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- Chitosan mouthwash: toxicity and in vivo validationPublication . Costa, E. M.; Silva, S.; Costa, M. R.; Pereira, M.; Campos, D. A.; Odila, J.; Madureira, A. R.; Cardelle-Cobas, A.; Tavaria, F. K.; Rodrigues, A. S.; Pintado, M. M.A previous study showed that a chitosan mouthwash would be a valid alternative to current mouthwashesas it demonstrated, in vitro, significantly higher antibiofilm activity than two commercial mouthwashes.As such, the aim of this work was to verify the safety of the developed product and to validate, in vivo, thebiological activity ascertained in vitro. Chitosan mouthwash safety was evaluated through Ames, MTT andV79 chromosomal aberration assay while antimicrobial activity was evaluated through in vivo assays. Theresults showed that the chitosan mouthwash was safe, presenting lower cytotoxicity than a commercialmouthwash, and that it effectively reduced viable counts of Streptococcus spp. and Enterococcus spp. by ca.5.5 log of CFU. Furthermore, in direct comparison with a commercial mouthwash the chitosan mouthwashpossessed significantly higher antimicrobial activity. The conjunction of these results proves that thechitosan mouthwash is a safe, effective, natural alternative to the existent chemical mouthwashes.
- Serpa PDO cheese: towards identification of chemical markers involved in organoleptic attributesPublication . AraĂșjo-Rodrigues, Helena; Tavaria, Freni K.; Santos, Maria Teresa P.G. Dos; Alvarenga, Nuno; Pintado, Manuela M.
- Contribution of wild strains of lactic acid bacteria to the typical aroma of artisanal cheesePublication . Tavaria, Freni; Ferreira, A. CĂ©sar Silva; Malcata, F. Xavier
- Topical application of probiotics in skin: adhesion, antimicrobial and antibiofilm in vitro assaysPublication . Lopes, E. G.; Moreira, D. A.; GullĂłn, P.; GullĂłn, B.; Cardelle-Cobas, A.; Tavaria, F. K.Aims: When skin dysbiosis occurs as a result of skin disorders, probiotics can act as modulators, restoring microbial balance. Several properties of selected probiotics were evaluated so that their topical application could be considered. Methods and Results: Adhesion, antimicrobial, quorum sensing and antibiofilm assays were carried out with several probiotic strains and tested against selected skin pathogens. All tested strains displayed significant adhesion to keratin. All lactobacilli with the exception of Lactobacillus delbrueckii, showed antimicrobial activity against skin pathogens, mainly due to organic acid production. Most of them also prevented biofilm formation, but only Propioniferax innocua was able to break down mature biofilms. Conclusions: This study demonstrates that although all tested probiotics adhered to human keratin, they showed limited ability to prevent adhesion of some potential skin pathogens. Most of the tested probiotics successfully prevented biofilm formation, suggesting that they may be successfully used in the future as a complement to conventional therapies in the treatment of a range of skin disorders. Significance and Impact of study: The topically used probiotics may be a natural, targeted treatment approach to several skin disorders and a complement to conventional therapies which present many undesirable side effects.
- A review on microbiological and technological aspects of Serpa PDO cheese: an ovine raw milk cheesePublication . AraĂșjo-Rodrigues, Helena; Tavaria, Freni K.; Santos, Maria Teresa P. G. dos; Alvarenga, Nuno; Pintado, Maria M.Serpa is a PDO cheese considered one of most popular and relevant traditional Portuguese cheeses due to its unique aroma and flavour, which are very much-appreciated characteristics. The special and recognised sensorial attributes of Serpa cheese are a result of the ingredients used, coupled with the manufacturing process, specifically raw ovine milk and extracts of Cynara cardunculus L. as coagulant, without addition of any starter culture or milk pasteurisation. Serpa quality and safety issues, linked to the high susceptibility and heterogeneity of its final sensorial attributes fosters the importance of large-scale studies focused on biochemical and microbial aspects. Despite the scientific relevance of this traditional product, Serpa studies are still very scarce and limited with the cheesemaking procedure lacking in regulation. Accordingly, the present work emphasises the current knowledge on Serpa PDO cheese, giving an overview and critical analysis of existing studies and discussing Serpa technological process.
- Antioxidant properties of sterilized yacon (Smallanthus sonchifolius) tuber flourPublication . Sousa, Sérgio; Pinto, Jorge; Rodrigues, César; Gião, Maria; Pereira, Clåudia; Tavaria, Freni; Malcata, F. Xavier; Gomes, Ana; Pacheco, M. T. Bertoldo; Pintado, ManuelaThe objective of this research work was to investigate the antioxidant properties of sterilized yacon tuber flour. The results revealed for the first time the high antioxidant activity of sterilized yacon flour. The best extract obtained by boiling 8.9% (w/v) of yacon flour in deionised water for 10 min exhibited a total antioxidant capacity of 222 ± 2 mg (ascorbic acid equivalent)/100 g DW and a total polyphenol content of 275 ± 3 mg (gallic acid equivalent)/100 g DW associated to the presence of four main phenolic compounds: chlorogenic acid, caffeic acid, coumaric acid and protocatechuic acid, as well as the amino acid tryptophan. The most abundant was chlorogenic acid, followed by caffeic acid. Biological assays revealed that the extract had indeed antioxidant protection, and no pro-oxidant activity. In conclusion, sterilized yacon tuber flour has the potential to be used in the food industry as a food ingredient to produce functional food products.
- Enzymatic activities of non-starter lactic acid bacteria isolated from a traditional Portuguese cheesePublication . Tavaria, Freni K.; Malcata, F. XavierFour strains of lactic acid bacteria, previously isolated from traditional Serra da Estrela cheese and duly identified as Lactobacillus paracasei ssp. paracasei, Leuconostoc mesenteroides ssp. dextranicum, Lactococcus lactis ssp. lactis and Enterococcus faecium, were tested for their aminotransferase, oxidase and dehydrogenase activities towards five amino acids in free form: two branched-chain (leucine and valine), one sulfur-containing (methionine) and two aromatic (phenylalanine and tryptophan) amino acids. For this purpose, both resting cells (RC) and crude cell-free extracts (CFE) were considered; their lyase and demethiolase activities (towards methionine and -keto- -methiolbutyric acid (KMBA), respectively) were also evaluated. Aminotransferase activity (AT) of RC was ca. 10-fold higher towards Met than towards Leu or Val. No AT activity was found in CFE, although these extracts displayed high dehydrogenase activity (DA) towards Phe, especially L. lactis ssp. lactis and E. faecium. In the case of L. paracasei ssp. paracasei and L. mesenteroides ssp. dextranicum, they showed high DA activity, which was ca. 10-fold higher towards Met than towards Leu or Val. E. faecium displayed high oxidase activity towards Met, and produced nine-fold more methanethiol from Met and five-fold more methanethiol from KMBA than the other three isolates under study.
- Microbiological characterization of Serra da Estrela cheese throughout its appellation d'origine protégée regionPublication . Tavaria, Freni K.; Malcata, F. X.The purpose of this study was to assess the typical microbiological quality of the most famous Portuguese traditional cheese, Serra da Estrela, and to assess its ripening time and geographical dependence. Ninety-six experimental cheeses manufactured from sixteen batches of milk on eight dairy farms scattered over the Appellation d' Origine Protégée (AOP) region were qualitatively and quantitatively evaluated microbiologically at various ripening times. Viable counts were performed after inoculation on appropriate selective media for aerobic mesophiles and proteolytic and lipolytic microflora, as well as lactococci, lactobacilli, species of Enterobacteriaceae, lactic streptococci, staphylococci, and yeasts. Members of the Enterobacteriaceae and lactic acid bacteria were the predominant microbial groups on all dairy farms throughout maturation; the latter are probably the microbial group responsible for most proteolytic and lipolytic breakdown in Serra da Estrela cheese. The microbial groups whose numbers were most affected by dairy-to-dairy variation were species of Enterobacteriaceae staphylococci, and enterococci, which are the most critical groups in terms of health hazards. It is therefore suggested that tighter control should be implemented at the level of choice of raw materials, in milk-handling practices, and in general throughout the manufacturing process in attempts to standardize production and consistently reduce microbiological risks (even though the distinctiveness of a few final organoleptic characteristics may somehow be reduced.
- Contribution of wild strains of lactic acid bacteria to the typical aroma of artisanal cheesePublication . Tavaria, Freni; Ferreira, A. CĂ©sar Silva; Malcata, F. XavierVolatile fatty acids (VFAs) are major contributors to the aroma profile of Serra da Estrela cheese. The impact of the dominant VFAs to the overall aroma perception was evaluated in a sensory test by a panel. The contribution of wild strains of lactic acid bacteria isolated from mature Serra da Estrela cheese to its volatile free fatty acid profile was also assessed. For this purpose, experimental cheeses manufactured according to the traditional protocol, but specifically added with starter cultures were analysed. Cheeses manufactured with deliberate inclusion of Lactobacillus plantarum as adjunct possessed aroma characteristics essentially similar to those manufactured artisanally, but with higher amounts of VFAs â thus meaning that this strain may help reduce ripening time in this cheese variety.
- Application of chitosan in the textile industry to control microbial growthPublication . Tavaria, F. K.; Soares, J.; Oliveira, V.; Silva, R.; Morgado, J.; Malcata, F. X.; Pintado, M. E.