Macrowine 2021
IVES 9 IVES Conference Series 9 Response of different nitrogen supplementation on Saccharomyces cerevisiae metabolic response and wine aromatic profile

Response of different nitrogen supplementation on Saccharomyces cerevisiae metabolic response and wine aromatic profile

Abstract

The wine yeast Saccharomyces cerevisiae can highly affect wine aromatic profile by producing and/or mediating the release of a whole range of metabolites (such as thiols, esters, and terpenes), which in turn contribute to enhanced aroma and flavor. These metabolites depend on yeast metabolism activated during fermentation which can constitute the ‘’metabolic footprint’’ of the yeast strain that carried out the process. The aim of the present research was to study the metabolism of S. cerevisiae under two different nitrogen supplementation status and to investigate the relative expression of specific genes, that are directly related to the biosynthesis of specific potent odornats such as, terpenes and esters. 

The commercial yeast strains 1X (S.cerevisiae) and 2X (S.cerevisiae x S.bayanus) were inoculated in Moschofilero (Vitis Vinifera L. cv) grape must under two different concentrations of yeast assimilable nitrogen (YAN), a  low at 150 mg/L and a high at 300 mg/L. The produced wines were analyzed for their standard enological parameters, their volatile composition by SPE/GC–MS analysis as well as for their sensory profile. Totally 8 fermentations trials, were realised in triplicate. The fermentation was monitored by measuring the optical density and sugar consumption. Metabolic response was tested through real-time RT-PCR of genes implicated in aroma production of esters and terpenes such as ATF1, ATF2, EEB1, EHT1, IAH1, BGL2, EXG1. Sampling for metabolites and gene expression analysis were taken at the time of inoculation, after 48 hours, when two thirds of the sugars were depleted and at the end of the alcoholic fermentation (< 2g/L rs).

In terms of the volatile characterization of the wines, esters, linalool and nerol appeared to be clearly distinct between the different levels of YAN, which confirms the specialization in volatile compounds production among different nitrogen concentration levels. For instance, linalool was found to be at 0.05 mg/L for low nitrogen concentration, while high nitrogen levels resulted to a concentration of 0.12 mg/L. Real-time-PCR results revealed that, in both cases of nitrogen implementation, the analyzed genes were found to be expressed mainly before the fermentation of the 70% of the sugars. In addition, an overexpression of the BGL2 gene, corresponded well to the linalool concentration found, was observed in case of high nitrogen condition. Also, the EHT1 was expressed five times higher in case of high nitrogen concentration. Finally, correlations between ethyl esters and EEB1, acetate esters and ATF2 (p<0.05) were also found in both cases. 

Our study revealed the impact of different nitrogen implementations on the volatile compounds and the relative expression of specific genes. Metabolic analysis of selected volatile components of the wine aroma in conjunction with transcriptional analyses provide a great approach to orient the fermentation process towards a desirable wine aromatic profile.

DOI:

Publication date: September 3, 2021

Issue: Macrowine 2021

Type: Article

Authors

Despina Lola, Chrysanthi KALLONIATI, Maria DIMOPOULOU, Maria Ioanna XENIA, Emmanouil FLEMETAKIS, Yorgos KOTSERIDIS

Laboratory of Oenology and Alcoholic Drinks (LEAD), Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece, Laboratory of Molecular Biology, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece, Department of Wine, Vine and Beverage Sciences, School of Food Science, University of West Attica, Greece, Laboratory of Oenology and Alcoholic Drinks  (LEAD), Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece Laboratory of Molecular Biology, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece, Laboratory of Enology and Alcoholic Drinks (LEAD), Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece

Contact the author

Keywords

yeast metabolism, yan, nitrogen supplementation, volatile profile, gene expression

Citation

Related articles…

Underpinning terroir with data: rethinking the zoning paradigm

Agriculture, natural resource management and the production and sale of products such as wine are increasingly data-driven activities. Thus, the use of remote and proximal crop and soil sensors to aid management decisions is becoming commonplace and ‘Agtech’ is proliferating commercially; mapping, underpinned by geographical information systems and complex methods of spatial analysis, is widely used. Likewise, the chemical and sensory analysis of wines draws on multivariate statistics; the efficient winery intake of grapes, subsequent production of wines and their delivery to markets relies on logistics; whilst the sales and marketing of wines is increasingly driven by artificial intelligence linked to the recorded purchasing behaviour of consumers. In brief, there is data everywhere!

Opinions will vary on whether these developments are a good thing. Those concerned with the ‘mystique’ of wine, or the historical aspects of terroir and its preservation, may find them confronting. In contrast, they offer an opportunity to those interested in the biophysical elements of terroir, and efforts aimed at better understanding how these impact on vineyard performance and the sensory attributes of resultant wines. At the previous Terroir Congress, we demonstrated the potential of analytical methods used at the within-vineyard scale in the development of Precision Viticulture, in contributing to a quantitative understanding of regional terroir. For this conference, we take this approach forward with examples from contrasting locations in both the northern and southern hemispheres. We show how, by focussing on the vineyards within winegrowing regions, as opposed to all of the land within those regions, we might move towards a more robust terroir zoning than one derived from a mixture of history, thematic mapping, heuristics and the whims of marketers. Aside from providing improved understanding by underpinning terroir with data, such methods should also promote improved management of the entire wine value chain.

Upscaling the integrated terroir zoning through digital soil mapping: a case study in the Designation of Origin Campo de Borja

homogeneous zones by intersecting several partial zonings of major factors that influence vineyard growth. Each of them follows specific process from their corresponding disciplines. Soil zoning specifically refers to a Soil Resource Inventory map that has traditionally been generated by conventional soil mapping methods. These methods have shortcomings in reaching fine cartographic and categorical details and involve significant expenses, which undermines their applicability. A new framework named Digital Soil Mapping has introduced quantitative models by statistical techniques to establish soil-landscape relationships and is able to provide intensive scale cartography.

In the present study, a microzoning at 1:10.000 scale is generated from an initial zoning, where the conventional soil map with polytaxic map units is replaced by a new one from digital techniques that disaggregates them. The comparison between the zonings considers a quantitative evaluation of capability for each Homogeneous Terroir Unit by means of the Viticultural Quality Index and its categorization based on its distribution by map. The spatial intersection of both maps gives rise to a confusion matrix in which the flows of class variations after the substitution are assessed.

The results show a five-fold increase in the number of Homogeneous Terroir Units identified and a larger differentiation among them, evidenced by a wider range in the capability index distribution. Both elements are accompanied by an increase in the detection of areas of higher potential within previously undervalued uniform zones.These features are a direct effect of the improvements brought by Digital Soil Mapping techniques and would verify the advantages of their implementation in the Integrated Terroir zoning. Eventually, such new highly detailed terroir units would benefit precision viticulture and sustainable management practices.

Modeling the suitability of Pinot Noir in Oregon’s Willamette Valley in a changing climate

Air temperature is the key driver of grapevine phenology and a significant environmental factor impacting yield and quality for a winegrape growing region. In this study the optimal downscaled CMIP5 ensemble for computing thegrowing season average temperature (GST) viticulture climate classification index was determined to spatially compute on a decadal basis predictions of the GST climate index and the grapevine sugar ripeness (GSR) model for Pinot Noir throughout the Willamette Valley (WV) American Viticultural Area (AVA). Forecasts for average temperature and a 220 g/L target sugar concentration level were computed using daily Localized Constructed Analogs (LOCA) downscaled CMIP5 historic and Representative Concentration Pathways (RCP) future climate projections of minimum and maximum daily temperature. We explore spatiotemporal trends of the GST climate classification index and Pinot Noir specific applications of the GSR phenology model for the WV AVA. Spatiotemporal computations of the GST climate index and Pinot Noir specific applications of the GSR model enable the opportunity to explore relationships between their computed values with one intent being to provide updated GST ranges that better align with current temperature-based modeling understanding of Pinot Noir grapevine phenology and the viticultural application of LOCA CMIP5 climate projections for the WV AVA. The Pinot Noir specific applications of the GSR model or the GST index with updated bounds indicate that the percent of the WV AVA area suitable for Pinot Noir production is currently at or near its peak value in the upper 80s to lower 90s of this century.

A blueprint for managing vine physiological balance at different spatial and temporal scales in Champagne

In Champagne, the vine adaptation to different climatic and technical changes during these last 20 years can be seen through physiological balance disruptions. These disruptions emphasize the general grapevine decline. Since the 2000s, among other nitrogen stress indicators, the must nitrogen has been decreasing. The combination of restricted mineral fertilizers and herbicide use, the growing variability of spring rainfall, the increasing thermal stress as well as the soil type heterogeneity are only a few underlying factors that trigger loss of physiological balance in the vineyards. It is important to weigh and quantify the impact of these factors on the vine. In order to do so, the Comité Champagne uses two key-tools: networking and modelization. The use of quantitative and harmonized ecophysiological indicators is necessary, especially in large spatial scales such as the Champagne appellation. A working group with different professional structures of Champagne has been launched by the Comité Champagne in order to create a common ecophysiology protocol and thus monitor the vine physiology, yearly, around 100 plots, with various cultural practices and types of soil. The use of crop modelling to follow the vine physiological balance within different pedoclimatic conditions enables to understand the present balance but also predict the possible disruptions to come in future climatic scenarios. The physiological references created each year through the working group, benefit the calibration of the STICS model used in Champagne. In return, the model delivers ecophysiology indicators, on a daily scale and can be used on very different types of soils. This study will present the bottom-up method used to give accurate information on the impacts of soil, climate and cultural practices on vine physiology.

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.