Divulgación nutricional. Resolviendo dudas mediante debates

Memoria ID-0036. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2015-2016

Diseño y aplicación de una rúbrica para evaluar debates sobre divulgación nutricional

Memoria ID-0080. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2016-2017

Elaboración de vídeos tutoriales con Kaltura e integración en Studium. Fomentando el aprendizaje autónomo en asignaturas de Nutrición

Memoria ID2022-231 Ayudas de la Universidad de Salamanca para la innovación docente, curso 2022-2023

Caffeic and dihydrocaffeic acids promote longevity and increase stress resistance in caenorhabditis elegans by modulating expression of stress-related genes

[EN] Caffeic and dihydrocaffeic acid are relevant microbial catabolites, being described as products from the degradation of different phenolic compounds i.e., hydroxycinnamoyl derivatives, anthocyanins or flavonols. Furthermore, caffeic acid is found both in free and esterified forms in many fruits and in high concentrations in coffee. These phenolic acids may be responsible for a part of the bioactivity associated with the intake of phenolic compounds. With the aim of progressing in the knowledge of the health effects and mechanisms of action of dietary phenolics, the model nematode Caenorhabditis elegans has been used to evaluate the influence of caffeic and dihydrocaffeic acids on lifespan and the oxidative stress resistance. The involvement of different genes and transcription factors related to longevity and stress resistance in the response to these phenolic acids has also been explored. Caffeic acid (CA, 200 M) and dihydrocaffeic acid (DHCA, 300 M) induced an increase in the survival rate of C. elegans under thermal stress. Both compounds also increased the mean and maximum lifespan of the nematode, compared to untreated worms. In general, treatment with these acids led to a reduction in intracellular ROS concentrations, although not always significant. Results of gene expression studies conducted by RT-qPCR showed that the favorable effects of CA and DHCA on oxidative stress and longevity involve the activation of several genes related to insulin/IGF-1 pathway, such as daf-16, daf-18, hsf-1 and sod-3, as well as a sirtuin gene (sir-2.1)[ES] Los ácidos cafeico y dihidrocaféico son catabolitos microbianos relevantes, que se describen como productos de la degradación de diferentes compuestos fenólicos, es decir, derivados hidroxicinámicos antocianinas o flavonoles. Además, el ácido cafeico se encuentra tanto en forma libre como esterificada en muchas frutas y en altas concentraciones en el café. Estos ácidos fenólicos pueden ser responsables de una parte de la bioactividad asociada a la ingesta de compuestos fenólicos. Con el objetivo de avanzar en el conocimiento de los efectos sobre la salud y los mecanismos de acción de los fenoles de la dieta, el nematodo modelo Caenorhabditis elegans se ha utilizado para evaluar la influencia de los ácidos cafeico y dihidrocaféico en la vida útil y la resistencia al estrés oxidativo. La participación de diferentes genes y factores de transcripción relacionados con la longevidad y la resistencia al estrés en la respuesta a estos ácidos fenólicos también han sido explorados. El ácido cafeico (CA, 200 M) y el ácido dihidrocaféico (DHCA, 300 M) indujeron un aumento en la tasa de supervivencia de C. elegans bajo estrés térmico. Ambos compuestos también aumentaron la vida media y vida media y máxima del nematodo, en comparación con los gusanos no tratados. En general, el tratamiento con estos ácidos condujo a una reducción de las concentraciones intracelulares de ROS, aunque no siempre significativa. Resultados de los estudios de expresión génica realizados por RT-qPCR mostraron que los efectos favorables de CA y DHCA sobre el estrés oxidativo y la longevidad implican la activación de varios genes relacionados con la vía insulina/IGF-1 como daf-16, daf-18, hsf-1 y sod-3, así como un gen de sirtuina (sir-2.1

Elaboración de un protocolo de determinación de micronutrientes para su implamentación en la docencia práctica

Memoria ID-169. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2018-2019

Influence of Different Phenolic Copigments on the Color of Malvidin 3-Glucoside

[EN]The effectiveness of seven phenolic compounds (catechin, epicatechin, procyanidin B2, caffeic acid, p-coumaric acid, myricitrin, and quercitrin) as copigments of malvidin 3-glucoside, the major anthocyanin in red wines from Vitis vinifera, using a copigment/pigment molar ratio of 1:1 was assayed ) in model wine solutions under the same conditions (pH 3.6, 12% ethanol). The stability of the copigment- ° pigment complexes formed was studied during a storage period of 60 days at 25 °C. Tristimulus colorimetry was applied for color characterization of the copigmentation process, and HPLC-DAD- MS was used to monitor changes in the composition of the samples. Copigmentation has been found to occur in all cases despite the low copigment/pigment molar ratio used, although the effect was different depending on the compound. Flavan-3-ols appeared as the less effective copigments, procyanidin B2 being even worse than monomeric flavanols, whereas flavonols behaved as the best ones. These latter copigments also induced the most statistically significant bathochromic shift in ìmax. In the colorimetric analysis, it was observed that the lightness L* of the copigmented solutions increased with time, chroma C*ab decreased, and the hue hab increased. The copigments *ab ab that produced a greater increase in the hue angle were the monomeric flavan-3-ols, which therefore showed to be the least protective cofactors against browning of the anthocyanin solution during the storage. With the time of storage, the formation of new pigments was observed in the solutions containing flavanols (xanthylium structures) and hydroxycinnamic acids (pyranoanthocyanins), whic

Colour implications of self-association processes of wine anthocyanins

[EN] Copigmentation processes have been indicated to be crucial to stabilise coloured forms of the anthocyanins and explain colour expression in young red wines. Several studies exist about copigmentation between anthocyanins and different phenolics in model solutions, but little information is available about interactions among anthocyanins themselves. In this work, the process of self-association has been investigated in wine-like model solutions containing different grape anthocyanins (the 3-glucosides of malvidin, delphinidin and peonidin). The results obtained confirmed the existence of anthocyanin self-association and its influence on the apparent hydration constant of the anthocyanins with subsequent modification in the colour of the solutions. It was observed that the greater the degree of methoxylation of the anthocyanin B-ring the greater was the magnitude of the self-association. Colour analyses in the CIELAB space showed that self-association produces changes, which are more important in quantitative parameters (chroma, C ab* and lightness, L *) than in qualitative ones (hue, h ab). Self-association leads to an increase in C ab*, indicating a more intense colour of the solutions, and to a decrease in the psychometric index L *, meaning that a darkening is produced. The effects on the colour were more pronounced with the passage of time of storage of the solutions

Studies on the copigmentation between anthocyanins and flavan-3-ols and their influence in the colour expression of red wine

[ES] With the aim of evaluating the importance of the copigmentation process between anthocyanins and flavanols on the colour expression of red wine, assays were carried out in wine model systems with mixtures of compounds obtained from two Vitis vinifera grape varieties (Graciano and Tempranillo). Spectrophotometric and chromatic analyses were performed to evaluate the magnitude of the copigmentation and the modifications induced in the colour of the solutions. Measurement of the changes in the anthocyanin hydration constant (Kh) was also used to determine the strength of the copigmentation process. All the flavanols assayed induced significant changes in the colour, perceptible to the human eye, of the wine-like anthocyanin solutions at concentrations similar to those that can exist in red wines. The percentage contribution of the copigmentation with flavanols to the colour of the anthocyanin solutions was found to range from 2% to 20%. The extent of this effect was related not only to the concentration of flavanols but also to the qualitative composition of the flavanol preparations, as influenced by the part of the grape (either skin or seed) and the variety considered. Divergences were found between the evaluation of the copigmentation based on chromatic parameters in the CIELAB colour space and that based on the measurement at visible kmax, as the latter does not consider the integral colour changes produced in the visible spectrum. The results obtained confirmed the importance of the qualitative phenolic composition, determined in the wine by the type of grape and winemaking practices, to the production of an effective copigmentation process

Characterization of the Mean Degree of Polymerization of Proanthocyanidins in Red Wines Using Liquid Chromatography−Mass Spectrometry (LC-MS)

[EN] n HPLC-MS method for the characterization of proanthocyanidins (PA) has been refined. Further application to red wines provided interesting conclusions about the composition of the flavanol fraction and PA extractability during winemaking. The yield in PA extraction increases with the length of the postfermentative maceration (PFM), as well as the mean degree of polymerization (mDP) of wine flavanols. In early winemaking events mostly monomers to trimers are extracted from grape solids, whereas PFM is required for the significant extraction of higher oligomers. Nevertheless, at the end of a regular process of elaboration the mDP is not very high and does not usually exceed a value of 2.3, dimers and trimers being the predominant flavanols in red wines. With regard to groups of compounds, gallocatechins and prodelphinidins (located in the skins) are extracted rapidly in the first stages of the winemaking. On the contrary, long postfermentative macerations are required for the extraction of galloyled derivatives from the seeds. PA extractability is also dependent on the grape variety used for winemaking. Thus, wines made with Graciano grapes were found to require a longer process of PFM than those made from Tempranillo grapes to obtain similar yields in the extraction of flavanols

Evaluation of dihydroquercetin-3-O-glucoside from Malbec grapes as copigment of malvidin-3-O-glucoside

[EN] Malbec is a wine grape variety of great phenolic potential characterized for its high levels of anthocyanins and dihydroflavonols. To evaluate the possible implication of dihydroflavonols in the expression of red wine color through reactions of copigmentation or condensation, assays were carried out in wine model systems with different malvidin-3-O-glucoside:dihydroquercetin-3-O-glucoside molar ratios. The addition of increasing levels of dihydroquercetin-3-O-glucoside to a constant malvidin-3-O-glucoside concentration resulted in a hyperchromic effect associated with a darkening of the anthocyanin solutions, greater quantity of color and visual saturation, perceptible to the human eye. Copigmentation and thermodynamic measurements showed that dihydroquercetin-3-O-glucoside can act as an anthocyanin copigment, similar to other usual wine components like flavanols or phenolic acids, although apparently less efficient than flavonols. The high levels of dihydroflavonols existing in Malbec wines in relation to other non-anthocyanin phenolics should make this family of compounds particularly important to explain the color expression in Malbec young red wines