Browsing by Author "Casquete, Rocío"
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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 combined effect of chitosan and lactic acid bacteria in alheira (fermented meat sausage) pastePublication . Casquete, Rocío; Castro, Sonia Marilia; Teixeira, PaulaThis study aimed to assess the efficacy of chitosan, Pediococcus acidilactici HA-6111-2 (bacteriocinogenic strain with antilisterial activity) and Pediococcus pentosaceus HA-3083-3 (a nonbacteriocinogenic strain), added individually or in combination, in the control of Listeria innocua, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium during storage of Alheira paste at 4C. The behavior of pathogenic bacteria in the food matrix was significantly affected by the addition of chitosan. Chitosan at 0.3% reduced pathogenic bacteria counts in Alheira paste by 2-3 log cfu/g during the first 7 days of storage. This effect was increased when chitosan was used synergistically with lactic acid bacteria (LAB) (P < 0.05). Sensory evaluation showed that addition of chitosan to Alheira did not affect sensory attributes. To our knowledge, this is the first study demonstrating the combined effect of bacteriocinogenic or nonbacteriocinogenic LAB and chitosan against pathogenic bacteria in fermented meats.
- 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.
- Evaluation of the microbiological safety and sensory quality of a sliced cured-smoked pork product with protective cultures addition and modified atmosphere packagingPublication . Casquete, Rocío; Fonseca, Susana C.; Pinto, Ricardo; Castro, Sónia M.; Todorov, Svetoslav; Teixeira, Paula; Vaz-Velho, ManuelaThe aim of this study was to evaluate the effect of two protective lactic acid bacteria cultures combined with modified atmosphere packaging on the survival/growth of Listeria innocua 2030c (as a surrogate for Listeria monocytogenes) and on sensory attributes of ready-to-eat ‘lombo’ over storage time. Sliced ‘lombo’, a traditional cured-smoked pork loin, was inoculated with L. innocua 2030c, Lactobacillus sakei ST153 (isolated from ‘salpicão’) and BLC35 culture (with Lactobacillus curvatus, Staphylococcus xylosus and Pediococcus acidilactici; CHR Hansen) as protective cultures. Samples were packed in two modified atmosphere packaging conditions (20% CO2/80% N2 and 40% CO2/60% N2) and stored at 5 ℃ for 124 days. Both cultures led to a reduction of 1–2 log CFU/g of L. innocua 2030c after 12 h; however, at the end of storage only Lb. sakei ST153 maintained this antilisterial effect, which was more evident at 40% CO2/60% N2. The influence of cultures addition and modified atmosphere packaging conditions on the sensory characteristics of the product were not significant. Thus, Lb. sakei ST153 combined with modified atmosphere packaging is a strong candidate to be used in a biopreservation strategy maintaining the traditional sensory quality of cured-smoked pork products and increasing their safety with respect to Listeria spp.