42 research outputs found
Microsatellites for the Amazonian Fish Hypophthalmus marginatus
We isolated 41 and characterized 17 microsatellite loci for evaluating the genetic structure of the Amazonian fish Hypophthalmus marginatus, from the Tocantins and Araguaia River in the Eastern Amazonia. Of the 17 selected microsatellite sequences, 15 were dinucleotide repeats, 9 of which were perfect (5â31 repetitions) and 6 were composite motifs. Among these 17 microsatellites, only two were polymorphic. The average number of alleles (Na) observed in the five examined populations ranged from 3.5 to 4.5, while the average observed heterozygosity (Ho) ranged from 0.3 to 0.6. The allelic frequency was less homogeneous at the locus Hm 5 than that for the Hm 13. Genetic diversity was measured in three upstream and two downstream populations under the influence of the TucuruĂ Hydroelectric Dam. Our findings provide evidence for low levels of genetic diversity in H. marginatus of the Tocantis basin possibility related to the Dam construction. The Fst and Rst analysis fits well with migratory characteristics of H. marginatus, suggesting the existence of a gene flow mainly in the upstream or downstream directions. To test the hypothesis that the Dam was responsible for the detected reduction on this species genetic diversity, a large number of genetic markers are recommended, covering geographic distribution range of the fish species
Kinetics of mass loss of arabica coffee during roasting process
Roasting is one of the most complex coffee processing steps due to simultaneous transfers of heat and mass. During this process, beans lose mass because of fast physical and chemical changes that will set color and flavor of the commercial coffee beverage. Therefore, we aimed at assessing the kinetics of mass loss in commercially roasted coffee beans according to heating throughout the processing. For that, we used samples of 350-g Arabica coffee processed grains with water content of 0.1217 kga kg-1, in addition to a continuous roaster with firing gas. The roaster had initial temperatures of 285, 325, 345 and 380 °C, decreasing during the process up to 255, 285, 305 and 335 °C respectively. Mass loss was calculated by the difference between grain weight before and after roasting. We observed a linear variation directly dependent on roaster temperature. For each temperature during the process was obtained a constant mass loss rate, which was reported by the Arrhenius model with r2 above 0.98. In a roaster in non-isothermal conditions, the required activation energy to start the mass loss in a commercial coffee roasting index was 52.27 kJ mol -1.A torrefação Ă© uma das etapas mais complexa do processamento do cafĂ© devido Ă
transferĂȘncia simultĂąnea de calor e massa, em que os grĂŁos perdem massa devido Ă rapidez das
mudanças fĂsicas e quĂmicas, necessĂĄrias para produzir a cor e o aroma do cafĂ© comercial. Assim,
objetivou-se com este trabalho determinar a cinética da perda de massa dos grãos de café torrados
comercialmente em função da temperatura do processo. Foram usadas amostras de 350 g de grãos
beneficiados de café aråbica com teor de ågua de 0,1217 kga kg-1
. Usou-se um torrador com queima
de gĂĄs constante e temperaturas iniciais de 285; 325; 345 e 380 °C, que diminuĂram durante a
operação até equilibrar-se em 255; 285; 305 e 335 °C, respectivamente. A perda de massa foi
calculada a partir do peso dos grãos antes e depois da torração, sendo observada uma variação linear
dependente diretamente da temperatura do torrador. Para cada temperatura do processo, foi obtida
uma taxa constante de perda de massa, que foi relacionada pelo modelo de Arrhenius com r2
acima
de 0,98. Em condiçÔes não isotérmicas do torrador, a energia de ativação necessåria para iniciar a
perda de massa, em Ăndices de torração comercial do cafĂ©, foi 52,27 kJ mol-1
.Universidad de Costa Rica/[]/UCR/Costa RicaConselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico/[]/CNPq/BrasilCoordenação de Aperfeiçoamento de Pessoal de NĂvel Superior/[]/CAPES/ BrasilFundação de Amparo Ă Pesquisa do Estado de Minas Gerais/[]/FAPEMIG/BrasilUCR::VicerrectorĂa de InvestigaciĂłn::Unidades de InvestigaciĂłn::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS