Macrowine 2021
IVES 9 IVES Conference Series 9 Phenolic and volatile profiles of south tyrolean pinot blanc musts and young wines

Phenolic and volatile profiles of south tyrolean pinot blanc musts and young wines

Abstract

AIM. Assess the impact of different vineyards and winemaking variables on the phenolic and volatile profiles of Pinot Blanc musts and young wines from South Tyrol.

METHODS. Grapes were harvested during September 2019 in 3 vineyards near Ora (Italy) at 450 m (MM), 550 m (K) and 800 m (V) a.s.l. Six different types of Pinot Blanc musts and young wines were studied in 3 replicates. Study A – 3 different vineyards (MM_C, K_C, V_C), but same winemaking; Study B – same vineyard (V), but 3 different vinifications: i) grapes were frozen before crushing (V_F); ii) same as V_F, but co-inoculation yeast/malolactic bacteria (V_F_ML); iii) no grape freezing, but co-inoculation yeast/malolactic bacteria (V_ML). Phenolics were analysed by HPLC-DAD and HPLC-QqQ-MS, while volatiles were investigated by SPME-HS-GCxGC-ToF-MS. Standard oenological parameters were measured using a multi-parametric analyser, alcohol distillation, pH-meter and chemical titration. The data were statistically processed with ANOVA and Principal Component Analysis (PCA).

RESULTS. Upon a dataset of 27 phenolic compounds identified in musts, a good separation among samples was achieved using PCA. The musts produced without pre-fermentative grape freezing had significantly higher amounts of catechin, gallocatechin and astilbin. Besides, the musts from the same vineyard, but with frozen grapes showed higher concentrations of ethanol, glucose-fructose, malic acid, and lower concentration of tartaric acid. 46 phenolic compounds were identified in wines. The PCA separated well the samples of Study A: caftaric acid showed the most significant difference as well as the highest relative abundance. The PCA showed that the phenolic profile of the wines of Study B (V_C, V_F, V_F_ML, V_ML) clustered samples based on the pre-fermentative grape freezing. Wines made without frozen grapes were separated due to the higher phenolic concentrations. The volatile profile of wines after 1 month of storage contained 32 compounds. The PCA not only grouped samples according to the grape freezing, but it also showed that wines with no applied grape freezing were well clustered in terms of the presence/absence of malolactic fermentation in their winemaking. V_C samples were described by higher abundances of branched chain alcohols, while samples V_ML – by ethyl and phenylethyl esters.

CONCLUSIONS

The profiles of phenolics and volatiles were good discriminants of South Tyrolean Pinot Blanc wines produced under the same winemaking technology but harvested in different vineyards. In this study, the pre-fermentative grape freezing negatively affected concentrations of phenolics. The literature shows that freezing positively enhances contents only of anthocyanins and flavanol glucosides, while it negatively affects contents of phenolic acids and flavanols, that are main phenolic compound in white wines.

DOI:

Publication date: September 7, 2021

Issue: Macrowine 2021

Type: Article

Authors

Vakare Merkyte

1. Free University of Bozen-Bolzano, Faculty of Science and Technology, Piazza Università 5, 39100 Bozen-Bolzano, Italy; 2. Oenolab, NOI Techpark South Tyrol, Via A. Volta 13B, 39100 Bozen-Bolzano, Italy,Simone POGGESI, 1. Free University of Bozen-Bolzano, Faculty of Science and Technology, Piazza Università 5, 39100 Bozen-Bolzano, Italy; 2. Oenolab, NOI Techpark South Tyrol, Via A. Volta 13B, 39100 Bozen-Bolzano, Italy Edoardo LONGO, 1. Free University of Bozen-Bolzano, Faculty of Science and Technology, Piazza Università 5, 39100 Bozen-Bolzano, Italy; 2. Oenolab, NOI Techpark South Tyrol, Via A. Volta 13B, 39100 Bozen-Bolzano, Italy Fabian STENICO, 1. Free University of Bozen-Bolzano, Faculty of Science and Technology, Piazza Università 5, 39100 Bozen-Bolzano, Italy; 2. Oenolab, NOI Techpark South Tyrol, Via A. Volta 13B, 39100 Bozen-Bolzano, Italy Giulia WINDISCH, 1. Free University of Bozen-Bolzano, Faculty of Science and Technology, Piazza Università 5, 39100 Bozen-Bolzano, Italy; 2. Oenolab, NOI Techpark South Tyrol, Via A. Volta 13B, 39100 Bozen-Bolzano, Italy Emanuele BOSELLI, 1. Free University of Bozen-Bolzano, Faculty of Science and Technology, Piazza Università 5, 39100 Bozen-Bolzano, Italy; 2. Oenolab, NOI Techpark South Tyrol, Via A. Volta 13B, 39100 Bozen-Bolzano, Italy

Contact the author

Keywords

pinot blanc; white wine; phenolic profile; volatile profile; grape freezing; malolactic fermentation; chemical markers; vinification practices

Citation

Related articles…

Different soil types and relief influence the quality of Merlot grapes in a relatively small area in the Vipava Valley (Slovenia) in relation to the vine water status

Besides location and microclimatic conditions, soil plays an important role in the quality of grapes and wine. Soil properties influence…

Climate projections over France wine-growing region and its potential impact on phenology

Climate change represents a major challenge for the French wine industry. Climatic conditions in French vineyards have already changed and will continue to evolve. One of the notable effects on grapevine is the advancing growing season. The aim of this study is to characterise the evolution of agroclimatic indicators (Huglin index, number of hot days, mean temperature, cumulative rainfall and number of rainy days during the growing season) at French wine-growing regions scale between 1980 and 2019 using gridded data (8 km resolution, SAFRAN) and for the middle of the 21th century (2046-2065) with 21 GCMs statistically debiased and downscaled at 8 km. A set of three phenological models were used to simulate the budburst (BRIN, Smoothed-Utah), flowering, veraison and theoretical maturity (GFV and GSR) stages for two grape varieties (Chardonnay and Cabernet-Sauvignon) over the whole period studied. All the French wine-growing regions show an increase in both temperatures during the growing season and Huglin index. This increase is accompanied by an advance in the simulated flowering (+3 to +9 days), veraison (+6 to +13 days) and theoretical maturity (+6 to +16 days) stages, which are more noticeable in the north-eastern part of France. The climate projections unanimously show, for all the GCMs considered, a clear increase in the Huglin index (+662 to 771 °C.days compared to the 1980-1999 period) and in the number of hot days (+5.6 to 22.6 days) in all the wine regions studied. Regarding rainfall, the expected evolution remains very uncertain due to the heterogeneity of the climates simulated by the 21 models. Only 4 regions out of 21 have a significant decrease in the number of rainy days during the growing season. The two budburst models show a strong divergence in the evolution of this stage with an average difference of 18 days between the two models on all grapevine regions. The theoretical maturity is the most impacted stage with a potential advance between 40 and 23 days according to wine-growing regions.

Deconstructing the soil component of terroir: from controversy to consensus

Wine terroir describes the collectively recognized relation between a geographical area and the distinctive organoleptic characteristics of the wines produced in it. The overriding objective in terroir studies is therefore to provide scientific proof relating the properties of terroir components to wine quality and typicity. In scientific circles, the role of climate (macro-, meso- and micro-) on grape and wine characteristics is well documented and accepted as the most critical. Moreover, there has been increasing interest in recent years about new elements with possible importance in shaping wine terroir like berry/leaf/soil microbiology or even aromatic plants in proximity to the vineyard conferring flavors to the grapes. However, the actual effect of these factors is also dependent on complex interactions with plant material (variety/clone, rootstock, vine age) and with human factors.
The contribution of soil, although a fundamental component of terroir and extremely popular among wine enthusiasts, remains a much-debated issue among researchers. The role of geology is probably the one mostly associated by consumers with the notion of terroir with different parent rocks considered to give birth to different wine styles. However, the relationship between wine properties and the underlying parent material raises a lot of controversy especially regarding the actual existence of rock-derived flavors in the wine (e.g. minerality). As far as the actual soil properties are concerned, the effect of soil physical properties is generally regarded as the most significant (e.g sandy soils being associated with lighter wines while those on clay with colored and tannic ones) mostly through control of water availability which ultimately modifies berry ripening conditions either directly by triggering biosynthetic pathways, or indirectly by altering vigor and yield components. The role of soil chemistry seems to be weakly associated to wine sensory characteristic, although N, K, S and Ca, but also soil pH, are often considered important in the overall soil effect.
Recently, in the light of evidence provided by precision agriculture studies reporting a high variability of vineyard soils, the spatial scale should also be taken into consideration in the evaluation of the soil effects on wines. While it is accepted that soil effects become more significant than climate on a local level, it is not clear whether these micro-variations of vineyard soils are determining in the terroir effect. Moreover, as terroir is not a set of only natural factors, the magnitude of the contribution of human-related factors (irrigation, fertilization, soil management) to the soil effect still remains ambiguous. Lastly, a major shortcoming of the majority of works about soil effects on wine characteristics is the absence of connection with actual vine physiological processes since all soil effects on grape and wine chemistry and sensorial properties are ultimately mediated through vine responses.
This article attempts to breakdown the main soil attributes involved in the terroir effect to suggest an improved understanding about soil’s true contribution to wine sensory characteristics. It is proposed that soil parameters per se are not as significant determining factors in the terroir effect but rather their mutual interactions as well as with other natural and human factors included in the terroir concept. Consequently, similarly to bioclimatic indices, composite soil indices (i.e. soil depth, water holding capacity, fertility, temperature etc), incorporating multiple soil parameters, might provide a more accurate and quantifiable means to assess the relative weight of the soil component in the terroir effect.

Grape must quality and mesoclimatic variability in Fruška Gora wine-growing region, Serbia

The Fruška Gora mountain is a traditional wine-growing region in Serbia situated in the Pannonian Basin. Due to such a position, the vicinity of the Danube River and the presence of concave configuration, it is suitable for grape production. This paper provides analyses of spatial variations in meteorological parameters and grape juice quality within Fruška Gora wine region over three consecutive vintages (2018-2020). The examined period can be defined as warm with cool nights during September (AVG 18,9°C; GDD 1918°C; CI 12°CF) and with the presence of mesoclimatic variability. The East part of the study area was somewhat drier and hotter compared to other parts of the region. The analyses of grape must samples (190 in total) of five cultivars (Cabernet-Sauvignon, Merlot, Chardonnay, Sauvignon blanc and Grašac (Welschriesling)) commonly grown across the region (19 sites), were performed using Fourier Transform Infrared Technology (FTIR). Among all cultivars, Sauvignon blanc was harvested first in the East area (DOY=246±5, GDD at harvest=1552±74, 22.2±0.7 °Brix), while the latest harvest was recorded for Cabernet-Sauvignon in the West (DOY=283±5, GDD at harvest=1936±187, 23.4±1.0 °Brix ). Both the red and white cultivars had higher acidity and YAN in the grape must if the vines were grown in the North and East compared to South and West areas. According to PCA analysis, Grašac showed the lowest variation in grape must chemical composition. Thus, the results confirm that Grašac is the most stable cultivar in Fruška Gora. All monitored cultivars reached technological fruit ripeness by the end of the growing season. However, it was difficult to reach full ripeness of red cultivars, mostly beacuse of uncoupling of technolocical and phenolic ripeness. Thus, Cabernet-Sauvignon had higher variations in GDD sums at harvest compared to other cultivars, which probably increased variations in grape must quality.

A spatial explicit inventory of EU wine protected designation of origin to support decision making in a changing climate

Winemaking areas recognized as protected designations of origin (PDOs) shape important economic, environmental and cultural values that are tied to closely defined geographic locations. To preserve wine products and wine-growing practices adopted in different PDOs these areas are strictly regulated by legal specifications. However, quality viticulture is increasingly under pressure from climate change, which is altering the local conditions of many winegrowing areas. Therefore, maintaining traditional wine products will require the adoption of tailored adaptation strategies, including possible changes in the legal regulation of protected wines. To this end, it is necessary to have a comprehensive knowledge on PDOs including their extension, products and allowed practices. While there have been efforts to build databases that summarize the characteristics for individual wine PDO areas and to quantify the related effects of climate change, much information is still included only in the official documentation of the EU geographical indication register and has never been collected in a comprehensive manner. With this study we aim at filling this gap by building a spatial inventory of European wine PDOs that supports decision making in viticulture in the context of climate change. To map and characterize European wine PDOs, we analysed their legal documents and extracted relevant information useful for climate change adaptation. The output consists of a comprehensive geographical dataset that identifies the boundaries of all 1200 European wine PDOs at unprecedented spatial resolution and includes a set of legally binding regulations, such as authorized vine varieties, maximum yields and planting density. The inventory will allow researchers to analyse the impacts of climate change on European wine PDOs and support decision makers in developing tailored adaptation strategies. This includes, among others, the evaluation of new vineyard site selection, the expansion of cultivated varieties or the authorization of irrigation in vineyards.