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Análise e caracterização de perfis voláteis de méis com e sem aromatização
Get PDFMestrado em Bioquímica - Bioquímica AlimentarO mel é uma substância doce natural produzida pelas abelhas Apis mellifera. Os tipos de mel obtidos de diferentes origens florais apresentam aromas e sabores distintos devido à sua diferente composição volátil. Apesar de estarem presentes em baixas concentrações, os compostos voláteis contribuem para o aroma e para as propriedades benéficas do mel.
O objetivo deste estudo foi a caracterização da composição volátil de seis méis aromatizados (canela, chocolate, limão, menta, picante e salgado) e três não aromatizados, fornecidos pela marca Beesweet. Para os méis não aromatizados (mel base, inverno e verão), procedeu-se também à análise polínica para determinar a respetiva origem botânica.
As amostras de mel foram caracterizadas de acordo com os seus parâmetros físico-químicos (pH e atividade da água) e pela capacidade antioxidante. Todas as amostras apresentaram valores dentro dos intervalos de referência. Algumas aromatizações (canela, chocolate, salgado e limão) contribuíram para um aumento da atividade da água. No que diz respeito à capacidade antioxidante, nas três amostras de mel sem aromatização, a que apresentou uma maior atividade foi o mel verão (8,25 μM de equivalentes de trolox/g de mel); das amostras de méis aromatizados foram a chocolate (8,01 μM de equivalentes de trolox/g de mel) e limão (6,95 μM de equivalentes de trolox/g de mel).
Pela análise polínica foi possível verificar que, das três amostras de mel sem aromatização, só uma pode ser classificada como mel monofloral, apresentando 89,1% de pólen de Eucalytus spp (mel inverno) e as restantes como méis multiflorais.
A extração de compostos voláteis do mel foi realizada por microextração em fase sólida em espaço de cabeça e cromatografia em fase gasosa acoplada à espetrometria de massa com quadrupolo (HS-SPME/GC-qMS). No mel monofloral foi possível identificar compostos característicos do eucalipto, como o nonanal, o p-menta-1,5,8-trieno e o aromadendreno, sendo este último apenas identificado neste mel. No mel base, os compostos que apresentaram maiores áreas cromatográficas foram o nonanal e decanal. Já no mel verão os compostos que se destacaram foram o nonanal e 1,1,6-trimetil-1,2-di-hidro-naftaleno. Nas aromatizações chocolate, picante e salgado, o composto que se destacou foi o nonanal, estando associado a aromas cítricos e picantes. Nos méis menta e canela foi o composto 1,8-cineol e no mel limão o limoneno, estando associados a aromas agradáveis e a possíveis propriedades benéficas. As aromatizações canela, limão e menta contribuíram para um aumento significativo dos compostos terpénicos, apresentando 18, 12 e 11 compostos, respetivamente, em comparação com o mel base que apresenta 5. Uma presença adicional destes compostos terpénicos confere aromas com descritores frutados, doces, picantes e cítricos a um mel base muito neutro em termos de aroma.
O estudo do perfil volátil permitiu a identificação dos principais compostos que contribuem para o aroma dos méis. Pela análise polínica foi possível verificar quais as famílias botânicas que deram origem aos méis.Honey is the natural sweet substance produced by Apis mellifera bees. The types of honey obtained from different floral origins present distinct aroma and flavour due to their different volatile composition. Despite present in low concentrations, volatile compounds contribute to the aroma and to the beneficial properties of honey.
This study aims to examine the volatile composition of six flavoured honeys (cinnamon, chocolate, lemon, mint, spicy and salty) and three unflavoured honeys provided by Beesweet. The pollen analysis is also taken into consideration to determine the floral origin, in the case of unflavoured honeys (Base, Winter and Summer honey).
The honey samples were characterized according to their physicochemical parameters (water activity and pH) and antioxidant activity. All samples presented values within the reference ranges. Certain varieties of flavoured honey (cinnamon, chocolate, lemon and salty) contributed to an increase in water activity. The unflavoured honey that presented the highest antioxidant activity was the Summer honey (8.25 μM trolox equivalent/g of honey); in the case of flavoured honeys, the highest antioxidant activity was found in the chocolate (8.01 μM trolox equivalent/g) and lemon (6.95 μM trolox equivalent/g) varieties.
After conducting a pollen analysis of the three samples of unflavoured honey, one sample was classified as monoflora, presenting 89.1% of Eucalytus spp pollen (Winter honey), and the others as multifloral honeys.
The extraction of volatile compounds from honey was performed using the headspace solid phase microextraction combined with gas chromatography-quadrupole mass spectrometry (HS-SPME/GC-qMS). In monofloral honey, it was possible to identify eucalyptus compounds such as nonanal, p-mentha-1,5,8-triene and aromadendrene (this last compound was only observed in this type of honey). In the Base honey, the compounds with higher chromatographic areas were nonanal and decanal. In the Summer honey, the most prominent compounds were nonanal and 1,1,6-trimethyl-1,2-dihydronaphthalene. In the chocolate flavoured honey and spicy and salty variations, the compound with the highest value was nonanal, presenting citrus and spicy aromas. In the cinnamon and mint flavoured honeys, the highest values were for the 1,8-cineole compound, while the lemon flavoured honey had the presence in higher amount of limonene, both associated with pleasant aromas and potentially beneficial properties. The cinnamon, lemon and mint flavoured honeys contributed to a significant increase in the terpene compounds (18, 12, and 11 compounds, respectively), in contrast to the base honey that has 5 compounds. An additional presence of these terpene compounds confers fruity, sweet, spicy and citric flavours to the honey, which had a very neutral aroma.
The study of the volatile profile allowed the identification of the main compounds that contribute to the honey aroma. From the pollen analysis it was possible to verify their botanical families
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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