The influence of abiotic factors on the composition of berries, juice and wine in Vitis vinifera L. cv. Riesling

Media type: E-Book; Thesis

Title: The influence of abiotic factors on the composition of berries, juice and wine in Vitis vinifera L. cv. Riesling

Contributor: Brandt, Melanie [Author]; Stoll, Manfred [Degree supervisor]; Zorn, Holger [Degree supervisor]; Stoll, Manfred [Other]; Zorn, Holger [Other]; Winterhalter, Peter [Other]

Published: Geisenheim: Hochschule Geisenheim, 2021

Extent: 1 Online-Ressource

Language: English

Identifier:

Keywords: Hochschulschrift

Origination:

University thesis: Dissertation, Geisenheim, Hochschule Geisenheim, 2021

Footnote:

Description: Grapevine physiology and berry composition are highly influenced by abiotic factors, and this, in turn, affects wine composition and aroma. Primary metabolites, like sugars and acids, and also secondary metabolites, like phenols and terpenes, are sensitive to climatic conditions. However, the developmental stage of the berries and the environmental conditions within the bunch zone play a crucial role determining the different pathways of the metabolites and hence its concentration. This study aimed to investigate the influence of abiotic factors on the composition of berries, juice and wine of Vitis vinifera L. cv. Riesling. Field experiments were carried out in an experimental site of Hochschule Geisenheim University [Eibinger Magdalenenkreuz, Germany (49° 59'20'' N; 7° 55'56'' E)] using Riesling [clone 198–25Gm; grafted on rootstock SO4 Gm47 (Vitis berlandieri x V. riparia)]. In a non-irrigated vineyard, planted in 2007, the vines were trained to a vertical shoot position canopy system. The impact of global warming and rising temperature was one of the main questions of this thesis, and was simulated by an open heating system (OHS) in the vineyard. The tent-like construction passively heated the bunch zone. The effect of higher sun exposure on berries was trialed by the defoliation of the bunch zone at different stages of berry development. The removal of leaves around bunches is commonly used in coolclimate viticulture to improve the health status of berries and influence the aroma profile. Due to the increasing numbers of sunshine hours as well as the rising temperatures caused by climate change, the question then arises if in future defoliation practices will be the method of choice. Additionally, and in contrast, some bunches were placed in light-excluding boxes to simulate full shading. On days with high radiation, the open heating system clearly elevated temperatures compared to the control and the defoliation treatments. In the bunch zone above the open heating system, the air temperature was 4 °C higher compared to the other treatments. Inside the open heating system, the temperature was up to 13 °C higher. On days with low radiation, there was a minimal temperature difference between the treatments. The porosity of the bunch zone was quantified by a novel approach using lightsensitive films which provide a simple and accurate method for characterizing light conditions and quantifying cumulative radiation within the canopy. Different lightsensitive film qualities allow the measurement over a short period (3-7 days) or a more extended period (1-3 weeks). One of the significant advantages of this method will be that simultaneous measurement of several points will be possible. The health status of the berries was improved by defoliation and the infection (incidence and severity) of Botrytis cinerea reduced compared to the control providing a faster drying of bunches after morning dew or rainfall. Similarly, the OHS promoted airflow inside the bunch zone, causing same effects. Higher temperatures significantly reduced the berry weight, with the effect more pronounced if higher temperatures occurred before véraison. Berries grown under higher temperatures showed lower total soluble solids and the glucose to fructose ratio was impacted by lower glucose concentrations. A change in the glucose to fructose ratio will be of relevance for the fermentation since most yeasts prefer glucose over fructose. Defoliation treatment had no impact on the total soluble solids. In contrast, intense radiation or shading did not affect the berry size while extreme shading of the bunches reduced total soluble solids. Tartaric acid was not significantly influenced by higher temperatures or radiation, but malic acid concentrations strongly declined under warmer conditions. This decreased the total acidity in juice and wine, which is of particular importance for the wine profile of Riesling. The defoliation practices showed only little effect on the acid concentrations whilst the extreme shading treatments strongly increased the acidity. The analysis of phenols in berry skin was performed by high-performance liquid chromatography (HPLC) coupled to a photodiode array (PDA) detector and quantified with an external calibration. Flavonols, in particular, were influenced by higher sun exposure, with significantly higher flavonol concentrations found in the defoliation treatments. The time point when defoliation was applied had only small effects on the final total flavonol concentration. On the other hand, when a sunny period occurred after véraison flavanols revealed high concentrations after defoliation. Sunny periods before véraison or a ripening period with low sunshine hours did not increase the flavanol concentration compared to the control. No impact of the defoliation on the group of hydroxycinnamic acids, non-flavanoids, was The sensory assessment with small scale-vinifications was diverse. Only in the younger vintage, the panellists were able to detect differences in wines, which were mainly based on total acidity. The influence of the treatments to the grapes, which were observed for primary and secondary metabolites in berries and juice, were found in wine as well. The only expectation was TDN. In wines, higher TDN concentrations were always detected for the late defoliation. The early defoliation contained higher TDN concentrations if a sunny period occurred before véraison. Also, elevated temperatures caused higher TDN levels in wine. The prediction of the precise temperature and light conditions influencing TDN will require detailed investigations. A new approach was developed to analyse and quantify free and glycosidically bound monoterpenes and C13-norisoprenoids in berries, juice and wine. The sample volume was reduced by 90% and free analytes were directly analysed from the matrix with only little sample preparation. This simplified the analysis, saved time and made the use of organic solvents and solid-phase extraction cartridges redundant. The method was validated and compared to other methods in literature. In juice and wine 15 monoterpenes and four C13-norisoprenoids could be analysed simultaneously and the typically concentration ranges of the samples were covered. ; Weinreben und die Inhaltsstoffe der Trauben spiegeln den Einfluss abiotischer Faktoren wider und beeinflussen damit die Zusammensetzung des Weines und dessen Aroma. Die klimatischen Bedingungen beeinflussen Primärmetabolite wie Säuren und Zucker, aber auch Sekundärmetabolite wie Terpene und Phenole. Dabei hat die Intensität und der Zeitpunkt innerhalb der Beerenentwicklung einen entscheidenden Einfluss auf die Metaboliten selbst sowie deren Konzentration. Das Ziel dieser Studie war es, den Einfluss abiotischer Faktoren auf Inhaltsstoffe von Beeren, Traubensaft und Wein der Rebsorte Riesling zu untersuchen. Die Versuche wurden über drei Vegetationsperioden (2015 bis 2017) auf einer Rebfläche der Hochschule Geisenheim University [Eibinger Magdalenenkreuz, Deutschland (49° 59'20'' N; 7° 55'56'' E)] an der Rebsorte Riesling [Vitis vinifera L., Klon 198–25Gm; Unterlage SO4 Gm47 (Vitis berlandieri x V. riparia)] durchgeführt. Hierbei handelte es sich um eine nicht-bewässerte Rebfläche, die im Jahr 2007 gepflanzt und in einer Spaliererziehung bewirtschaftet wurde. Im Fokus stand die globale Erwärmung. Diese wurde durch einen kamin-ähnlichen Aufbau im Weinberg simuliert, welcher durch passive Erwärmung die Temperatur in der Traubenzone erhöhte. Des Weiteren wurden die Auswirkungen erhöhter Sonnenexposition auf die Trauben untersucht. Dafür wurde die Traubenzone zu unterschiedlichen Zeitpunkten in der Beerenentwicklung entblättert, was zu einer erhöhten Exposition der Trauben führte. Dies ist eine gängige Praxis im Weinbau, die zur Verbesserung der Traubengesundheit beiträgt, aber auch das Aromaprofil beeinflusst. Aufgrund der zunehmenden Sonnscheinstunden sowie die durch den Klimawandel steigenden Temperaturen, sind Entblätterungsintensität und –zeitpunkt gängiger Praktiken zu hinterfragen. Zur Veranschaulichung von gegenteiligen Extrembedingungen wurden Trauben durch Boxen geschützt. Damit wurde ein kompletter Lichtausschluss verursacht. Diese Variante ist zwar nicht praxisrelevant, zeigt jedoch als extremen Kontrast die Bedeutung von Licht für die Traubenentwicklung und diente in Teilen dazu, die Faktoren Licht und Temperatur getrennt voneinander zu betrachten. Der Kaminaufbau zeigte an Tagen mit einer hohen Sonnenstundenzahl eine deutliche Temperaturerhöhung in der Traubenzone. Im Vergleich zu den anderen Varianten wurden am oberen Rand der Traubenzone bis zu 4 °C wärmere Bedingungen aufgezeichnet. Am unteren Rand der Traubenzone, welcher innerhalb des Kamins lag, herrschten bis zu 13 °C höhere Temperaturen. Hingegen trat an strahlungsarmen, bedeckten Tagen kein Temperaturunterschied zwischen den Versuchsgliedern auf. Die Laubwandporosität der Experimente wurde durch ein...

Access State: Open Access

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