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Alternative cheesemaking methods with raw ewes’ milk – microbiological, chemical, textural and sensory characteristics

Publication . Reis, Patrícia J. M.; Tavaria, Freni K.; Malcata, F. Xavier

Serra da Estrela cheese was manufactured using a novel, customised apparatus – designed to meet the specialty cheese’s specifications, and the resulting product was compared with that obtained via traditional manufacture in the same dairy. Semiindustrial cheesemaking led to a significantly (p<0.05) higher fat content in the final cheeses, with favourable consequences in terms of flavour and consumer acceptability – and significantly (p<0.05) lower viable numbers of (unwanted) enterococci in the matured cheese. Textural characteristics were broadly similar. Proteolysis was significantly (p<0.05) faster, but it was more variable in artisanal than in semi-industrial cheeses. The latter received significantly (p<0.05) better scores for texture, but lower scores for flavour. However, both products were within the specifications set forth by national regulations pertaining to Serra da Estrela PDO cheeses, so the novel apparatus is rather promising towards improved small-scale cheesemaking.

2010Journal article

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Influence of abiotic factors on the antimicrobial activity of chitosan

Publication . Tavaria, Freni K.; Costa, Eduardo M.; Gens, Eduardo J.; Malcata, Francisco Xavier; Pintado, Manuela E.

In an effort to bypass the adverse secondary effects attributed to the traditional therapeutic approaches used to treat skin disorders (such as atopic dermatitis), alternative antimicrobials have recently been suggested. One such antimicrobial is chitosan, owing to the already proved biological properties associated with its use. However, the influence of abiotic factors on such activities warrants evaluation. This research effort assessed the antimicrobial activity of chitosan upon skin microorganisms (Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli) in vitro when subject to a combination of different abiotic factors such as pH, ionic strength, organic acids and free fatty acids. Free fatty acids, ionic strength and pH significantly affected chitosan's capability of reducing the viable numbers of S.aureus. This antimicrobial action was potentiated in the presence of palmitic acid and a lower ionic strength (0.2% NaCl), while a higher ionic strength (0.4% NaCl) favored chitosan's action upon the reduction of viable numbers of S.epidermidis and E.coli. Although further studies are needed, these preliminary results advocate that chitosan can in the future be potentially considered as an antimicrobial of choice when handling symptoms associated with atopic dermatitis.

2013Journal article

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Chitosan: antimicrobial action upon staphylococci after impregnation onto cotton fabric

Publication . Tavaria, F.K.; Soares, J.C.; Reis, I.L.; Paulo, M.H.; Malcata, F.X.; Pintado, M.E.

Background: High levels of viable Staphylococcus aureus, which are often found on inflamed skin surfaces, are usually associated with atopic dermatitis. Textiles, owing to their high specific surface area and intrinsic hydrophilicity, retain moisture while also providing excellent environmental conditions for microbial growth and proliferation. Recently, a number of chemicals have been added to textiles, so as to confer antimicrobial activity. Aims: To evaluate the antimicrobial action of chitosan upon selected skin staphylococci. Methods and Results: We isolated staphylococci from normal skin of 24 volunteers and studied their survival upon contact with chitosan-impregnated cotton fabric. Low and high molecular weight chitosans were used at two concentrations; all four did effectively reduce the growth of some staphylococci (namely Staph. aureus), by up to 5 log cycles, thus unfolding a potential towards control and even prevention of related skin disorders. Conclusion: Our data suggest an effective, but selective antibacterial action of chitosans towards skin bacteria. Significance and Impact of the Study: The possibility to use a natural biopolymer incorporated in a textile to alleviate and even treat some of the symptoms associated with this skin condition may raise an alternative to existing medical treatments. The selectivity observed prevents full elimination of bacteria from the skin surface, which is an advantage.

2012Journal article

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Anti-proliferative, anti-inflammatory, anti-ulcerogenic and wound healing properties of chitosan

Publication . Tavaria, Freni; Jorge, Michelle P.; Lúcia T.G. Ruiz, Ana; Pintado, M. E.; Carvalho, João E.

In this study, anti-inflammatory, wound healing and anti-ulcerogenic properties of chitosan were evaluated ‘in vivo’ using wistar rats and swiss adult mice and the anti-proliferative activity was tested ‘in vitro’. The tested chitosans displayed no anti-proliferative or anti-inflammatory properties. The cytotoxic activity of chitosan was found to be non-existent towards eight tumoral cell lines and no significant differences were found in the ear edema (anti-inflammatory model) induced by croton oil and chitosan groups. However, chitosan showed good anti-ulcerative and wound healing abilities. Low molecular weight (LMW) chitosan effectively reduced ulcerative wounds induced by ethanol, while high molecular weight (HMW) chitosan helped retain the stomachal folds rendering a gastro protective effect. These results suggest that chitosan can potentially be used in the treatment of peptic ulcers. HMW chitosan also potentiated the healing process both in normal and diabetic rats, probably without induction of fibroblast growth but via collagen synthesis

2016Journal article

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