Estudio del estado de madurez y la aptitud enológica en uva mediante análisis de imagen hiperespectral

La calidad del vino depende en gran medida de las características de la uva en el momento de la vendimia.Tradicionalmente el control de la variedad, el estado de maduración, la composición fenólica o la facilidad de cesión de estos compuestos al vino se ha realizado mediante métodos de análisis físico–químicos, que pueden resultar complejos y tediosos. Durante las últimas décadas ha comenzado el desarrollo detécnicas espectroscópicas que permiten estimar de forma rápida, no destructiva y respetuosa con el medio ambiente parámetros de interés agronómico. Entre estos métodos destacan los relacionados conla imagen hiperespectral, basados enla información espectral y espacial de la muestra. En el presente trabajo se ha utilizado el análisis de imagen hiperespectral en la región del infrarrojo cercano para la caracterizaciónde uvas y el desarrollo de diferentes metodologías que permitan evaluar su estado de maduración y aptitud enológica. Se ha comprobado la capacidad que el análisis de imagen hiperespectral en el infrarrojo cercano tiene para discriminar entre distintas variedades de uva consiguiendo resultados comparables con los obtenidos mediante lacaracterización química de las muestras.Así mismo, se han desarrollado modelos para la estimación de parámetros de interés enológico a partir de análisis de imagen hiperespectral con resultados satisfactorios. Han sido modelados parámetrosenológicos como la acidez total, el pH y la concentración de azúcares en el mostode uva,y la concentración de fenoles totales y de antocianos en el hollejo, los cuales tienen gran importancia en la vinificación. Además,la comparación con espectros reconstruidos mediante análisis de vectores característicosha demostrado que esta técnica permite reducir, en gran medida, la cantidad de información espectral necesaria para el desarrollo de modelos de calibración. Igualmente, se han propuesto modelos de predicción del contenido extraíble de antocianos, flavanoles y fenoles totales en hollejo de uva que permiten estimar de forma rápida la facilidad de cesión de estos compuestos desde las partes sólidas de la uva. Así mismo, utilizando espectroscopía en el infrarrojo medio por transformada de Fourier y espectroscopía Raman se han caracterizado espectralmente muestras de material no extraíble de hollejo y de semilla de uva (residuo sólido resultante tras la extracción de los compuestos fenólicos) y se han relacionado las características espectrales más importantes con la facilidad de extracción de compuestos fenólicos. De esta forma, se ha podido confirmar la relación existente entre la extractabilidad de compuestos fenólicos en hollejo y semilla de uva con la composición de su pared celular. Por último, se ha evaluado el efecto que tienela adición de extractos de semilla de uva blanca en la extracción de compuestos antociánicos del hollejo de uva tinta.La semilla de uva contiene copigmentos que mejoran las características colorimétricas del vino tinto, sin embargo, es posible que la presencia de estos copigmentos pueda alterar el equilibrio de extracción de los compuestos antociánicos del hollejo de uva. En el presente trabajo se ha comprobado que la adición de copigmentos provenientes de semillas de uva blanca no reduce la cantidad de antocianos extraídos en hollejo de uva durante la etapa de maceración.Wine quality mainly depends on the characteristics of harvested grapes. Traditionally, variety control, grape maturity, phenolic composition or phenolic compounds extractability are determined by physical and chemical analyses which are usually time consuming. During the past several decades, spectroscopic techniques have grown significantly as technology improved. This growth has allowed developing fast, non-destructive and green chemistry methods for the screening of different parameters of value for agriculture. Among them, hyperspectral imaging methods provide special and spectral information of the sample. In this work, near infrared hyperspectral imaging has been applied for the spectral characterisation of grapes. Afterwards, this spectral data has been used for the development of different methods for the evaluation of grape maturity and oenological capability. The ability of near infrared hyperspectral imaging for discriminating among different grape varieties has been checked. This technique shows similar results than traditional techniques, such as chromatographic analysis, for this purpose. Furthermore, hyperspectral imaging has been applied to grapes in order to develop different calibration models for the screening of several parameters linked to wine sector (i.e., sugar concentration, titratable acidity and pH of grape must, and total phenolic and anthocyanic compounds in grape skin). Moreover, characteristic vector analysis has been applied in order to reduce the amount of spectral data which is necessary for the calibration model development. In addition, calibration models have been developed for the screening ofextractable contentof anthocyanins, flavanols and total phenolic compounds ingrape skins. These models allow knowing how easily phenolic compounds are released from grape seed and skin to wine. In order to provide more information in this respect, Fourier transform infrared and Raman spectroscopy have been applied to grape seed and skin non–extracted material (solid residue obtained after exhaustive phenolic extraction). The main spectral features have been linked to phenolic extractability and it has been confirmed that grape seed and skin phenolic extractability is closely linked to the cell wall composition. Finally, the effect that copigments coming from white grape seeds has on the anthocyanin extraction from red grape skins has been evaluated. Grape seed contains copigments that can improve or stabilize wine colour, however, they might hamper the extraction equilibrium of anthocyanins compounds. In this work it has been proven that the addition of copigments coming from white grape seeds has not reduce the amount of extracted anthocyanins from red grape skin

Application of Problembased Learning to the Subject Photometry and Colour

En el presente capitulo se describe el ciclo de mejora en el aula (CIMA) desarrollado en la asignatura Fotometría y Color del Grado en Óptica y Optometría de la Universidad de Sevilla. En este CIMA se ha aplicado el Aprendizaje Basado en Problemas (ABP) para fomentar el trabajo centrado en el alumno en los seminarios de la asignatura. El CIMA ha tenido una buena acogida entre los alumnos y los resultados obtenidos son satisfactorios. Además, durante el desarrollo de esta mejora docente se han identificado varias características a mejorar en la actividad docente desarrollada y que serán tenidas en cuenta en el futuro.This chapter describes the classroom improvement cycle developed in the Fotometría y Color subject (degree in Optics and Optometry of the Universidad de Sevilla). The Problem-Based Learning (PBL) methodology has been applied in this cycle in order to promote the student-centre learning in the theoretical-practical section of the subject. This cycle has been well-accepted among the students and the obtained results are satisfactory. In addition, several characteristics to be improved in the teaching activity have been identified and will be considered in the future

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

Assessment of Total Fat and Fatty Acids in Walnuts Using Near-Infrared Hyperspectral Imaging

“Persian” walnut (Juglans Regia L.) is one of the most consumed tree nuts in the world. It is rich in several bioactive compounds, with polyunsaturated and monounsaturated fatty acids (PUFA and MUFA) appearing at high concentrations. Walnut consumption protects against cardiovascular, carcinogenic, and neurological disorders. The fatty acid profile has usually been determined by gas chromatography, a reliable and robust tool, but also complex, polluting, and time consuming. In this study, near infrared hyperspectral imaging has been used for the screening of total fat, MUFA, PUFA, saturated, and individual fatty acids in walnuts. Five different walnuts varieties have been considered and modified partial least square (MPLS) regressions have been performed. The SEs of prediction (SEP) in external validation (ranged from 2.12% for PUFA to 13.08% for MUFA) suggest that hyperspectral imaging can be a reliable tool for controlling these parameters in a simple, non-destructive and environmentally friendly way.FCT – Foundation for Science and Technology- ref:UIDB/05183/2020; FEDER and National Funds through the Programa Operacional Regional ALENTEJO 2020 (ALT20-03-0246- FEDER-000064) – QualFastNut – Utilização da espectroscopia NIR para a análise rápida da qualidade em frutos secos

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

Study of phenolic extractability in grape seeds by means of ATR-FTIR and Raman spectroscopy

Near infrared hyperspectral imaging has been applied to grape seeds in order to select a representative subset of samples according to their spectral features in the 900-1700nm range. Afterwards, selected grape seeds have been classified according to their total phenol and flavanol extractabilities. In this way, samples were sorted in three different groups identified as low, medium and high extractability levels. In order to establish the chemical structures which can be responsible for the different extractabilities, vibrational spectroscopy has been applied to the non-extracted material after seed extractions. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman spectra of non-extracted seed material have been recorded and their main spectral features have been linked to extractabilities of flavanolic and total phenolic compounds. The vibrational spectroscopic analysis confirms that grape seed phenolic extractability is influenced by the cell wall composition (polysaccharides, lignins, pectins) and by the degree of esterification of pectins

On the use of vibrational spectroscopy and scanning electron microscopy to study phenolic extractability of cooperage byproducts in wine

Wood is an important source of phenolic compounds, which can be transferred to wine during aging process, improving its properties, from an organoleptic point of view. Therefore, understanding and optimizing the extractability of phenolic compounds from wood are crucial in the oenological field. The structural composition of oak wood samples has been evaluated using Raman and attenuated total reflectance Fourier transform infrared (ATR–FTIR) spectroscopies, and their main spectral features have been linked to phenolic compound extractabilities, as measured by classic chemical analyses. To support the analysis, microscopic images of the samples were also recorded using scanning electron microscopy (SEM). The applied methodology is shown to be useful to relate the wood cell wall structure to phenolic extractability levels of wood samples. It could assist in selecting oak wood suited for improving wine quality with regard to its color or/and stability through the addiction of external copigments to wine

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

Response of mycorrhizal Touriga Nacional variety grapevines to high temperatures measured by calorespirometry and near-infrared spectroscopy

Heat stress negatively affects several physiological and biochemical processes in grapevine plants. In this work, two new methods, calorespirometry, which has been used to determine temperature adaptation in plants, and near-infrared (NIR) spectroscopy, which has been used to determine several grapevine-related traits and to discriminate among varieties, were tested to evaluate grapevine response to high temperatures. ‘Touriga Nacional’ variety grapevines, inoculated or not with Rhizoglomus irregulare or Funneliformis mosseae, were used in this study. Calorespirometric parameters and NIR spectra, as well as other parameters commonly used to assess heat injury in plants, were measured before and after high temperature exposure. Growth rate and substrate carbon conversion effciency, calculated from calorespirometric measurements, and stomatal conductance, were the most sensitive parameters for discriminating among high temperature responses of control and inoculated grapevines. The results revealed that, although this vine variety can adapt its physiology to temperatures up to 40 ºC, inoculation with R. irregulare could additionally help to sustain its growth, especially after heat shocks. Therefore, the combination of calorespirometry together with gas exchange measurements is a promising strategy for screening grapevine heat tolerance under controlled conditions and has high potential to be implemented in initial phases of plant breeding programsinfo:eu-repo/semantics/publishedVersio