Estimation of Total Phenols, Flavanols and Extractability of Phenolic Compounds in Grape Seeds Using Vibrational Spectroscopy and Chemometric Tools

Near infrared hyperspectral data were collected for 200 Syrah and Tempranillo grape seed samples. Next, a sample selection was carried out and the phenolic content of these samples was determined. Then, quantitative (modified partial least square regressions) and qualitative (K-means and lineal discriminant analyses) chemometric tools were applied to obtain the best models for predicting the reference parameters. Quantitative models developed for the prediction of total phenolic and flavanolic contents have been successfully developed with standard errors of prediction (SEP) in external validation similar to those previously reported. For these parameters, SEPs were respectively, 11.23 mg g−1 of grape seed, expressed as gallic acid equivalents and 4.85 mg g−1 of grape seed, expressed as catechin equivalents. The application of these models to the whole sample set (selected and non-selected samples) has allowed knowing the distributions of total phenolic and flavanolic contents in this set. Moreover, a discriminant function has been calculated and applied to know the phenolic extractability level of the samples. On average, this discrimination function has allowed a 76.92% of samples correctly classified according their extractability level. In this way, the bases for the control of grape seeds phenolic state from their near infrared spectra have been stablished.España MINECO AGL2017-84793-C2España, Universidad de Sevilla VPPI-II.2, VPPI-II.

Valorization of American Barrel-Shoot Wastes: Effect of Post Fermentative Addition and Readdition on Phenolic Composition and Chromatic Quality of Syrah Red Wines

The influence of post fermentative addition of American barrel-shoot wastes on phenolic composition and chromatic quality of Syrah red wines has been evaluated as an environmentally sustainable alternative to the conventional winemaking for avoiding the common color loss of red wines elaborated in warm climates. American oak wood byproducts added were previously classified by hyperspectral image analysis according to the amount of phenolic compounds transferred to the extraction media. After that, wines were elaborated under different maceration conditions by applying only one proportion of wood (12 g L−1) and two different maceration procedures (simple and double addition) and were compared with a traditionally macerated Syrah red wine (CW, no wood addition). Results proved the effectiveness of the moderate postfermentative addition of oak wood byproducts to stabilize the color of wines and to provoke lower color modification along the time, producing color wines chromatically more stable for a better aging. In the case of double addition, the adsorption of the pigments during the maceration presents a stronger effect on the color than copigmentation and polymerization by cause of the copigments extracted from the woodEspaña, Ministerio de Economía y Competitividad AGL2017-84793-C

The color of wine - a historical-perspective .I. Spectral evaluations

In the 1930s trade transactions required that the color of wine be more rigidly specified. The wine‐colorimeter was useful with this purpose. Intensity of color was the first property to be considered. From the beginning of this century visual comparisons of wines with standard mixtures of dyes or colored substances (potassium permanganate and dichromate) were made. Later photometric studies (absorption curves) were developed. Maxima and minima in the absorption curve were defined, as well as their relationships. Recently, it has been shown that absorbance values at given wavelengths and luminosity are well correlated

The color of wine: a historical perspective. II. Trichromatic methods

The trichromatic theory was applied to wines at the end of the 1930s. Trichromatic co‐ordinates, dominant wavelength, purity and luminance were determined. The Munsell system and the Lovibond method, which had industrial applicability, were compared with the simplified methods proposed by the L'office Internationale de la Vigne et du Vin (OIV). These methods are official in Spanish food regulations on wine analysis. The CIE recommendations, through the weighted ordinate method, set up the colorimetric parameters for wines, such as hue, lightness, purity or saturation, differences of color, perceptibility. Lately, attempts have been made to correlate the chromatic properties of wines with composition, origin, aging and sensory evaluation. Some authors have studied the reliability of the OIV methods versus the more rigid recent CIE methods. Improved formulae for the computation of dominant wavelength and outstanding correlations among sensorial scores, chromatic parameters and anthocyanins (polyphenols) content of wines have been established

Aplicación de técnicas de imagen para la evaluación de la madurez fenólica de semillas de uva

Quality of wine depends fundamentally on the condition of the components of grapes at the moment of harvest. In this respect, their seeds directly affect to structure, astringency, stability, and indirectly to colour of wine. In this work, the grape seeds have been evaluated by techniques of image analysis. In all cases, the methodology was developed trying to entail the minimum sample preparation and maximum quickness of the method, and as far as possible, substitute the chemical analysis that usually involves long and tedious processes that hamper monitoring of ripening in a rapid way. The proposed methodology for measuring and evaluating colour and near infrared spectrum has yielded satisfactory results for estimating the ripening of grape seeds, and it has been useful for establishing stages of ripeness from their optical features.La calidad del vino depende en gran medida del estado en que se encuentren los diferentes componentes de la uva en el momento de la recolección y, en este sentido, las semillas afectan directamente a su astringencia, así como a la estructura y estabilidad del color del vino. En el presente trabajo se han evaluado semillas de uva de diferentes variedades aplicando distintas técnicas de análisis de imagen. En todos los casos se han desarrollado metodologías que implican la mínima preparación de muestra y la máxima rapidez del método, con el objeto de poder sustituir, en la medida de la posible, el análisis químico, que suele suponer largos y tediosos procesos que impiden un seguimiento rápido de la maduración. La metodología propuesta para la medición y evaluación del color y el espectro infrarrojo cercano ha dado resultados satisfactorios en la estimación del estado de madurez de las semillas de uva, y ha sido útil para establecer etapas de maduración a partir de sus propiedades ópticas.Ministerio de Economía y Competitividad AGL2008-05569-C02-02, AGL2011-30254-C02-02 y AGL2014-58486-C2-2-

Comparative study on the use of anthocyanin profile, color image analysis and near-infrared hyperspectral imaging as tools to discriminate between four autochthonous red grape cultivars from la Rioja (Spain)

Three independent methodologies were investigated to achieve the differentiation of red grapes from different grape varieties (Garnacha, Graciano, Mazuelo and Tempranillo) collected from five vineyards located in the D.O.Ca. Rioja. Anthocyanin chromatographic analysis, color image analysis and near infrared hyperspectral imaging were carried out for the grapes. Then, a Stepwise Linear Discriminant Analysis (SLDA) was developed for each data set in order to discriminate grapes according to their grape variety. As a result, using anthocyanin profile, color image analysis and near infrared hyperspectral imaging respectively, 88%, 54% and 100% of the samples were correctly classified in the internal validation process and 86%, 52% and 86% were correctly classified in the leave-one-out cross-validation proces

Development of an Emergency Radio Beacon for Small Unmanned Aerial Vehicles

Emergency locator transmitters (ELTs) used to locate manned aircrafts are not well suited to find and recover small crashed unmanned aerial vehicles (UAVs). ELTs utilize an international satellite system for search and rescue (Cospas-Sarsat System), which should leverage its expensive resources to save lives as a priority. Besides, ELTs are too big and heavy to be used within small UAVs. Some of the existing solutions for this problem are based on receivers that detect signal strength, which may be a long and tedious process not suitable for user needs. Others do not have enough range or require radio license and expensive amateur radio receivers. This paper presents an emergency radio beacon specifically designed to locate small UAVs. It is triggered automatically in the event of a crash and allows finding and recovering a crashed UAV in a fast and simple way. It meets not only the required specifications of user-friendliness, size and weight of this kind of application, but also it is a high precision and low cost device. Besides, it has enough range and endurance. The experiments carried out show the operation of the proposed system

Use of near infrared hyperspectral tools for the screening of extractable polyphenols in red grape skins

Hyperspectral images of intact grapes were recorded at harvest time using a near infrared hyperspectral imaging system (900–1700 nm). Spectral data have been correlated with red grape skin extractable poly- phenols (total phenolic, anthocyanins and flavanols) by modified partial least squares regression (MPLS) using a number of spectral pretreatments. The obtained results (coefficient of determination (RSQ) and standard error of prediction (SEP), respectively) for the developed models were: 0.82 and 0.92 mg g-1 of grape skin for extractable total phenolic content, 0.79 and 0.63 mg g-1 of grape skin for extractable anthocyanin content, 0.82 and 0.45 mg g-1 of grape skin for extractable flavanol content. The obtained results present a good potential for a fast and reasonably inexpensive screening of the extractable poly- phenolic compounds in intact grapes. Moreover, the heterogeneity of extractable polyphenols within the ripeness stage has been also evaluated using the proposed method

The color of olive oils: The pigments and their likely health benefits and visual and instrumental methods of analysis

The color of olive oils, and of foods in general, can influence consumer choices to a large extent and can be related to the processing treatments they have undergone. Olive oil color is due to 2 types of pigments, chlorophylls and carotenoids, which are attracting the attention of the scientific community due to the probable health benefits they can provide. Appropriate methodologies for the meaningful definition of the color of olive oil are there-fore necessary for various reasons. In this review, we discuss the importance of olive oil color and the applicable legislation and regulation, including sections devoted to the pigments accounting for the growing importance as likely health-promoting substances. Furthermore, we review in depth the different approaches (visual and instrumental methods) used for color measurements in the last 50 y. Instrumental methods have been shown to be highly appropriate for objective assessments and also for the rapid determination of the pigments

Método rápido de obtención de aceite de oliva virgen para determinación de acidez

A rapid and simple method to obtain, from olive samples, enough quantity of oil to determine acidity grade is proposed. From paste samples of milled olives, different fraction are separated to be centrifugated during 5 minutes at 4500 r.p.m. Oil acidity results obtained from sodium sulfate anhidrous and natural microtalc added samples are compared with blank samples, and with those obtained by the Abencor extraction procedure. The correlation between the acidity of oil samples obtained by the Abencor method is also analyzed against other samples obtained by the normalized method in Spain, norm UNE 55070, Soxhlet system. Results show that in all the centrifugated samples enough amount of oil is obtained to determin the acidity grade, it also show that treatment with sodium sulfate anhidrous obtains a bigger recovery percentage, and that in all 3 cases, the acidity shows a good correlation with that of the Abencor system, doubling the number of samples analysed by the Abencor system. It also shows that the acidity grade obtained by using the UNE 55070 norm is aproximately 0,3 grades above that obtained by the Abencor system.<br><br>Se propone un método rápido y sencillo para obtener, a partir de muestras de aceitunas, suficiente cantidad de aceite para determinar su grado de acidez. A partir de muestras de pasta de aceitunas molidas se separan distintas fracciones que se someten a un proceso de centrifugación a 4500 r.p.m. durante 5 minutos. Se comparan los resultados de acidez de los aceites obtenidos de las muestras con adición de microtalco natural y sulfato sódico anhidro, con muestras testigo, así como con el procedimiento de extracción Abencor. Se analiza también la correlación entre la acidez de muestras de aceite obtenidas por el método Abencor, con otras obtenidas por el método normalizado en España, norma UNE 55070, basado en la extracción del aceite por el método Soxhlet. Los resultados ponen de manifiesto que en las muestras centrifugadas se obtiene cantidad suficiente de aceite para la determinación del grado de acidez, que el tratamiento con sulfato sódico anhidro consigue mayor porcentaje de recuperación, y que, en los tres casos, la acidez presenta buena correlación con la del sistema Abencor, duplicando el número de muestras analizadas respecto a este método. Así mismo, se demuestra que el valor de acidez obtenido al aplicar la norma UNE 55070 es aproximadamente 0,3 grados por encima del obtenido por el sistema Abencor