8,627 research outputs found
Further insights into the role of methional and phenylacetaldehyde in lager beer flavor stability
This work attempts to measure the importance of methional and phenylacetaldehyde on the flavor stability of beer, as direct participants or as indicators of aroma deterioration. A trained sensory panel
identified the most important descriptors related to the typical aroma of aged beer: “malty”, “honeylike”,
“cooked potato”, and “metallic”. By GC-olfactometry analysis, six aromatic zones related to
the selected descriptors were highlighted, and by using GC-MS techniques it was possible to identify
methional and phenylacetaldehyde as being responsible for two odor zones. The quantification of
these molecules in samples submitted to forced aging treatments showed that the levels of methional
and phenylacetaldehyde are dependent on the temperature of storage. Normal aged beers were
also analyzed, and it was observed that these compounds accumulate with time of storage.
Furthermore, these molecules were negatively correlated with the aroma quality of beer as evaluated
by a sensorial panel. To validate the sensory impact of these substances, a fresh beer was spiked
with these molecules and also with trans-2-nonenal, singly and in combination, and the similarity
value between samples and the aged beer was then determined. The highest value from the similarity
tests was 72% when the three compounds were added simultaneously. The combination of the two
Strecker aldehydes increases by 54% the degree of similarity, indicating the key role played by these
molecules in the aroma deterioration of beer. Finally, the kinetic parameters, Ea and k, were calculated,
and it was observed that the Arrhenius equation described well the temperature dependence of the
reaction rate constant. Measuring the concentration of methional and phenylacetaldehyde may provide
information about the key steps along the process that most affect the flavor stability of beer, which
may be useful in establishing the best storage conditions
Techno-economic assessment of a Synechocystis based biorefinery through process optimization
UID/EQU/00511/2019 "LEPABE-2-ECOINNOVATION"-NORTE-01-0145-FEDER-000005.Similar to oil, biological origin feedstock can be converted into a number of products allowing to recover the maximum value from the raw biological material, within what is nowadays called a biorefinery. Among other biological materials, microalgae are a very interesting biomass due to the high economic value of certain cellular components, such as carotenoids and polyunsaturated fatty acids. In this project, a genetically modified cyanobacteria, that produces ethanol as an extracellular product, was used as the basis of this study. In order to assess the optimal configuration of the biorefinery, different scenarios were designed, each one with different sequences of unit operations, equipment and products. With the design stage completed, an economic analysis was performed to choose the 2 scenarios with the best economic performance.publishersversionpublishe
Avaliação participativa de acessos de bucha vegetal.
Publicado também na Revista Brasileira de Agroecologia, v. 4, n. 2, 2009
The relationship between chemical of happiness, chemical of stress, leadership, motivation and organizational trust: a case study on Brazilian workers
This article discusses what happens in our body and the response in the organizational environment addressing the chemical of stress and the chemical of happiness from dopamine (motivation hormone); serotonin (lead hormone); and oxytocin (trust hormone), correlating these chemicals to measure the level of trust that Brazilian workers have in their leaderships. The seriousness of the study of the chemical of happiness in the organizational environment is largely due to the understanding that they perform several important functions, especially decision making, which favors the execution of tasks. Within this context, especially with regard to decision making, the study of the love hormone, triggered by positive emotions through the chemical of happiness, or contrary, through the release of high doses of cortisol, has been shown to be necessary in the factor of prevention of negative consequences that reflects on mental health, culture and organizational climate, causing conflicts among employees, impairing cognitive potential, creativity and problem solving, making employees work unmotivated, causing, for the most part, or turnover. In order to discuss this subject, the methodology used was the qualitative research of an exploratory nature and literature review that, together with the data collection, sought to address the objectives of this article.info:eu-repo/semantics/publishedVersio
Incidência de Colletotrichum graminicola em colmos de genótipos de milho.
A podridão do colmo, causada por Colletotrichum graminicola, é uma das mais severas doenças da cultura do milho no Brasil, principalmente se ocorrer após a fase de florescimento, por causar perdas significativas na produtividade. A melhor alternativa para o controle da doença é a utilização de cultivares geneticamente resistentes. O objetivo deste trabalho foi avaliar a incidência da podridão de colmo em híbridos comerciais de milho, tendo em vista a pouca disponibilidade de informações que permitam a utilização da resistência genética como estratégia para o controle desta doença. Foram avaliados 18 híbridos comerciais de milho, em três ensaios conduzidos nos anos de 2005, 2006 e 2007 na área experimental da Embrapa Milho e Sorgo, sob condições de inóculo natural. Em cada parcela foram coletados fragmentos do colmo de três plantas, sendo: o segundo entrenó acima do solo, o entrenó de inserção da espiga e o entrenó localizado abaixo do pendão. Quatro fragmentos de cada parte foram desinfestados e transferidos para placas de Petri contendo meio de farinha de aveia - ágar (FAA). As placas foram mantidas em câmara de incubação sob luz fluorescente contínua à temperatura de 25°C, seguindo-se a identificação e quantificação do patógeno após três a quatro dias de incubação. As menores incídências (abaixo de 30%) foram observadas nos híbridos BR201 e BR206 e a maior incidência (acima de 60%) detectada no híbrido BRS 1010. O patógeno foi detectado em todos os segmentos do colmo analisados, predominando, entretanto, no terço médio superior para a maioria dos híbridos avaliados. Apesar da variação observada entre os genótipos quanto à incidência da antracnose no colmo, nenhum híbrido pôde ser considerado como de altamente resistente ao patógeno
Low-energy electron scattering from methanol and ethanol
Measured and calculated differential cross sections for elastic (rotationally unresolved) electron scattering from two primary alcohols, methanol (CH3OH) and ethanol (C2H5OH), are reported. The measurements are obtained using the relative flow method with helium as the standard gas and a thin aperture as the collimating target gas source. The relative flow method is applied without the restriction imposed by the relative flow pressure conditions on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°–130°. There are no previous reports of experimental electron scattering differential cross sections for CH3OH and C2H5OH in the literature. The calculated differential cross sections are obtained using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Comparison between theory and experiment shows that theory is able to describe low-energy electron scattering from these polyatomic targets quite well
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