Effect of the presence of different oak ellagitannins in their own disappearance under oxidative or inert atmosphere

[EN] The disappearance of the C-glycosidic ellagitannins over time can occur even in absence of oxygen and their disappearance rate seems to be affected by the presence of other ellagitannins in the media. The objective of this work was to study the influence of the presence of other ellagitannins and/or oxygen on the individual evolution of the main oak ellagitannins in simple model systems in order to understand their behaviours in more complex media, such as wine. In all the studied conditions, vescalagin disappeared faster than castalagin, highlighting its greater reactivity. Oxygen increased the individual disappearance rate, as also occurred when more than one type of ellagitannin was present, above all if the additional ellagitannin(s) contained the same conformation in C1 as vescalagin. Experimental data were fitted to a kinetic model considering both the oxygen-dependent and oxygen-independent reactions, making possible the comparison between individual compounds in different scenarios.MINECO (Proyecto ref. AGL2017-84793-C2-1-R co-financiado por FEDER).Food Chemistr

Elaboración de árboles de decisión para mejorar el aprendizaje en el área de análisis de los alimentos

Memoria ID2023-208 Ayudas de la Universidad de Salamanca para la innovación docente, curso 2023-2024.[ES] El objetivo de este trabajo fue introducir una nueva metodología docente, basada en la elaboración de árboles de decisión, para fomentar y mejorar el aprendizaje activo en la asignatura de Nutrición y Bromatología (3er curso) del Grado de Farmacia, abordando así contenidos teóricos relacionados con el análisis de los alimentos. Uno de los temas incluidos en el análisis de alimentos es el “Análisis de carbohidratos en alimentos”, donde se explican los métodos utilizados para la extracción y separación de estos macronutrientes en alimentos, así como los métodos utilizados para su cuantificación. Este tema, en concreto, es uno de los más complejos para el estudiantado, puesto que existe una gran variedad de técnicas en función de la matriz donde se encuentren y del estado físico del alimento. A pesar del refuerzo al aprendizaje que puede suponer a los alumnos el trabajo del tema en los seminarios con casos prácticos, se siguen observando errores en la resolución de los problemas de análisis de carbohidratos en alimentos. Por este motivo, en el presente trabajo se planteó el diseño, por parte de los estudiantes, de árboles de decisiones para seleccionar las técnicas de análisis más adecuadas para la determinación de estos nutrientes en alimentos, y que, además, puedan ser de aplicación en diversas matrices

Flavanol-anthocyanin condensed pigments in plant extracts

Pigments resulting from the direct condensation of anthocyanins and flavanols are usually associated with reactions taking place during processing and storage of plant-derived foods and beverages and have been particularly studied in aged red wines. In this paper, small amounts of flavanol-anthocyanin condensed pigments are found in different plant extracts. Structures are suggested for 10 such condensed pigments detected in extracts of strawberry, runner beans, purple corn and grape skins, based on their MS" fragmentation patterns, following analyses by electrospray tandem mass spectrometry. All of them correspond to dimers containing a flavan-3-ol [either (epi)afzelechin, (epi)catechin or (epi)gallocatechin] as the upper unit carbon-carbon linked to a lower anthocyanin unit consisting of different delphinidin, cyanidin, pelargonidin, peonidin or malvidin derivatives. The detection of these pigments in plant extracts may suggest that they are natural pigments and not products exclusively formed during storage and ageing of processed foods and beverages, as was previously assumed.Comissão Europeia (Fundo Social Europeu) e Governo Português através do Programa PRODEP (III) - ref.ª 5.3/N/199.006/00-Doutoramento

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

Development of a fractionation method for the detection and identification of oak ellagitannins in red wines

[ES] During maturation and ageing in oak barrels wines improve their organoleptic properties. Ellagitannins can be released from wood to the wine and be involved in oxidation reactions and seem to influence the astringency and colour properties of the wine. Nevertheless, the ellagitannins levels are lower than those of other wine constituents and, consequently, they are not easily detected. This study has developed a two-step fractionation method consisting of a solid phase extraction in C-18 Sep-Pak® cartridges followed by size exclusion chromatography in hand-packed Sephadex LH-20 minicolumn for the detection of oak ellagitannins in different types of wines. An HPLC method has also been developed which allows the separation of compounds with the same m/z ratios, facilitating the ellagitannin identification by means of the mass spectrometric analyses. The main oak ellagitannins (grandinin, vescalagin, roburin E and castalagin) were isolated, detected separately and identified in a spiked wine and in three real ones, proving the usefulness of the fractionation method

Separation of pyranoanthocyanins from red wine by column chromatography

[EN] With the aim of monitoring the formation of anthocyanin-derived pigments and contributing to the study of their chromatic properties, stability and relative contribution to the colour of red wines, a method for fractionation of the colouring material was set up. The method was based on the distinct reactivity of the different pigment families towards bisulfite (hydrogen sulfite). The wine, acidified and bleached with NaHSO3, was placed in a Toyopearl® HW-40(s) gel column and submitted to elution with ethanol. Two fractions with different pigment compositions were collected and analysed by liquid chromatographay diode array detection-mass spectrometry. Compounds present in each fraction were identified according to their UV-visible and MSn mass spectra, showing that the first one was mostly constituted of pyranoanthocyanins, whereas the second basically contained anthocyanins and anthocyanin-flavanol condensation products. A large variety of new pigments were detected, some of which had not been previously reported in red wines, as far as we know. Characteristic MS2 and MS3 fragmentation patterns were observed within each family of compounds, which could be further applied for characterisation of unknown pigments in other wines

Study of phenolic markers for the differentiation of wines made with Vitis vinifera L. cv Rufete grapes.

The "D.O.P. Sierra de Salamanca" has been related, since its establishment, to the production of wines made with Vitis Vinifera L. cv Rufete grapes, an autochthonous grape from La Sierra de Francia. The production of this type of wine has been recently relaunched due to consumers' demand for new wines different from world standards and due to its potentially greater adaptation to an scenario of climate change. This study aims at establishing the phenolic composition of wines made with 100% Rufete grapes from the D.O.P Sierra de Salamanca, as well as establishing a comparison between the phenolic composition and the chromatic characteristics of these wines with commercial wines made with mixtures of Rufete and Tempranillo grapes in different proportions. The HPLC-DAD-MSn analysis of wine samples from three different wineries from the D.O.P allowed the identification of 35 different anthocyanin-derived pigments, 63 flavanols and 11 flavonols. From the phenolic composition and by means of principal component analysis (PCA), it has been possible to establish differences between the different wines depending on the vintage, the winery and the variety of grape.La Denominación de Origen Protegida (D.O.P.) Sierra de Salamanca siempre ha estado vinculada desde su fundación a la elaboración de vinos con uvas Vitis Vinifera L. variedad Rufete, una uva autóctona de la Sierra de Francia. Su producción en los últimos años se ha visto relanzada debido a la demanda por parte de los consumidores de nuevos vinos, diferentes a los estándares mundiales, y por su potencial de adaptación a un escenario de cambio climático. Con este estudio se pretende establecer la composición fenólica de vinos elaborados con uvas 100 % Rufete de la D.O.P Sierra de Salamanca, así como establecer una comparación de dicha composición fenólica y de las características cromáticas de los mismos con las de vinos comerciales elaborados con mezclas de uva variedad Rufete y variedad Tempranillo, en distintas proporciones. El análisis mediante HPLC-DAD-MSn de muestras de vinos procedentes de tres bodegas distintas de la D.O.P permitió identificar 35 pigmentos de naturaleza antociánica, 63 flavanoles y 11 flavonoles diferentes. A partir de la composición determinada y mediante análisis de componentes principales (PCA) se ha podido establecer diferencias entre las distintas muestras en función del año de producción, la bodega y la variedad de uva empleada

Color Stabilization of Red Wines. A Chemical and Colloidal Approach

Este artículo es parte del International Workshop on Anthocyanins (IWA2013)[EN]The effects of cold treatment and time on CIELAB color parameters and on anthocyanin and anthocyanin-derived pigments composition have been evaluated as has been the effectiveness of either an enological tannin or a mannoprotein (M) on their stabilization. With respect to color, hue (hab) was increased in the wines treated with both enological products. Furthermore, the color changes induced by cold treatment were lessened by the addition of these two enological products, although the protective effect was higher for the wines treated with M. The pigment analysis revealed higher percentages of anthocyanin-derived pigments in tannin and M-treated samples (in both cold treated and not) in relation to control ones. The addition of the enological tannin may favor the synthesis of anthocyanin-derived pigments, which are chemically more stable than native anthocyanins, whereas M seems to stabilize anthocyanin-derived pigments from a colloidal point of view, avoiding their aggregation and further precipitation

Diseño y simulación de un workshop sobre enología para la adquisición de conocimiento científico-técnico y mejora de las habilidades de comunicación en el alumnado

Memoria ID2023-098 Ayudas de la Universidad de Salamanca para la innovación docente, curso 2023-2024.[ES] El uso de metodologías donde los estudiantes adquieran una postura dinámica en su aprendizaje es clave para motivar al alumnado y fomentar su aprendizaje. En este contexto, emplear herramientas docentes que implican un aprendizaje mediante simulaciones en un contexto físico puede resultar de gran utilidad para la adquisición de competencias verbales y actitudinales que no se pueden trabajar de forma eficiente en las clases teóricas o en un contexto virtual durante la docencia. Con el fin de alcanzar una integración del conocimiento científico-técnico que se puede adquirir durante gran parte del Máster en Enología y su Adaptación al Cambio Climático (MUEACC) y, en concreto, en la asignatura, resulta de gran interés la aplicación de herramientas de simulación. En esa línea, la simulación de un workshop centrado en las propiedades organolépticas de los vinos, puede permitir al estudiantado enfrentarse a una situación real donde tenga que realizar una exposición de carácter científico-divulgativo mediante la presentación de una comunicación en formato póster, que estaría elaborado por ellos mismos. Este ejercicio obligará a aplicar los conocimientos y competencias trabajadas en la asignatura, colocando al alumnado en el centro de su propio proceso de enseñanza-aprendizaje. Además, permitirá fomentar la adquisición de conocimiento científico-técnico, la capacidad de síntesis y las habilidades de comunicación, así como el espíritu crítico, mediante la realización y aplicación de una rúbrica de evaluación