178,198 research outputs found
NATURAL INDICO FROM ISATIS TINCTORIA L. FOR THE VALORISATION OF SICILIAN CROPS
No full textIsatis tinctoria L. or woad (Brassicaceae) is an upright herbaceous biennal species up to 120 cm in
height. It is in Mediterranean counlries, a common plant cultivated through out centuries to produce
the blue dye indigo. With increasing concem for sustainability and a demand from consumers for
naturally sourced products, there is a revival of interest in naturai indigo as an agricultural crop
produci. Indigo is formed after the extraction of indigo precursors in the leaves of these plants:
mainly isatans in woad These compounds are extracted by steeping leaves in warm water. With
woad, the addition of alkali to the steep water releases free indoxyl, which forms indigo after a
vigorous aeration. Indigo is hydrophobic and insoluble in water, so that it sedimcnts readily, and the
solid indigo can be readily washed and dried. Indigo is synthesized from two precursor molecules of
indoxyl, deriving from plant secondary metabolism. Recently clarified the nature of indigo
precursors in woad (Isatis tinctoria L.), by identifying the major indoxyl glycoside as isatan A
(indoxyl-3-O-(60-O-malonyl-b-D-ribohexo-3-ulopyranoside)), and by correcting the structure of the
related isatan B (indoxyl-3-0-b-D-ribohexo-3-ulopyranoside). The seasonal variation of indoxyl
glyeosides in woad leaves was investigated and the influence of various post-harvest treatments was
studied and Isatans A and B disappeared completely when the leaf material was submitted to a
conventional drying process. In contrast, the indican coment in leaves increased significantly, and
the extent of this increase was temperature-dependent. These precursor can be identified and
quantified by HPLC method since their quantity in dependent on the species and the harvest period.
The modem extraction method of indigo from woad uses the water solubility of the indigo
precursors in steeping the leaves in hot water. The precursors are broken down to indoxyl and sugar
moieties by endogenous enzymes in plant (glycosidases), but in the extraction method this is done
by alkali with aeration. The purity of plant-derived indigo even with the modem extraction method
is somewhat low when compared to the synthelic indigo. Naturai indigo contains besides indigo,
impurities such as indirubin, indigo-brown, indigo gluten and minerai matter. Several authors
indicate that indigo can be extracted from woad with a purity of 90% if three conditions are met: the
leaves contain a sufficiently high yield of indigo precursors; the leaves are rinsed free of soil; and
the indigo is sedimented in an acid medium
REVERSIBILITY OF BROMONIUM ION FORMATION AND ITS EFFECT ON OLEFIN REACTIVITY IN ELECTROPHILIC BROMINATION - NEW EVIDENCE FROM THE 5H-DIBENZ[B,F]AZEPINE SYSTEM
No full textAssessment of B-glucosidase activity in selected wild strains of Oenococcus oeni for malolactic fermentation.
No full textA remarkable variability in the β-glucosidase activity was observed between 10 wild strains of Oenococcus oeni isolated from wines of the Valpolicella area. The activity occurred in both whole and sonicated cells (intercellular and parietal activities) but not in the supernatants of the cultures. The properties of β-glucosidase produced by DSTVR 7 and 10 strains include its activation in the presence of ethanol. These strains retained the enzyme activity at oenological conditions (pH value, temperature and ethanol) and showed good malolactic performance when inoculated in wine. None of the tested strains possessed anthocyanase activity
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Production and characterization of glicosidases from Aspergillus terreus using "pastazzo" as inductor
No full text
EFFECTS OF THERMAL TREATMENTS ON PECTINESTERASE ACTIVITY DETERMINED IN BLOOD ORANGES JUICES.
No full textSpagna e Portogallo, gemelli diversi
No full textAnalisi in prospettiva storica e di geopolitica culturale dei rapporti tra Portogallo e Spagna. Il quadro che emerge attesta la presenza di un forte "comune" tra i due paesi iberici, all'interno delle spinte centrifughe che caratterizzano le rispettive narrative di nazione
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