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…

Making sense of available information for climate change adaptation and building resilience into wine production systems across the world

Effects of climate change on viticulture systems and winemaking processes are being felt across the world. The IPCC 6thAssessment Report concluded widespread and rapid changes have occurred, the scale of recent changes being unprecedented over many centuries to many thousands of years. These changes will continue under all emission scenarios considered, including increases in frequency and intensity of hot extremes, heatwaves, heavy precipitation and droughts. Wine companies need tools and models allowing to peer into the future and identify the moment for intervention and measures for mitigation and/or avoidance. Previously, we presented conceptual guidelines for a 5-stage framework for defining adaptation strategies for wine businesses. That framework allows for direct comparison of different solutions to mitigate perceived climate change risks. Recent global climatic evolution and multiple reports of severe events since then (smoke taint, heatwave and droughts, frost, hail and floods, rising sea levels) imply urgency in providing effective tools to tackle the multiple perceived risks. A coordinated drive towards a higher level of resilience is therefore required. Recent publications such as the Australian Wine Future Climate Atlas and results from projects such as H2020 MED-GOLD inform on expected climate change impacts to the wine sector, foreseeing the climate to expect at regional and vineyard scale in coming decades. We present examples of practical application of the Climate Change Adaptation Framework (CCAF) to impacts affecting wine production in two wine regions: Barossa (Australia) and Douro (Portugal). We demonstrate feasibility of the framework for climate adaptation from available data and tools to estimate historical climate-induced profitability loss, to project it in the future and to identify critical moments when disruptions may occur if timely measures are not implemented. Finally, we discuss adaptation measures and respective timeframes for successful mitigation of disruptive risk while enhancing resilience of wine systems.

Grape berry size is a key factor in determining New Zealand Pinot noir wine composition

Making high quality but affordable Pinot noir (PN) wine is challenging in most terroirs and New Zealand’s (NZ) situation is no exception. To increase the probability of making highly typical PN wines producers choose to grow grapes in cool climates on lower fertility soils while adopting labour intensive practices. Stringent yield targets and higher input costs necessarily mean that PN wine cost is high, and profitability lower, in line-priced varietal wine ranges. To understand the reasons why higher yielding vines are perceived to produce wines of lower quality we have undertaken an extensive study of PN in NZ. Since 2018, we established a network of twelve trial sites in three NZ regions to find individual vines that produced acceptable commercial yields (above 2.5kg per vine) and wines of composition comparable to “Icon” labels. Approximately 20% of 660 grape lots (N = 135) were selected from within a narrow juice Total Soluble Solids (TSS) range and made into single vine wines under controlled conditions. Principal Component Analysis of the vine, berry, juice and wine parameters from three vintages found grape berry mass to be most effective clustering variable. As berry mass category decreased there was a systematic increase in the probability of higher berry red colour and total phenolics with a parallel increase in wine phenolics, changed aroma fraction and decreased juice amino acids. The influence of berry size on wine composition would appear stronger than the individual effects of vintage, region, vineyard or vine yield. Our observations support the hypothesis that it is possible to produce PN wines that fall within an “Icon” benchmark composition range at yields above 2.5kg per vine provided that the Leaf Area:Fruit Weight ratio is above 12cm2 per g, mean berry mass is below 1.2g and juice TSS is above 22°Brix.

Exploring resilience and competitiveness of wine estates in Languedoc-Roussillon in the recent past: a multi-level perspective

The Languedoc-Roussillon wineries are facing a decline in wine yields particularly PGI yields due to many factors. Climate change is just ones, but is expected to increase in the future. There is also structurally a large heterogeneity of yield profiles among terroirs, varieties and strategies. This work investigates the link between yield, competitiveness and resilience to explore how resilient winegrowers have been in the recent past. To this end two approaches have been combined; (i) an accountancy database analysis at estate scale and (ii) municipality level competitiveness analysis. A new resilience indicator that characterizes the capacity of an estate to absorb yield variation is also defined. The FADN database between 2000 and 2018 of ex-Languedoc-Roussillon (France) and other data are used to analyse the current situation and the past evolution of competitiveness and resilience by type of estate (type of farm: PGI and/or PDO & type of commercialization: bulk and/or bottles). The net margin, which defines competitiveness, is not correlated to yield for all types but depends on the type of commercialization and the level of specialisation. The resilience indicator shows that the net margin of estates specialized in PGI is particularly sensitive to yield declines. We also show that price evolutions seem to compensate the effect of yield losses for the majority of types. Municipality scale analysis shows the links between local pedoclimate, yield, commercialization strategies and price. Overlapping a PDO with a PGI does not always increase a municipality’s PGI competitiveness. It is difficult to make links between causes and effects due to the complexity of the wine production system. Production diversification may be a solution. Resorting to the two level of analysis helps resolving the data gap that is necessary to explore the links between yield and economic performance of the wine estates in the long term.

20-Year-Old data set: scion x rootstock x climate, relationships. Effects on phenology and sugar dynamics

Global warming is one of the biggest environmental, social, and economic threats. In the Douro Valley, change to the climate are expected in the coming years, namely an increase in average temperature and a decrease in annual precipitation. Since vine cultivation is extremely vulnerable and influenced by the climate, these changes are likely to have negative effects on the production and quality of wine.
Adaptation is a major challenge facing the viticulture sector where the choice of plant material plays an important role, particularly the rootstock as it is a driver for adaptation with a wide range of effects, the most important being phylloxera, nematode and salt, tolerance to drought and a complex set of interactions in the grafted plant.
In an experimental vineyard, established in the Douro Region in 1997, with four randomized blocs, with five varieties, Touriga Nacional, Tinta Barroca, Touriga Franca and Tinta Roriz, grafted in four rootstocks, Rupestris du Lot, R110, 196-17C, R99 and 1103P, data was collected consecutively over 20 years (2001-2020). Phenological observations were made two to three times a week, following established criteria, to determine the average dates of budbreak, flowering and veraison. During maturation, weekly berry samples were taken to study the dynamics of sugar accumulation, amongst other parameters. Climate data was collected from a weather station located near the vineyard parcel, with data classified through several climatic indices.
The results achieved show a very low coefficient of variations in the average date of the phenophases and an important contribution from the rootstock in the dynamic of the phenology, allowing a delay in the cycle of up to10-12 days for the different combinations. The Principal Component Analysis performed, evaluating trends in the physical-chemical parameters, highlighted the effect of the climate and rootstock on fruit quality by grape varieties.

VINIoT: Precision viticulture service for SMEs based on IoT sensors network

The main innovation in the VINIoT service is the joint use of two technologies that are currently used separately: vineyard monitoring using multispectral imaging and deployed terrain sensors. One part of the system is based on the development of artificial intelligence algorithms that are feed on the images of the multispectral camera and IoT sensors, high-level information on water stress, grape ripening status and the presence of diseases. In order to obtain algorithms to determine the state of ripening of the grapes and avoid losing information due to the diversity of the grape berries, it was decided to work along the first year 2020 at berry scale in the laboratory, during the second year at the cluster scale and on the last year at plot scale. Different varieties of white and red grapes were used; in the case of Galicia we worked with the white grape variety Treixadura and the red variety Mencía. During the 2020 and 2021 campaigns, multispectral images were taken in the visible and infrared range of: 1) sets of 100 grapes classifying them by means of densimetric baths, 2) individual bunches. The images taken with the laboratory analysis of the ripening stage were correlated. Technological maturity, pH, probable degree, malic acid content, tartaric acid content and parameters for assessing phenolic maturity, IPT, anthocyanin content were determined. It has been calculated for each single image the mean value of each spectral band (only taking into account the pixels of interest) and a correlation study of these values with laboratory data has been carried out. These studies are still provisional and it will be necessary to continue with them, jointly with the training of the machine learning algorithms. Processed data will allow to determine the sensitivity of the multispectral images and select bands of interest in maturation.