1,720,993 research outputs found
γ-Glutamyltranspeptidase-catalyzed enzymatic synthesis of flavour enhancers from Allium sp.
No full textThe use of flavour enhancers in the food industry could be beneficial for several reasons: they ensure homogeneity of the
final products, reduce costs for condiments and favor consumer's acceptance. On the other hand, the consumer's attention for
convenient, minimally-processed, nutritious, healthy, yet tasty food prompts the food industry to an accurate choice of the
ingredients. In this scenario, naturally occurring kokumi substances could play an important role. Kokumi is a japanese term that refers to mouthfulness, thickness and long-lasting savory sensations. Kokumi substances are represented mainly by gamma-glutamyl derivatives of amino acids. They are nearly tasteless for themselves, but they elicit a strong taste sensation,
expecially in conjunction with protein-rich food [Dunkel 2007]. In vegetables of the genus Allium, kokumi substances were
identified in gamma-glutamyl derivatives of S-alkyl and S-alkenyl cysteines and their S-oxides [Ueda 1990].There is a number of
difficulties connected with the supplying of these materials. Isolation from natural sources is laborious, and their content in
vegetables varies with cultivation and storage. In addition, upon crushing the plant, they are enzymatically degraded. The
chemical synthesis is not economical, due to the need of protection/deprotection steps. We exploited recently the enzymatic synthesis at the laboratory scale of the gamma -glutamyl derivatives of S-allyl cysteine, S-methyl cysteine and methionine, catalyzed by a commercially available mammalian GGT [Speranza 2012]. In this communication we report that such flavour enhancers can be obtained as well by using a purified, home-made bacterial GGT from Bacillus subtilis, a GRAS (Generally Recognized As Safe) organism, suited to food processing
Gamma-glutamyltranspeptidase-catalyzed chemoenzymatic synthesis of naturally occurring flavour enhancers
No full textγ-Glutamyl derivatives of S-substituted cysteines are naturally occurring flavor enhancers found in garlic and in other plants of the genus Allium. A straightforward enzymatic synthesis of γ-glutamyl-S-alkyl and S-alkenyl cysteines based on a transpeptidation reaction catalyzed by a purified, home-made bacterial γ-glutamyl transpeptidase (GGT) from a GRAS organism (thus suited to food processing) has been developed
A New Synthetic Entry to 3-Carboxamido-4-carboxylic Acid Derivatives of Isoxazole and Pyrazole
No full textEthyl 2-amino-3-methoxycarbonyl-4-oxo-2-pentenoate (3) reacts with hydroxylamine or hydrazines to give isoxazole and pyrazole ortho-dicarboxylic acid esters 4 and 5, respectively. Partial hydrolysis of diesters 4 and 5 afforded the corresponding dicarboxylic acid monoesters 6 and 7. Amidation of the intermediate acid chlorides 8,9 followed by hydrolysis of 4-methylesters 10,11 gave the title compounds 1 and 2, respectively
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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