Browsing by Author "Artilheiro, Ana Sofia"
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- Avaliação da atividade antimicrobiana de óleos essenciais de mentha sppPublication . Artilheiro, Ana Sofia; Amaral, J.S.A maioria das doenças de origem alimentar são causadas por microrganismos, incluindo bactérias, bolores, protozoários e vírus. Com vista a controlar o crescimento microbiano em alimentos, a indústria alimentar frequentemente recorre ao uso de aditivos, nomeadamente antimicrobianos cuja utilização está devidamente autorizada para esta finalidade. Contudo, recentemente tem-se verificado um interesse crescente na exploração de alternativas que permitam prevenir doenças de origem alimentar e promovam a extensão do prazo de validade dos alimentos. Entre estas, destacam-se os óleos essenciais por frequentemente exibirem propriedades antimicrobianas e/ou antifúngicas. Neste estudo foi testada a atividade antimicrobiana de óleos essenciais de plantas aromáticas utilizadas na alimentação humana, nomeadamente Mentha arvensis e Mentha piperita, sobre bactérias Gram-positivas (Bacillus cereus, Staphylococcus aureus) e Gram-negativas (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa). No caso de M. piperita avaliaram-se dois óleos essenciais, um obtido por hidrodestilação em aparelho de clevenger e outro comercial, enquanto para M. arvensis testou-se apenas um óleo comercial. De forma geral, os óleos essenciais revelaram forte capacidade inibitória contra as bactérias gram-positivas e gram-negativas estudadas, à exceção de Pseudomonas aeruginosa que mostrou ser resistente a todos os óleos testados. Comparativamente ao antibiótico utilizado como controlo positivo, penicilina ou canamicina, em alguns casos foram obtidos halos de inibição superiores para os óleos essenciais. Das duas espécies de menta avaliadas, o óleo de M. piperita foi o mais eficaz, apresentando resultados similares para o óleo comercial e o extraído em laboratório.
- Evaluation of the antioxidant and antibacterial activity of spearmint (Mentha spicata L.)Publication . Moreira, Cláudia; Artilheiro, Ana Sofia; Afonso, Maria João A.P.S.; Amaral, Joana S.Aromatic herbs and spices have been used for centuries in gastronomy for seasoning and flavouring purposes. Additionally, several of these herbs are also used in traditional medicine due to their composition in bioactive compounds. In order to control the microbial growth in foods, the food industry often resorts to the use of additives, namely of authorised preservatives. However, recently there has been a growing interest towards the use of alternatives, namely natural additives and extracts from plants, that would allow preventing foodborne diseases and promoting the extension of the shelf life of foods [1]. Due to its potential activity against foodborne pathogens and foodspoilage bacteria and its better acceptability by consumers who are increasingly demanding for more “natural” foods, the use of essential oils can be an interesting alternative to substitute, at least partially, synthetic preservatives [2]. Different types of mints are included among the most widespread perennial aromatic herbs, with different species being also used in folk medicine. Among those, Mentha spicata L., commonly called spearmint or garden mint, is widely used in as a flavouring agent in foods, in particular in the European cuisine. This plant is also frequently used in infusions and in folk mainly for its digestive, carminative, antispasmodic and diuretic properties [3]. In this work, the total content of phenolic compounds and of flavonoids, reducing power and antioxidant activity (in vitro measurement of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity) of spearmint (Mentha spicata) methanolic extracts were evaluated using spectrophotometric techniques. Additionally, the antibacterial activity of the essential oil extracted from the plant by hydrodistillation using a Clevenger apparatus, was also evaluated by the agar-diffusion method against different Grampositive bacteria (Bacillus cereus, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa). Preliminary results of this study suggest that the inclusion of spearmint as a seasoning/flavouring agent in different dishes or consumed in the form of infusion can offer health benefits due to their antioxidant capacity. Additionally, the essential oil from Mentha spicata showed a significant inhibitory capacity against all studied Gram-positive and Gram-negative bacteria, with the exception of Pseudomonas aeruginosa, which showed to be resistant. Compared to the antibiotics used as a positive control, for some bacteria, higher inhibition halos were obtained for the essential oil. Therefore, the use of spearmint as a condiment in gastronomy may be beneficial from the point of view of food safety and food shelf-life improvement.