terclim by ICS banner
IVES 9 IVES Conference Series 9 EFFECTS OF INDUCED SUNBURN DAMAGES ON WHITE WINE PROPERTIES

EFFECTS OF INDUCED SUNBURN DAMAGES ON WHITE WINE PROPERTIES

Abstract

Climate change is a great challenge for the environment and affects the wine industry as well. Sunburn damage of sensitive grapes increase with severe heat periods. Besides significant loss of yield sunburn, modifies sensory properties of the wines and may cause climate-related off-flavours. To initiate sun-burn in a controlled way, in 2021 sunburn was directly induced in the vineyard with the GrapeBurner device, exposing grapes of the varieties Riesling and Pinot Blanc with UV and IR radiation. This device was first assembled by Kai Müller of the university in Geisenheim and consists of a carriage with 6 UV/IR lamps. A 15 min irradiation was applied in early September at 60°Oe. Due to the colder season in 2021 the grapes were not harmed by previous sunburn damage. Nevertheless, we used non-defoliated grapes facing north of the vines to ensure that putative damage was only due to applied irradiation and not previous sun exposure. Three weeks after the treatment, a control and the irradiated grapes were harvested and directed to small scale winemaking following a standardised protocol. Sensory evaluation using descriptive analysis with a trained panel was complemented by aroma analysis using an established head space solid phase micro extraction GC-MS method.

For Riesling, the control had a sweeter and fruitier taste, and was reminiscent of ripe fruit, which correlated with a high content of ethyl esters. In contrast, wines from irradiated Riesling grapes had a smokier flavour and correlated with plant derived odorants such as vitispirane, linalool, β-damascenone, and 4-vinylguaiacol. Also the sensory panel described the wines from treated grapes as more astringent and bitter, as well as with a more intense yellow colour. These results were backed by Pinot Blanc trials, as the control was perceived more fruity due to enhanced ethyl esters. Vice versa, wines from the irradiated grapes were more smoky and astringent. In addition, 2-aminoacetophenone was enhanced, causing the atypical aging off-flavour.

These promising results stimulated further trials, in which the length of exposure was varied gradually, to determine a threshold from which irradiation is causing negative sensory and compositional changes. In parallel, mitigation strategies such as applying reflecting particles or adaptation to sun exposure by early defoliation will be examined in lieu of varying UV/IR radiation.

1. Droulia, F., Charalampopoulos, I. (2021). Future Climate Change Impacts on European Viticulture: A Review on Recent Scientific Advances. Atmosphere, 12(4), 495. https://doi.org/10.3390/atmos12040495
2. Gambetta, J. M., Holzapfel, B. P., Stoll, M., Friedel, M. (2021). Sunburn in Grapes: A Review. frontiers in Plant Science, 11, https://doi.org/10.3389/fpls.2020.604691
3. IPCC. (2014). Climate Change: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]Geneva, Switzerland. ISBN: 978-92-9169-143-2

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Poster

Authors

Caterina Szmania1, Ulrich Fischer1,2

1. DLR Rheinpfalz, Neustadt an der Weinstraße/Germany
2. RPTU Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern/Germany

Contact the author*

Keywords

climate change, sunburn, white wine, off-flavour

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

OPTIMIZATION OF EXTRACTION AND DEVELOPMENT OF AN LC-HRMS METHOD TO QUANTIFY GLUTATHIONE IN WHITE WINE LEES AND YEAST DERIVATIVES

Glutathione is a natural tripeptide composed of l-glutamate, l-cysteine and glycine, found in various foods and beverages. In particular, glutathione can be found in its reduced (GSH) or oxidized form (GSSG) in must, wine or yeasts¹. Numerous studies have highlighted the importance of GSH in wine quality and aging potential². During winemaking, especially during aging on lees, GSH helps prevent the harmful effects of oxidation on the aroma of the wine³. Nevertheless, the amounts of GSH/GSSG present in wine lees are often unknown and the choice of operating conditions (quantity of lees and aging time) remains empirical.

Read More

VOLTAMETRIC PROFILING OF RED WINE COMPOSITION DURING MACERATION: A STUDY ON FOUR GRAPE VARIETIES

During red wine vinification, maceration allows the must, and consequently the wine, to be enriched with several compounds that contribute to the creation of the typical organoleptic characteristics of red wines. Among these, extraction of polyphenols (PPs) during maceration is a major process of enological interest.
The purpose of this study was the evaluate the suitability of a rapid analytical approach based in linear sweep voltammetry to monitor PPs extraction during vinification.

Read More

MODULATION OF YEAST-DERIVED AROMA COMPOUNDS IN CHARDONNAY WINES USING ENCAPSULATED DIAMMONIUM PHOSPHATE TO CONTROL NUTRIENT RELEASE

Yeast-derived aroma compounds are the result of different and complex biochemical pathways that mainly occur during alcoholic fermentation. Many of them are related -but not limited- to the availability of nutrients in the fermentation medium and linked to nitrogen metabolism and biomass produced. Besides, the metabolic phase of yeast also regulates the expression of many enzymes involved in the formation of aroma active compounds. The work investigates the overall effect of continuous supplementation of nutrients during alcoholic fermentation of a grape must on the volatile composition of wines.

Read More

HAZE RISK ASSESSMENT OF MUSCAT MUSTS AND WINES : WHICH LABORATORY TEST ALLOWS A RELIABLE ESTIMATION OF THE HEATWAVE REALITY?

Wines made from Muscat d’Alexandria grapes exhibit a high haze risk. For this reason, they are systematically treated with bentonite, on the must and sometimes also on wine. In most oenological labora-tories and in companies (trade, cooperatives, independent winegrowers), the test that is by far the most widely used, on a worldwide scale, remains the heat test at 80°C for 30 minutes to 2 hours (and some-times up to 6 hours). The tannin test (sometimes coupled with a heat treatment) and the Bentotest are still used. In this study, we show that all these tests give much higher estimates of the haze risk than the risk assessed by a 24-48h treatment at 42°C, which represents a heat wave.

Read More

IMPACT OF MINERAL AND ORGANIC NITROGEN ADDITION ON ALCOHOLIC FERMENTATION WITH S. CEREVISIAE

During alcoholic fermentation, nitrogen is one of essential nutrient for yeast as it plays a key role in sugar transport and biosynthesis of and wine aromatic compounds (thiols, esters, higher alcohols). The main issue of a lack in yeast assimilable nitrogen (YAN) in winemaking is sluggish or stuck fermentations promoting the growth of alteration species and leads to economic losses. Currently, grape musts are often characterized by low YAN concentration and an increase of sugars concentration due to global warming, making alcoholic fermentations even more difficult. YAN depletion can be corrected by addition of inorganic (ammonia) or organic (yeast derivatives products) nitrogen during alcoholic fermentation.

Read More