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- Antimicrobial activity of ethanolic extract of propolis in "Alheira", a fermented meat sausagePublication . Casquete, Rocío; Castro, Sónia Marília; Jácome, Samuel; Teixeira, PaulaThe objective of this study was to evaluate the efficacy of an ethanolic extract of propolis (EEP) in the control of Listeria innocua PHLS 2030c (as a surrogate for Listeria monocytogenes) during storage of Alheira at 4°C. Total phenolic content was evaluated to determine the minimal inhibitory concentration of EEP against the growth of L. innocua by the agar dilution method. Alheiras were manufactured by incorporating EEP (0.28 mg/mL) and pathogenic bacteria and storage during 62 days at 4°C. Growth of L. innocua was determined during storage. The behaviour of L. innocua in the food matrix was significantly affected (p < 0.01) by the addition of EEP. The ethanolic extract of propolis reduced the Listeria population to below the detection limit of the technique after 8 days of storage. These results suggest that incorporation of EEP in a food susceptible to Listeria contamination may be an interesting alternative to existing chemical preservatives and can extend the shelf life of these products.
- Evaluation of the effect of high pressure on total phenolic content, antioxidant and antimicrobial activity of citrus peelsPublication . Casquete, Rocío; Castro, Sónia Marilia; Martín, Alberto; Ruiz-Moyano, Santiago; Saraiva, Jorge A.; Córdoba, María G.; Teixeira, PaulaThis study aimed to assess the effect of high pressure at 300 and 500 MPa for 3 and 10 min on the phenolic compounds, antioxidant capacity and antimicrobial activity of citrus peel extracts. Total phenolic contents (TPC) and antioxidant properties of extracts were determined as free radical-scavenging ability of DPPH and using the ABTS radical cation decolorization assay. Additionally, extracts were tested for antimicrobial activity against twenty different strains of bacteria representing both Gram-positive and Gram-negative types. Citrus peel extracts demonstrated antimicrobial activity against a wide range of bacteria. The maximum level of TPC as well as antioxidant capacity were observed at 300 MPa for 3 min. Citrus peels extracts demonstrated antimicrobial activity against a wide range of microorganisms. The antimicrobial activity of orange peel extract was the highest among the four citrus peels studied. Generally, bacteria Acinetobacter and the strain Listeria innocua were more sensitive to the peel extracts.