity of the product, the results show some high standard deviation, especially in colour and texture, but both aw and pH are in lign with the standard values obtained in the products. Conclusion: In conclusion, although further tests are needed to establish safety, no significant differences were observed in microbial growth during the product’s shelf-life, or in its organoleptic properties. Therefore, there is no evidence of safety problems associated with the consumption of smoked cooked pork chouriço with a decrease of more than 45% in the nitrite concentration. However, caution should be taken until further research confirms its safety.
- Impact of nitrite reduction on the microbiological safety of cooked pork hamPublication . Nunes, Maria J. M.; Noronha, Lúcia; Cruz, Inês; Komora, Norton; Pereira, Rui; Barbosa, Joana; Carvalho, Fátima; Teixeira, Paula
- Neutrophil and monocyte activation in chronic kidney disease patients under hemodialysis and its relationship with resistance to recombinant human erythropoietin and to the hemodialysis procedurePublication . Pereira, Rui; Costa, Elísio; Gonçalves, Marta; Miranda, Vasco; Faria, Maria do Sameiro; Quintanilha, Alexandre; Belo, Luís; Lima, Margarida; Santos-Silva, AliceThe aim of the present work was to further clarify leukocyte activation due to hemodialysis (HD) procedures and to investigate its relationship with recombinant human erythropoietin resistance. Therefore, we studied the expression of CXCR1 and CD11b on neutrophils, as well as the monocyte expression of CD11b, HLA-DR, and CD14. We studied 34 chronic kidney disease (CKD) patients under HD and recombinant human erythropoietin treatment (26 responders and 8 nonresponders to recombinant human erythropoietin therapy). All CKD patients' blood samples were collected before and immediately after the HD procedure. Eighteen healthy individuals (blood donors) were also studied as a control group. Hematological data, neutrophil (CD11b and CXCR1), and monocyte (CD11b, HLA-DR, and CD14) cell surface markers were measured in all patients (before and after the HD procedure) and controls. When compared with the controls, CKD patients presented a significant decrease in CXCR1 neutrophil expression, and in CD14 monocyte expression, accompanied by a significant increase in HLA-DR monocyte expression. When comparing the 2 groups of patients, we found that nonresponders showed an additional decrease in CXCR1 neutrophil expression. After the HD procedure, a statistically significant increase in CD14 and CD11b monocyte surface markers and a decrease in CXCR1 neutrophil expression and in HLA-DR monocyte expression was found. These data further strengthen our previous studies, showing that neutrophils and monocytes are activated in CKD patients, particularly in nonresponder patients. Moreover, this activation is due, at least in part, to the HD procedure, although we should not exclude that it can also be due to the enhanced inflammatory process observed in nonresponder patients.