Macrowine 2021
IVES 9 IVES Conference Series 9 Impact of heating must before fermentation on Chardonnay wines

Impact of heating must before fermentation on Chardonnay wines


Prefermentation steps of white winemaking are very important for controlling the stability and the sensory attributes of wines. Usually musts are clarified by cold settling to prevent the start of the fermentation, before racking big lees and thus limiting the appearance of vegetable or reduction off flavour while favouring an aromatic expression with low turbidity. Besides, to reach the protein stability, some white wines further require a bentonite fining, sometimes associated with negative effects on the sensory quality. This study aims to know the impact of musts heating after pressing on a Chardonnay wine in northern conditions by comparison with a classic cold racking of the must. This technique appeared a few years ago to treat spoiled grape harvest or sub-maturity ones. After pressing and SO2 addition, a Chardonnay must was separated in two glass containers: one stored at 6°C during 12 hours and the other one heated at 65°C during 12 hours. A racking of the clear juice was then realized before temperature adjustment to 18°C for starting the alcoholic fermentation. All the other wine making stages, ageing and bottling were similar for both conditions. Without impact on the alcoholic fermentation, must heating gave a more expressive and aromatic wine with citrus fruits notes. The latter appeared early in the wine making process and remained after bottling, suggesting a likely higher concentration of volatile thiols. Two months after the bottling, the wine from the heated must was considered significantly fruitier, more persistent and was more appreciated in quantified descriptive analysis by a wine professionals panel. Must heating also led to chemical changes in the wine. Untargeted analysis by 3D fluorescence showed phenolic and protein component evolution for the heated must modality. Acid phenols and derivatives analysis showed that they were present in lower concentration in the heated must modality, contrary to caftarique or coutaric acids. Oxidation and esterification reactions with tartaric acid could have been favoured. Steric exclusion chromatography allowed to confirm hypotheses for the protein fraction. At the end of alcoholic fermentation, the high molecular weight fraction (> 200 kDa) seemed to decrease in the heated must modality. At the end of malolactic fermentation, fractions between 20 and 30 kDa, potientially associated with heat instable proteins, were also reduced in the heated must modality. A heat test realized after bottling confirmed that the heated must modality was stable, but not the control. This trial confirms the interest for this technique especially for cellars, which already have must heating equipments for red grapes (thermo process). This technique seems to favour the expression of fruity white wines. In a context of reduction of oenological waste production, a further advantage is that bentonite treatment seems to be no longer required.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster


Bertrand Chatelet*, Christian Coelho, Laurence Noret, Maria Nikolantonaki, Régis Gougeon, Valérie Lempereur


Contact the author


IVES Conference Series | Macrowine | Macrowine 2016


Related articles…

Phenolic profiles of minor red grape cultivars autochthonous from the Spanish region of La Mancha

The phenolic profiles of little known red grape cultivars, namely Garnacho, Moribel and Tinto Fragoso, which are autochthonous from the Spanish region of La Mancha (ca. 600,000 ha of vineyards) have been studied over the consecutive seasons of years 2013 and 2014. The study was separately performed over the skins, the pulp and the seeds, and comprised the following phenolic types: anthocyanins, flavonols, hydroxycinnamic acid derivatives (HCADs), total proanthocyanidins (PAs) and their structural features. The selected grape cultivars belong to the Vine Germplasm Bank created in this region in order to preserve the great diversity of genotypes grown in La Mancha.

How do different oak treatment affect the sensory composition of Chenin blanc wines over time?

Wooden barrels have been the preferred method for oak maturation for wines, but the use of alternative oak products, such as staves and oak chips have increased in South Africa due to lower production costs. This study investigated the effect of different oak products used during fermentation and ageing on the sensory profile, degree of liking and perceived quality of a South African Chenin blanc wine. The different wine treatments included an unoaked tank control wine, wines matured in 5th fill barrels, wines matured in new barrels from three different cooperages, and wines matured in 5th fill barrels with stave inserts from two different cooperages.

WineMetrics: A new approach to unveil the “wine-like aroma” chemical feature

“The Human being has an excellent ability to detect and discriminate odors but typically has great difficulty in identifying specific odorants”(1). Furthermore, “from a cognitive point of view the mechanism used to judge wines is closer to pattern recognition than descriptive analysis.” Therefore, when one wants to reveal the volatile “wine-like feature” pattern recognition techniques are required. Sensomics is one of the most recent “omics”, i.e. a holistic perspective of a complex system, which deals with the description of substances originated from microorganism metabolism that are “active” to human senses (2). Depicting the relevant volatile fraction in wines has been an ongoing task in recent decades to which several research groups have allocated important resources. The most common strategy has been the “target approach” in order to identify the “key odorants” for a given wine varietal.

An excessive leaf-fruit ratio reduces the yeast assimilable nitrogen in the must

Yeast assimilable nitrogen (YAN) in the grape must is a key variable for wine quality as a source of aroma precursors. In a situation of YAN deficiency, a foliar urea application upon the vine at veraison enhances YAN concentration and facilitates must fermentation. In 2013, Agroscope investigated the impact of leaf-fruit ratio on the nitrogen (N) assimilation and partitioning in grapevine Vitis vinifera cv. Chasselas following foliar-urea application with the aim of improving its efficiency on the YAN concentration.

Multivariate strategies for red wines classification using stilbenes and flavonols content

Bioactive polyphenols from grapes and wines, like stilbenes and flavonols (SaF), are often determined to nutritional evaluation, but also for many other purposes. The objective of this study was to quantify SaF in red wines from “Campanha Gaúcha”, a large and young viticultural region from South Brazil. Moreover, through statistical analysis, evaluate the influence of these compounds according to varieties, production process, harvest years and micro-regions of cultivation. A total of 58 samples of red wines were analyzed by high-performance liquid chromatography coupled to diode array detector (HPLC-DAD) for determination of trans-resveratrol (R), quercetin (Q), myricetin (M), kaempferol (K), trans-e-viniferin (V) and their precursor, cinnamic acid (C).