Anthocyanin Copigmentation: Evaluation, Mechanisms and Implications for the Colour of Red Wines

[EN]Copigmentation is the main colour-stabilizing mechanism in plants and in food products of vegetable origin. It is a spontaneous and exothermic process that consists of the stacking of an organic molecule, called copigment, on the planar polarizable moieties of the anthocyanin coloured forms. Although this phenomenon has long been described, there are some aspects that are still not well understood or controversial like the nature of the interaction pigment to copigment, the way to quantify the extent of the process, its effect on other anthocyanin properties like astringency or reactivity. In this article a review of the most significant advances achieved in the last years in the field of intramolecular and intermolecular copigmentation is presented. Also, the most recent findings regarding wine copigments and their effects on the colour of red wines are revised

Desarrollo e implementacion de recursos audiovisuales en la docencia del grado en Ingeniería.

Memoria ID-354. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2013-2014.[ES] El informe que se presenta es el resultado del diseño, desarrollo y evaluación de material docente audiovisual para la impartición de la docencia teórica de la asignatura Ingeniería de las Industrias Agroalimentarias II en la E.P.S. de Zamora. Con ello se pretende utilizar de forma didáctica los medios audiovisuales con una finalidad, no sólo, motivadora y acorde con el contexto real sino también que facilite la comprensión de los contenidos objeto de estudio. El proyecto permite asimismo, conocer cómo estos materiales inciden en el proceso de enseñanza-­‐ aprendizaje en general, y en particular en la enseñanza de las asignaturas de ingeniería. Por otra parte, se perseguía poder desarrollar el proyecto con un coste cero de material (no se solicitó dotación económica), por lo que se recurrió a la utilización de material disponible online y programas informáticos de software abierto. El material elaborado se ha incorporado a la docencia de la asignatura como metodología activa para el aprendizaje., estableciendo así un nuevo ambiente de aprendizaje

Creación y validación de rúbrica para la evaluación entre iguales de trabajos en la asignatura biotecnología alimentaria

Memoria ID-182. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2019-2020

Coupling reactions between flavylium ions and catechin

[EN] In order to model natural polymeric pigments present in old red wines, new covalent adducts have been synthesized upon condensation of synthetic flavylium ions (models of anthocyanins) with catechin (model of tannins) in the presence and in the absence of acetaldehyde. These new pigments have been investigated by 1D and 2D NMR, HPLC, FAB-mass and UV-visible spectroscopies and molecular modelling. The two flavylium salts used in this work (3,4'-dimethoxy-7-hydroxyflavylium chloride and 5,7-dihydroxy-3,4'-dimethoxyflavylium chloride) display quite different reactivities toward catechin. The electronic donating effect of the catechin moiety and the formation of noncovalent dimers in acidic aqueous or methanolic solution should be mainly responsible for the improved stability of the flavylium chromophore in the new pigments

Multivariate analysis of sensory data of Vitis vinifera L. cv. Graciano during ripening. Correlation with the phenolic composition of the grape skins

The aim of this work was to evaluate sensory changes in grape skins during ripening and to obtain a correlation with their phenolic composition. Flavan-3-ols (monomers and dimers), prodelphinidins, hydroxybenzoic acids, hydroxycinnamic acids, anthocyanins and flavonols were determined by HPLC-DAD-MS. In addition, skin dilaceration, tannic intensity, astringency, acidity, aroma intensity (AI) and type of aroma were evaluated. Multivariate analysis showed the evolution of these samples during ripening and the relationship among sensory scores and phenolic composition of grapes skins. Skin dilaceration, type of aroma and to a lesser extent AI tend to increase during ripening. The contents in the phenolic compounds in grape skins present a similar pattern to the aforementioned sensory parameters. Nevertheless, tannic intensity, astringency, dryness and acidity present an opposite pattern which indicates a decrease of these sensory scores during ripening.Ministerio de Ciencia e Innovación AGL2008-05569-C02-01Consolider-Ingenio 2010 Programme CSD2007-0006

Stability of pelargonidin 3-glucoside in model solutions in the presence and absence of flavanols

The stability of pelargonidin 3-g1ucoside (Pg3g1uc), the main anthocyanin in strawberry, has been studied in model citrate solutions (PH 3.5, 25°C) in the absence and presence flavanols (catechin and procyanidin B3) and/or oxygen. Changes in the solutions were monitorized by HPLC-DAD/MS and UV-visible spectra.Governo Português e Fundo Social Europeu através da medida n.º 5/Acção nº5.3 - PRODEP (III)(referência 5.3/N/199.006/00-Doutoramento)

New 3-Deoxyanthocyanidins from Leaves of Arrabidaea chica

[EN]Two new 3-deoxyanthocyanidins, 6,7,3 ,4 -tetrahydroxy-5-methoxyflavylium and 6,7,4 -trihydroxy-5- methoxyflavylium, and the pigment carajurin, which has been previously identified, were isolated from dried leaves of Arrabidaea chica, a creeper native to the American tropics. The structures of the components were elucidated by 1H- and 13C-NMR spectroscopy and HPLC-MS, including X-ray crystallographic analysis for carajurin

Physico-Chemical and Chromatic Characterization of Malvidin 3-Glucoside-vinylcatechol and Malvidin 3-Glucoside-vinylguaiacol Wine Pigments

[EN] The physicochemical and chromatic features of malvidin 3-glucoside-vinylcatechol (PA1) and malvidin 3-glucoside-vinylguaiacol (PA2) adducts were investigated. Important differences between both pigments were observed. In the investigated pH range (2.0−4.5), our results suggest that PA1 could be considered as a noncovalent dimer of two pyranoflavylium ions (AH)2 which undergo a hydration reaction in two successive steps, with no proton transfer. In contrast, only proton transfer equilibrium between the pyranoflavylium ion and the quinonoid bases was observed for PA2. The hydration and acidity thermodynamic constants of both pyranoanathocyanins were determined by UV−vis spectroscopy. Pigment PA1 was shown to be less sensitive to bisulfite addition than to water addition, and PA2 seems to be largely insensitive to both water and bisulfite additions. The binding constants for the interaction between the pigments and (+)-catechin in aqueous solution and the changes in the CIELAB parameters that it provoked were also determined. The huge increase in the absorption of the pyranoflavylium ion of PA2 when it binds catechin has no equivalent for anthocyanins and nicely outlines the potential of pyranoanthocyanins in the expression of natural colors

Schizanthus grahamii and Schizanthus hookeri. Is there any relationship between their anthocyanin compositions and their different pollination syndromes?

[EN] Three different pollination syndromes (bee, hummingbird and moth-pollination syndromes) have been described for the different species of the genus Schizanthus Ruiz & Pav. (Solanaceae). Two closely related species from a phylogenetic point of view, Schizanthus grahamii and Schizanthus hookeri, show hummingbird and bee-pollination syndromes, respectively. One of the traits used to assign these pollination syndromes is the colour of the petals, which is red in S. grahamii and bluish-pink in S. hookeri. The objective of this work was to establish the differences in the anthocyanin composition of these two Schizanthus species that contribute to the different pollination syndrome. Identification of the pigments was carried out from the chromatographic and spectral data supplied by the HPLC-DAD-MSn analyses of the samples. Alkaline and acid hydrolyses were also performed in the extracts and in some isolated compounds in order to confirm the identities. First difference between these two species was found in the total anthocyanin content, which was about 13-fold higher in S. grahamii than in S. hookeri. Furthermore, the major peak was also different in both cases, thus explaining quantitative and qualitative colour differences between species. Delphinidin 3-O-rutinoside represented ca. 72% of the total area in S. grahamii and petanin (Petunidin 3-O-p-coumaroylrutinoside-5-O-glucoside) accounted for almost 62% of the total area in S. hookeri. The presence of the p-coumaroylrutinosyl moiety in the petanin makes the intramolecular copigmentation possible, thus conferring the bluish-pink hue to the petals of S. hookeri. Delphinidin 3-O-rutinoside is in turn responsible for the red colour exhibited by the petals of S. grahamii and along with other floral traits, responsible for the attraction of hummingbirds to the plant. Pigments structurally related to petanin, which have been often detected in other genus of Solanaceae, were detected in both species and in similar contents, supporting results from previous studies that pointed to a bee-pollinated common ancestor for both species that further specialised acquiring traits attractive to hummingbirds and among them, red colour of the petals which is mainly supplied by delphinidin 3-O-rutinoside

Changes in the detailed pigment composition of red wine during maturity and ageing

[EN] The qualitative and quantitative changes produced, during maturation and ageing, in the pigment composition of a red wine made from Vitis vinifera cv Tempranillo grapes have been studied. In order to determine the detailed composition of the main pigment families involved in the colour changes, a fractionation of the samples has been carried out. One-hundred and twenty-nine different compounds have been identified and their evolutions with wine age have also been established. The data obtained in the analyses of the fractions by high performance liquid chromatography–diode array detection coupled to mass spectrometry (HPLC–DAD–MS) have been used in pigment identification. In order to confirm the identity of some of these compounds, their syntheses have also been carried out. As far as we know, compounds originated by acylation of the monoglucosides of the anthocyanins with lactic acid as well as 3,7-diglucosides of anthocyanins have, among others, been reported here for the first time. The moments of appearance and disappearance of all the detected compounds have also been established as well as the changes in the levels of the different pigment families and subfamilies originated as a consequence of maturation and ageing of the wine in barrels or in bottles. As wine became older, the percentages of anthocyanins decreased slightly, whereas that of the anthocyanin-derived pigments increased and, above all, compounds providing the wine with orange hues (pyranoanthocyanins). In the last sample, they represented 70% of the anthocyanin-derived pigments. On the contrary, the percentage of compounds providing bluish hues to the wine, direct and acetaldehyde-mediated flavanol–anthocyanin condensation products, decreased. This change in the nature of the anthocyanin-derived pigmentwould explain the colour change observed in the samples, from purple towards orange hues