IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Hyperspectral imaging and Raman spectroscopy, nondestructive methods to assess wine grape composition

Hyperspectral imaging and Raman spectroscopy, nondestructive methods to assess wine grape composition

Abstract

Grape composition is of high interest for producing quality wines. For that, grape analyses are necessary, and they still require sample preparation, whether with classical analyses or with NIR analyses. The aim of the study was to test the ability of two nondestructive analyses, directly on grapes, hyperspectral imaging (HSI) and Raman spectroscopy to assess their composition.
For that, 7 grape varieties were analyzed for 2 vintages. Each grape was characterized by its technological ripening (levels of sugars, organic acids and pH) and its phenolic ripeness (total phenolic, total flavonoids, total anthocyanins contents, as well as extractable phenolic, extractable flavonoids, extractable anthocyanins, values obtained from a model wine maceration from skins, and color intensity). Spectra were recorded on 100 and 40 fresh berries per date and variety respectively with hyperspectral imaging and Raman. Raw data underwent different pretreatments (SNV, 1st and 2nd derivative) and PLS-R were then realized in order to provide models to assess grape composition.
The results showed that the 1st derivative data pretreatment generated better models and was then kept for all following analyses. Both methods, Raman spectroscopy and hyperspectral imaging, showed good ability to assess technological ripening parameters (sugar and acid contents) as well as phenolic content (TPI, Total Phenolics, Total Anthocyanins, Total Flavonoids and their extractable equivalents) (with globally R² > 0.81). However, it was not possible to reach the color intensity of grapes.
Even if both methods have the potential to assess wine grape quality on 11 important parameters, the quality of the models generated in our study was dependent on the quality parameter, the type of grapes (color) and the method, except for fructose, TSS and Extractable Anthocyanin contents, which were equivalent. Thus, the glucose concentration and the Total Phenolic Index (TPI) were better assessed by Raman spectroscopy, whereas Extractable Phenolics content was better estimated by HSI for both white and red grapes as well as Total  Anthocyanin content. Tartaric acid, Total Flavonoids, Color Intensity and extractable Flavonoids were better assessed by HSI for red grapes but by Raman for white grapes.
The quality of the generated models was yet dependent on the color of grapes and the parameter considered. More data would be necessary to strengthen the models but the proof of concept was successful with this study

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Maury Chantal¹, Gabrielli Mario², Ounaissi Daoud¹, Lançon-Verdier Vanessa¹, Julien Séverine¹and Le Meurlay Dominique ¹

¹USC 1422 GRAPPE, INRAE, Ecole Supérieure d’Agricultures, SFR 4207 QUASAV
²Dipartimento di Scienze e Tecnologie Alimentari per una filiera agro-alimentare Sostenibile, Università Cattolica del Sacro Cuore

Contact the author

Keywords

wine grape, hyperspectral imaging, Raman spectroscopy, phenolics, composition

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Impact of urbanization on optimum wine Terroirs in the Bordeaux region sample of one township of the Entre-Deux-Mers Area

L’étude présentée porte sur une commune de l’Entre-Deux-Mers dans le bordelais. Nous caractérisons dans un premier temps les potentialités des sols vis-à-vis de la production de vins rouges de qualité (délimitation de terroirs grâce à la prise en compte des couvertures pédologiques et des caractéristiques morphométriques du terrain : pentes, expositions, convexités. Dans un second temps, nous récapitulons l’évolution historique des occupations des sols depuis 1790 : l’emplacement des vignes est ainsi localisé sur les terroirs respectifs des communes. Enfin, une étude prospective résultant d’enquêtes sur l’utilisation du foncier, situe le devenir prévisible de l’espace étudié (en particulier dans ses composantes viticoles et urbaines).

Effect of terroir and winemaking protocol on the chemical and sensory profiles of Pinot Blanc wine

Wine research in the past years has mainly been focused on laboratory scale due to the possibility of controlling winemaking variables. Conversely, studies on wine quality in relation to the winemaking variables at the winery scale may be able to better account for the actual challenges encountered during wine production. Winemaking problems are recently arising from progressive changes in environmental conditions in relation to the terroir. It is important to realize that each wine region may have specific winemaking protocols and that winemakers often base their decisions on subjective, emotional, and empirical opinions. Due to all the above-mentioned issues, taking the correct decision in winemaking to achieve the desired goals may become even more challenging.

Ripening potential of Touriga Nacional variety with different canopy management techniques and in different regions (Dão, Bairrada and Vinhos Verdes)

Foreseeing climatic changes, the abnormally hot and dry year of 2005 can be revealer of some varieties behavior in different climatic conditions.

Agronomic and oenological characterization of the intraspecific cross ‘Passau’ in the aim of its commercial use

The study of new wine grape cultivars can be interesting to diversify the local wine productions without using international varieties. With this aim some Vitis vinifera intraspecific crosses obtained by Prof. Dalmasso in the 1930s and registered in the Italian National Catalogue in 1977, have been studied in the last years.

Talking about terroir

When talking about terroir, scientists and lay wine tasters, very much including wine journalists and wine growers, too often talk past one another.