III Reunión de Innovación Docente en Química, INDOQUIM 2008

La Reunión de innovación Docente en Química, INDOQUIM 2008, se celebra en esta ocasión en la ciudad de Cádiz del 23 al 25 de junio de 2008, estando organizada por profesores de la Facultad de Ciencias de la Universidad de Cádiz, y siendo su sede la Facultad de Filosofía y Letras de la UCA

Simplification of the DPPH assay for estimating the antioxidant activity of wine and wine by-products

The DPPH assay is one of the most commonly employed methods for measuring antioxidant activity. Even though this method is considered very simple and efficient, it does present various limitations which make it complicated to perform. The range of linearity between the DPPH inhibition percentage and sample concentration has been studied with a view to simplifying the method for characterising samples of wine origin. It has been concluded that all the samples are linear in a range of inhibition below 40%, which allows the analysis to be simplified. A new parameter more appropriate for the simplification, the EC20, has been proposed to express the assay results. Additionally, the reaction time was analysed with the object of avoiding the need for kinetic studies in the method. The simplifications considered offer a more functional method, without significant errors, which could be used for routine analysis

Use of Alternative Wood for the Ageing of Brandy de Jerez

The use of alternative types of wood has arisen for the aging of the Brandy de Jerez, on a pilot plant level. In particular, besides the use of American oak, two more types of oak have been studied, French oak and Spanish oak, allowed by the Technical File for the ID Brandy de Jerez, and chestnut, which, though it is not officially allowed, is a type of wood which had been traditionally used in the area for the aging of wines and distillates. All of them have been studied with different toasting levels: Intense toasting and medium toasting. The study of the total phenolic composition (TPI), chromatic characteristics, organic acids, and sensory analysis have proven that chestnut leads to distillates with a higher amount of phenolic compounds and coloring intensity than oak. This behavior is the opposite as regards the toasting of the wood. Among the different types of oak, Spanish oak produces aged distillates with a higher phenolic composition and a higher color intensity. Regarding tasting, the best-assessed samples were those aged with chestnut, French oak, and American oak, and the assessors preferred those who had used a medium toasting level to those with an intense leve

A Theoretical Approximation of the Accelerating Effects of Ultrasound about the Extraction of Phenolic Compounds from Wood by Wine Spirits

The acceleration on the extraction by the sonication of phenolic compounds (measured as the Total Phenolic Index) from wood chips by wine distillates is studied in the present paper. Using the Arrhenius equation, the theoretical temperature at which the kinetics obtained by these sonicated extraction processes are equal to the kinetics of non-sonicated and thermally accelerated extractions, was calculated. By applying a pseudo-second order kinetic model, it was shown that the initial rate values obtained from the sonicated extractions were as high as those obtained from the thermal extractions carried out at a temperature at least 2.5 degrees C higher than the real temperature at which the experiment was performed. Higher power densities lead to higher initial rates of extraction, although very high power densities decrease the amount of phenols in equilibrium, probably due to the degradation processes. Additionally, the positive synergy between the sonication and the movement of the recirculated distillate through wood chips was also stablished, obtaining a difference of temperature of at least,18.2 degrees C for the initial extraction rate and 7.0 degrees C for the equilibrium

Estudio de algunos compuestos de interés en preparados cosméticos realizados con residuos de vinificación del Jerez

Actas XI Congreso Nacional de Investigación EnológicaEl uso del vino en cosmética no es algo novedoso. Hay escritos que indican que ya desde la edad antigua se utilizaban mezclas preparadas con vino para el tratamiento de alteraciones de la piel. Lo que sí resulta una novedad es la posibilidad de utilizar los residuos de la vinificación con dicha finalidad. La uva y por consiguiente los residuos de la vinificación, presentan distintos compuestos de gran interés cosmético. Éste es el caso de los compuestos polifenólicos, que debido a su gran eficacia para atrapar radicales libres favorecen la integridad celular, pudiendo actuar como antioxidantes en fórmulas antienvejecimiento. De igual forma, algunos α-hidroxiácidos como el láctico, cítrico o tartárico, presentan importantes propiedades cosméticas debido a su efecto astringente. Estos compuestos al ser aplicados por vía tópica forman una fina capa protectora al reaccionar con las proteínas superficiales de la piel, generando una acción antitranspirante que a su vez produce un efecto hidratante y reafirmante. El objetivo de este trabajo ha sido determinar el contenido en diversos α-hidroxiácidos, así como el contenido polifenólico total y la actividad antioxidante en distintas muestras cosméticas que han sido elaboradas utilizando residuos de la vinificación de Vinos de Jerez

Determining the impact of seasoning on the volatile chemical composition of the oak wood of different Sherry Casks® by DTD–GC–MS

The casks that have contained for a certain time Sherry wines are known as Sherry Casks® and their use and value have increased in recent years, as they confer unique organoleptic properties to the distillates and beverages that are aged inside them. During their seasoning, these casks yield certain compounds from wood into the wines, and at the same time, they retain some compounds from these Sherry wines which, in turn, are transferred to the distillates that are aged inside the casks, so that wood acts as a transfer vector between the two alcoholic beverages. A characterization of seasoned staves with three Sherry wines, Fino, Oloroso, and Pedro Ximénez, by DTD–GC–MS has been carried out in this study. Different tendencies regarding the compounds present in the wood have been observed as follows: in general, certain compounds from wood either disappeared or decreased during its seasoning, while other compounds that come from the seasoning wine either increased or appeared in the wood during the seasoning process. This fact demonstrates that during the ageing of Sherry wines these transfer certain interesting compounds into the casks wood, which are in turn transferred to the distillates

Characterization of the Aromatic and Phenolic Profile of Five Different Wood Chips Used for Ageing Spirits and Wines

Wooden barrels and wood chips are usually used in the ageing of spirits and wines to improve their sensorial profile. Oak wood is the most popular material used in cooperage, but there are other interesting woods, such as cherry or chestnut, that could be considered for this purpose. In this study, a novel method for the determination of the aromatic profile of wood powder by Direct Thermal Desorption-Gas Chromatography-Mass Spectrometry (DTD-GC-MS) was optimized by experimental design. The volatile composition of five different types of wood chips was determined by direct analysis of wood powder by DTD-GC-MS method developed. Thirty-one compounds from wood were identified through this analysis, allowing the differentiation between woods. The aromatic and phenolic compound profile of the 50% hydroalcoholic extract of each type of wood studied was analyzed by Stir-bar Sorptive Extraction-Gas Chromatography-Mass Spectrometry (SBSE-GC-MS) and Ultra-High-Performance Liquid Chromatography (UHPLC) to determine which wood compounds are transferred to spirits and wine after ageing. Different phenolic profiles were found by UHPLC in each wood extract, allowing their differentiation. However, results obtained by SBSE-GC-MS did not allow distinguishing between wood extracts. The analysis of wood in solid state, without any type of previous treatment except grinding, by DTD-GC-MS does not imply any loss of information of the aromatic compounds present in wood as other techniques. This is a potential method to identify aromas in wood that, in addition, allows different types of wood to be differentiated

Influence of the type of Sherry wine and the length of time of the seasoning on phenolic and furanic compounds and CIEL*a*b* parameters of Brandies de Jerez

Brandy de Jerez is a unique spirit characterized by its aging in Sherry Casks®. Seasoning softens the casks’ wood and removes part of its extractable compounds, some of which are undesirable from an organoleptic point of view. The seasoning wine contributes with specific compounds that otherwise either would not be present at all in Brandies de Jerez, or they would in lower quantities. The length of time and the type of Sherry wine are two key parameters to be controlled when considering the seasoning process. In this study, a number of Brandies de Jerez have been aged in casks that were previously seasoned for 3, 6, 12, 18 or 60 months using either one out of three different Sherry wine types or a young fortified wine. It has been demonstrated that, according to the seasoning time and the type of wine used, significant variations with regard to phenolic and furanic compounds and CIEL*a*b* parameters would be detected between the brandies aged in the different casks

Study of the Cluster Thinning Grape as a Source of Phenolic Compounds and Evaluation of Its Antioxidant Potential

Thinning is a common viticulture practice in warm climates, and it is applied to increase the quality of the harvest. Thinning clusters are usually discarded, and they are considered another oenological industry waste. To valorize this by-product, the phenolic content and antioxidant activity of three red varieties (Tempranillo, Cabernet Sauvignon, and Syrah), thinned at three different times between veraison and harvest, were studied: the first at the beginning of the veraison stage, in a low ripening stage; the second in an intermediate ripening stage; and, finally, the third sampling in the highest ripening stage. These by-products showed high values of total phenolic contents (10.66-11.75 mg gallic acid equivalent/g), which is of the same order as or even higher than that found in grape pomace. In thinned grape were identified 24 phenolic compounds, being the flavan-3-ols (catechin and epicatechin) of particular interest, with mean contents ranging from 105.1 to 516.4 mg/kg of thinned grape. Antioxidant activity similar to that of the vintage grape was found. It is concluded that thinned grape is a good source of phenolic compounds. Its content does not depend mainly on the grape variety; however, it has been possible to establish differences based on the maturity stage of the thinning grapes: the intermediate ripeness stage, with a Brix degree in the range of 15-16 for this area, would be the optimum collection time for cluster thinning. In this intermediate ripeness stage, thinning grapes present a higher antioxidant activity and there is also appreciable anthocyanin content, which is not found for the lowest ripeness stage, since these samples present an intermediate composition in all the families of determined phenolic compounds: anthocyanins, flavonols, flavan-3-ols, cinnamic acids, and benzoic acids. It is important to note that the experiments in this study have been carried out with whole tinned grapes, without separating the skin or the seeds.This research was funded by Excellence Project of Consejeria de Innovacion, Ciencia y Empresa of the Junta de Andalucia (AGR6874)

Colour evolution kinetics study of spirits in their ageing process in wood casks

The colour of alcoholic beverages increases as they are aged in wood casks, due to the oxidation of the extracted phenols and tannic substances. In this paper, sixteen ageing experiments were carried out involving four different types of wood (American oak, French oak, Spanish oak and Chestnut), two toasting intensities (intense and medium toasting) and three initial wine distillates (holanda, wine spirit from a rectification column distillation and wine spirit from double distillation). Our experiments measured the CIEDE2000 colour difference as a control parameter for eight weeks. Four kinetic models were applied to better comprehend the evolution of the colour: Lagergren’s first-order model, Peleg’s pseudo-second-order model, an intra-particle diffusion model and a parabolic diffusion model. Differences on the non-linear correlation coefficients obtained by the Lagergren’s and the Peleg’s models show that the extractions are better fitted by the Peleg’s model, leading to deduce that the colour obtained in the ageing process of the spirit is a second-order kinetic procedure. Differences between both diffusion models show that colours obtained from holandas are more strongly affected by side-reactions than colours obtained from wine spirits, probably due to their higher content in non-alcoholic compounds. Peleg’s parameters show that toasting pre-treatments of wood also affect the kinetics of the colour obtained: intense toasted woods produce intense colours at the beginning of the ageing process, although medium toasted woods seem to produce more colour when equilibrium is reached