ABSTRACT
The aim of this work was to study the application of a stochastic algorithm to correlate the experimental data of island-type systems in ternary systems. Thermodynamic NRTL and UNIQUAC models were used to evaluate the activity coefficients. Results regarding the application of the stochastic algorithm were in good agreement with those presented in the current literature. However, generalization of the method proposed in the present work remained an intriguing and complex task so as to reach broad conclusions.
ABSTRACT
This study investigated the chemical composition of five different extracts of Aloysia triphylla and their activity against Aeromonas sp. The extracts were obtained from the dried leaves by pressurized CO2 extraction at 30, 50 and 70ºC, and 100, 150, and 200 bar, and analyzed by GC/FID and GC-MS. The antibacterial activity was assayed by the microdilution method. The tested microorganisms comprised seven Aeromonas isolates obtained from the kidney of infected silver catfish, Rhamdia quelen. The yield, chemical composition and antibacterial activity of the extracts were dependent on the extraction conditions. Mono and sesquiterpenoids were the major constituents of all the extracts and the highest extraction yield was obtained at 70ºC and 200 bar. A. triphylla presented moderate antibacterial activity against Aeromonas sp.
ABSTRACT
The use of compressed carbon towards extracting semi-volatile compounds present in maté leaves (Ilex paraguariensis St. Hil.) is due to the growing interest in mate constituents to develop new products in the cosmetic, pharmaceutical and food industries. The objective of this work was to assess the chemical distribution of semi-volatile compounds in 20 native populations of maté collected all over Brazil. The extracts of bulk samples (30 plants) of each population were obtained by the high-pressure carbon dioxide extraction technique, and analyzed by GC/MSD. The quantification of compounds (caffeine, theobromine, phytol, squalene, vitamin E, eicosane, pentatriacontane, and stigmasterol) showed significant variations within the different populations and compounds analyzed, which are not related to geographical origin or macroclimate characteristics. The results pointed out to the importance of genetic and local environmental factors on the chemical composition of this species.
A extração empregando dióxido de carbono a altas pressões em erva-mate (Ilex paraguariensis St. Hil.), tem sido justificada pelo crescente interesse desta matriz vegetal ou de parte de seus constituintes na formulação de novos produtos, tais como cosméticos e medicamentos, entre outros. Neste contexto, o objetivo do presente trabalho é avaliar a distribuição química de compostos semi-voláteis em 20 populações de erva-mate coletadas em toda área de distribuição desta espécie no Brasil. 30 plantas foram selecionadas para produzir a amostra de cada população. Os extratos de cada amostra foram obtidos por extração com dióxido de carbono a alta pressão e, posteriormente, foram analisados por CG/EM. A quantificação de alguns compostos semi-voláteis presentes nos extratos (cafeína, teobromina, fitol, esqualeno, vitamina E, eicosano, pentatriacontano e stigmasterol), apresentaram variações significativas entre as concentrações dos diferentes compostos analisados nas diferentes populações, os quais não estão relacionados com origem geográfica ou com características de macroclima. Os resultados apontam para a importância dos fatores genéticos e/ou fatores de microclima sobre a composição química desta espécie.
ABSTRACT
This work reports antimicrobial activity of oregano (Origanum vulgare) essential oil against several bacteria in sausage. The in vitro minimum inhibitory concentration (MIC) was determined for 9 selected aerobic heterotrofic bacteria. The antimicrobial activity of distinct concentrations of the essential oil on the basis of the highest MIC found was tested in a food system comprised of fresh sausage. Batch food samples were also inoculated with Escherichia coli with a fixed concentration and the time course of the product was evaluated with respect to the action of the different concentrations of essential oil. Sensory analysis were conducted, and results showed that the addition of oregano essential oil to sausage may be a promising route as bacteriostatic effect was verified for oil concentrations lower than the MIC.
O presente trabalho reporta resultados referentes à testes de atividade antimicrobiana do óleo essencial de orégano (Origanum vulgare) contra várias bactérias em lingüiça. A concentração inibitória mínima (CIM) foi determinada para 9 bactérias aeróbicas heterotróficas. Com base no maior valor encontrado da CIM, testou-se a atividade antimicrobiana para distintas concentrações do óleo essencial in lingüiça fresca. Amostras do sistema alimentar escolhido foram inoculadas com Escherichia coli numa determinada concentração e a evolução temporal do produto concernente ao crescimento microbiano foi monitorada avaliando-se o efeito das diferentes concentrações de óleos essencial aplicadas ao produto inoculado. Os resultados das análises microbiológica e sensorial mostraram que a adição do óleo essencial de orégano a linguiça fresca coloca-se como promissora tendo em vista os efeitos bacteriostáticos observados em baixas concentrações do óleo essencial, inferiores a CIM.