IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Determination of selected phenolics, carotenoids and norisoprenoids in Riesling grapes after treatment against sunburn damage

Determination of selected phenolics, carotenoids and norisoprenoids in Riesling grapes after treatment against sunburn damage

Abstract

Riesling represents the most widely cultivated grape variety in Germany and is therefore of particular economic interest. During recent years an increase in the petrol-note as well as in undesirable bitter and adstringent notes has been reported. These changes are most likely linked to increasing temperature and sunlight exposure of grapes due to climate changes.
The “petrol note” is caused by the formation of the C13-norisoprenoid 1,1,6-trimethyl-1,2-dihydronaphthalin (TDN), which originates from acid-labile precursors formed by the carotenoid degradation in the grape. The negative orosensory changes are thougt to be related to phenolic components in wine since some polyphenols have already been described as astringent and/or bitter. The grape responds to increased sunlight exposure by storing polyphenols, especially flavonoids, in the berry skin. The question whether viticultural treatments such as applications of particle-film forming products like kaolin and calcium carbonate preparations to reflect sun light and to mitigate sunburn damage on grapes and thus minimize organoleptic defects as well as off-flavors in resulting wines has not yet been sufficiently answered. 
In this study, we investigated the influence of defoliation at different degree in conjunction with the application of particle suspension to protect against sunburn damage in respect to selected carotenoids, C13-norisoprenoids and polyphenols in grapes. For comparability and possible correlation of results, qualitative and quantitative determination of C13-norisoprenoid and polyphenols was performed from the same sample extract. The carotenoid profile was analyzed by UHPLC-DAD and HPLC-APCI-MSn. Quantification was performed by UHPLC-DAD as lutein equivalents using an internal standard (β-apo-8-‘carotenal). Quantification of C13-norisoprenoids was conducted via SIVA with deuterated standards by HS-SPME-GC-MS/MS. The qualitative and quantitative analysis of polyphenols was done by HPLC-ESI-MSn and UHPLC-DAD by means of external calibration with representative substances for respective substance classes. The applied treatments showed effects on the qualitative and quantitative profiles of the analyzed constituents in grapes. While increased sunlight exposure induced the degradation of carotenoids, the mean content of C13-norisoprenoids and polyphenols increased.

DOI:

Publication date: June 27, 2022

Issue: IVAS 2022

Type: Poster

Authors

Maedge Inga1, Goek Recep1, Behne Sina1, Winterhalter Peter1, Waber Jonas2, Bogs Jochen2, Szmania Caterina2, Vestner Jochen2 and Fischer Ulrich2

1Institute of Food Chemistry, Technische Universität Braunschweig
2Dienstleistungszentrum Ländlicher Raum (DLR) Rheinpfalz, Institute for Viticulture and Oenology, Neustadt an der Weinstraße 67435, Germany

Contact the author

Keywords

Riesling grapes, sunlight exposure, carotenoids, norisoprenoids, phenolics

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Carry over effect of shoot trimming and deficit irrigation on fruit yield and berry total soluble solids

The increase in air temperature that is occurring in many important wine-growing areas around the world is resulting in the decoupling between the phenolic and the technological maturity of grapevine berries. This new ripening pattern leads to the production of light-bodied high alcoholic wines, but this is in countertendency with the increasing consumers’ demand for wines with low-to-mid alcohol concentrations. The oenological techniques proposed to reduce wine alcohol content are often very expensive and lead to detrimental effects on wine quality. Many viticultural practices have been proposed to slow down sugar accumulation the berry. One possible strategy that was previously found to be suitable for Aglianico grapevine is post-veraison shoot trimming. The aim of this work was to assess the carry over effects on the following year of shoot trimming and vine water status on yield and total soluble solids because the expected reduction in vine fertility could lead to a reduction in the effectiveness of shoot trimming.

Monitoring vineyard canopy structure by aerial and ground-based RGB and multispectral imagery analysis

Unmanned Aerial Vehicles (UAVs) are increasingly used to monitor canopy structure and vineyard performance. Compared with traditional remote sensing platforms (e.g. aircraft and satellite), UAVs offer a higher operational flexibility and can acquire ultra-high resolution images in formats such as true color red, green and blue (RGB) and multispectral. Using photogrammetry, 3D vineyard models and normalized difference vegetation index (NDVI) maps can be created from UAV images and used to study the structure and health of grapevine canopies. However, there is a lack of comparison between UAV-based images and ground-based measurements, such as leaf area index (LAI) and canopy porosity.

Effects Of Injections Of Large Amounts Of Air During Fermentation

Aim: Evaluating the effects of high amount of air injection during red wine fermentation process, on phenolic extraction dynamics, oxygen dissolution, phenolic compounds evolution, and oxidation of red wines.MethodsRed grapes musts were fermented in 100.000 L stainless steel tank, equipped with Parsec SRL “Air mixing” gas injection systems. For this experiment, treatments with two injection regimes, high and low intensity, and high and low daily frequency, were used. Oxygen analyzer was introduced into the tank to evaluate the gas concentration evolution along the fermentation.

Dormancy conundrum: thermal requirements plasticity to reach budburst may be explained by annual environmental dynamics

Deciphering grapevine dormancy is crucial in the current context of climatic challenges: advancing budburst phenology and increased late frost probabilities, observed in the last decades and expected to further increase, require deeper understanding. Beyond higher mean temperatures, abiotic stresses such as water deficit have also been emphasized as actors. In this framework, we aimed at exploring new methodologies for tracking dormancy cycle and testing the interplay on its regulation of temperature dynamics and drought.
In a first experiment, twenty-one Vitis vinifera varieties were monitored during ecodormancy and budburst over three years.

Entre ce que les consommateurs disent, ce qu’ils apprécient et ce qu’ils achètent… où se situent les vins de chasselas ?

Originaire du bassin lémanique, le chasselas est l’emblème de la viticulture suisse. Pour autant, les surfaces de chasselas n’ont cessé de diminuer, passant de 6’585 hectares en 1986 à près de 3’600 aujourd’hui, reflet d’une baisse de consommation. Une récente étude a cherché à comprendre les raisons de ce désintérêt. Réalisée dans