Enhancing grapevine breeding efficiency through genomic prediction and selection index

Grapevine (Vitis vinifera) breeding reaches a critical point. New cultivars are released every year with resistance to powdery and downy mildews. However, the traditional process remains time-consuming, taking 20-25 years, and demands the evaluation of new traits to enhance grapevine adaptation to climate change. Until now, the selection process has relied on phenotypic data and a limited number of molecular markers for simple genetic traits such as resistance to pathogens, without a clearly defined ideotype, and was carried out on a large scale. To accelerate the breeding process and address these challenges, we investigated the use of genomic prediction, a methodology using molecular markers to predict genotypic values. In our study, we focused on 2 existing grapevine breeding programs: Rosé wine and Cognac production. In these programs, several families were created through crosses of emblematic and interspecific resistant varieties to powdery and downy mildews. Thirty traits were evaluated for each program, using 2 genomic prediction methods: Genomic Best Linear Unbiased Predictor and Least Absolute Shrinkage Selection Operator. The results revealed substantial variability in predictive abilities across traits, ranging from 0 to 0.9. These discrepancies could be attributed to factors such as trait heritability and trait characteristics. Moreover, we explored the potential of across-population genomic prediction by leveraging other grapevine populations as training sets. Integrating genomic prediction allowed us to identify superior individuals for each program, using multivariate selection index method. The ideotype for each breeding program was defined collaboratively with representatives from the wine-growing sector.

Charentaise distillation of cognac. Part II: Process simulation and impact of recycling practices on the aroma composition of freshly distilled spirit

A growing number of studies over the years has successfully employed computer simulation tools to understand, optimize and design spirit distillations. Amongst distilled spirits, cognac is a reputed wine spirit resulting from a double batch distillation process known as Charentaise distillation. This complex operation comprises the wine distillation (WD) and the brouillis distillation (BD), which are carried out in copper alembics. The distillate produced in each batch is fractionated and some of those fractions are recycled in subsequent batches. To improve the current understanding of the behavior of aroma compounds during the process, computer simulation modules were built in this work for a WD and a BD and the results were compared with experimental data. Of the 62 aroma compounds detected in the samples over time, 52 could be represented in the simulations, including 37 using the NRTL thermodynamic model to calculate vapor-liquid equilibria and another 15 with the UNIFAC model. Half of those had their concentration profiles and their partitioning accurately described by the simulation, most of which were modeled with NRTL. This highlights the need for reliable vapor-liquid equilibrium data for aroma compounds that were poorly represented or absent from the simulation as well as kinetic data for chemical reactions occurring during distillation. Furthermore, the impact of the recycling operation on the composition in aroma compounds of freshly distilled cognac was investigated. To represent a steady state, a mathematical model was employed to implement the recycling of distillate fractions during 8 successive Charentaise distillation cycles. The operation was shown to improve the extraction of ethanol and of all volatile compounds in the heart, reaching a pseudo steady state after 3 to 5 cycles. The recycling of the second fraction had a higher influence on the extraction of alcohols and terpenes, while for most esters and norisoprenoids the recycled head fractions played a bigger role.

Charentaise distillation of cognac. Part I: Behavior of aroma compounds

The Charentaise distillation plays an essential role in designing cognac aroma by extracting and selectively concentrating aroma compounds from the wine along with ethanol, in addition to promoting compound formation or degradation through different chemical reactions. This traditional mode of distillation still relies heavily on empirical knowledge and the impact of its different parameters on the composition of cognac is not fully elucidated. In this context, this study aimed to broaden the current knowledge on the behavior of aroma compounds throughout the two steps of the Charentaise distillation and to investigate the formation of aroma compounds during the operation, an aspect which is seldom considered. The concentration profiles of 62 aroma compounds were represented over time for a wine and a brouillis distillation in usual scale (25 hL) with recycling. A classification system was then proposed to group compounds based on their volatilities at different ethanol concentrations in the boiling liquid, their concentration profiles and their chemical properties. This could help identify how chemical characteristics of aroma compounds affect their volatilities in hydroalcoholic media during distillation. In addition, several compounds appear to be formed during distillation, most of which are terpenes, norisoprenoids and aldehydes. Finally, to highlight the importance of different compounds to the aroma of freshly distilled cognac, their odor activity values (OAV) in the heart fraction were estimated, revealing isobutanol and (E)-ß-damascenone to be the most odorant compounds. These results provided additional elements of understanding for different aspects of the Charentaise distillation for the production of cognac, several of which can be transposed, at least in part, to different modes of distillation pertaining to other distilled beverages.

The aromatic profile of wine distillates from Ugni blanc grape musts is influenced by the nitrogen nutrition (organic vs. inorganic) of Saccharomyces cerevisiae

Although the impact of nitrogen nutrition on the production of fermentative aromas in oenological fermentation is well known today, one may wonder whether the effects studied are the same when winemaking takes place at high turbidities, specifically for the production of wines intended for cognac distillation. To that effect, a fermentation robot was used to analyze 30 different fermentation conditions at two turbidity levels with several factors tested: (i) initial addition of nitrogen either organic (with a mixture of amino acids - MixAA) or inorganic with di-ammonium phosphate (DAP) at different concentrations, (ii) variation of the ratio of inorganic/organic nitrogen (MixAA and DAP) and (iii) addition of different single amino acids (alanine, arginine, aspartic acid and glutamic acid). A metabolomic analysis was carried out on all resulting wines to have a global vision of the impact of nitrogen on more than sixty aromatic molecules of various families. Then, at the end of the alcoholic fermentation, the wines were micro-distilled. A first interesting observation was that the aroma profiles of both wines and distillates were close, indicating that the concentration factor is rather similar for the different aromas studied. Secondly, the fermentation kinetics and aroma results have shown that the nitrogen concentration effect prevailed over the nature of nitrogen. Although the lipid concentration was in excess, an interaction between the assimilable nitrogen and lipid contents was still observed in wines or in micro-distillates. Alanine is involved in the synthesis of acetaldehyde, isobutanol, isoamyl alcohol and isoamyl acetate. Finally, it was demonstrated that modifying the ratio of assimilable nitrogen in musts is not an interesting technological response to improve the aromatic profile of wines and brandies. Indeed, unbalance the physiological ratio of the must by adding a single source of assimilable nitrogen (organic or inorganic) has been shown to deregulate the synthesis of most of the fermentation aromas produced by the yeast. Wine metabolomic analysis confirmed the results that had been observed in micro-distillates but also in the other aromatic families, especially on terpenes. The contribution of solid particles, but also yeast biosynthesis (via sterol management in must) to wine terpenes is discussed. Indeed, the synthesis of terpenes in this oenological context seems to be favored, especially since the concentration of assimilable nitrogen (in addition to the lipid content) favor their accumulation in the medium. A non-negligible vintage effect on the terpene profile was also demonstrated with variations in their distribution depending on the years. Thus, the present study focuses on the metabolism of wine yeasts under different environmental conditions (nitrogen and lipid content) and on the impact of distillation on the fate of flavor compounds. The results highlight once again the complexity of metabolic fluxes and of the impact of nitrogen source (nature and amount) and of lipids. Furthermore, this study demonstrates that beyond the varietal origin of terpenes, the part resulting from the de novo synthesis by the yeast during the fermentation cannot be neglected in the context of cognac winemaking with high levels of turbidity.

Sensorial Impact and Distribution of 3-Methyl-2,4-nonanedione in Cognacs and Spirits

The aim of this study was to improve our knowledge on the chemical markers of Cognac aromas. We report results concerning the distribution and sensorial impact of 3-methyl-2,4-nonanedione (MND), a well-known compound in aged red wine, reminiscent of anise or "dried fruit", according to its concentration. We assayed first this diketone (solid-phase microextraction (SPME)-gas chromatography (GC)/mass spectrometry (MS), chemical ionization (CI)) in many Cognac samples followed by grappa, brandy, rum, whisky, vodka, and fruit spirits, and concentrations ranged from traces to 11.2 μg/L. Highest concentrations were obtained in grappa and freshly distilled eaux-de-vie of Cognac samples. Exceeding its detection threshold (100 ng/L, 70 vol %), MND contributes to the anise descriptor of these spirits. Its concentration decreased over aging while being highly correlated with the total amount of fatty acid ethyl ester. In addition, we showed that MND was produced during distillation according to the oxidation state of the white wine as well as the amount of lees used.

Contribution of Volatile Odorous Terpenoid Compounds to Aged Cognac Spirits Aroma in a Context of Multicomponent Odor Mixtures

Cognac spirit aromas result from the presence of a wide variety of volatile odorous compounds associated with the modalities of spirit distillation and aging. However, very few studies have been carried out on aging notes of Cognac spirits. An HPLC fractionation approach was used in order to evidence fractions of interest recalling the specific aromatic nuances of aged Cognac. Then, a GC-O/MS analysis of the selected fractions allowed one to detect odorous zones and identify several volatile compounds. Among them, various well-known volatile compounds representative of the terpenoid family were highlighted, such as geraniol, α-terpinene, nerol, α-terpineol, 1,8-cineole (eucalyptol) and, particularly, piperitone, santalol, and α-campholenal, which have not previously been cited in Cognac. These compounds were quantitated and their detection thresholds were determined. Geraniol, α-terpinene, α-terpineol, and 1,8-cineole concentrations increased while spirits were more aged, while nerol tends to decrease. A sensory contribution of terpenes was observed through perceptual synergic effects, along with β-damascenone and whisky lactone.

The carbon neutrality principle: A case study in the French spirits sector

According to the 2019 Intergovernmental Panel on Climate Change (IPCC) report, putting in place policies that support sustainable development is imperative. The carbon neutrality concept introduced in 2002 is an efficient way to manage the risks and reduce the vulnerabilities in the land and the food system. Given the pivotal role of sustainability for todays' consumers, the low risk and high rewards of carbon neutral production could help businesses transform their entire sector. This article is among the first to show that the carbon neutrality principle offers advantages that far outweigh the costs of maintaining the status quo. The case study of a cognac producer in France suggests that prioritizing sustainable development by reducing emissions could be a beneficial solution, particularly in the high energy spirits industry. Specifically, implementing the three stages (and substages) of the carbon neutral methodology to calculate carbon footprint, this study provides evidence that distilling 1 hL of pure alcohol produces 0.9 tons of CO₂ emissions. Proposing actions to reduce emissions by 10%, and calculating the offset costs to evaluate the remaining emissions, the study also offers a practical implementation approach and discusses several potential legislative scenarios that might accelerate the transition to carbon neutral production output.

Quantification of megastigmatrienone, a potential contributor to tobacco aroma in spirits

A SPME-GC-MS method was adapted and validated in order to quantify 5 megastigmatrienones and related odorous compounds from oak wood: guaiacol, cis-whisky lactone, trans-whisky lactone, γ-nonalactone, eugenol, vanillin, and acetovanillone in a single run. The five megastigmatrienone isomers (tabanones) were quantified, for the first time, in Cognac, Armagnac and rum, as contributors to tobacco-like aromas. Spirits aged in oak barrels contain higher amounts, but megastigmatrienones are also present in freshly-distilled spirits. Statistical analysis revealed that freshly-distilled and barrel-aged spirits were differentiated by their megastigma-4,7E,9-trien-3-one levels. The Armagnac and Cognac samples were distinguished by their concentrations of the megastigma-4,6Z,8E-trien-3-one isomer.

Decoding the combinatorial aroma code of a commercial Cognac by application of the sensomics concept and first insights into differences from a German brandy

In the volatile fraction isolated from a commercial Cognac by means of extraction/SAFE distillation, 39 odor-active areas were detected, among which (E)-β-damascenone showed the highest flavor dilution (FD) factor of 2048 followed by 2- and 3-methylbutanol, (S)-2-methylbutanol, 1,1-diethoxyethane, ethyl methylpropanoate, and ethyl (S)-2-methylbutanoate, as well as 4-hydroxy-3-methoxybenzaldehyde (vanilla-like) and 2-phenylethanol. The quantitation of 37 odorants by stable isotope dilution assays and a calculation of odor activity values (OAV; ratio of concentration to odor threshold) resulted in 34 odorants with OAVs > 1. Among them (E)-β-damascenone, methylpropanal, ethyl (S)-2-methylbutanoate, ethyl methylpropanoate, and ethyl 3-methylbutanoate together with ethanol were established as key contributors to the Cognac aroma. Finally, the overall aroma of the Cognac could be mimicked by an aroma recombinate consisting of these 34 key odorants on the basis of their natural concentrations in the Cognac using an odorless matrix to simulate the influence of the nonvolatile constituents. A comparison of the FD factors of the key odorants identified in a German brandy to those in the Cognac suggested the pair (E)-β-damascenone and ethyl pentanoate as indicators to differentiate various Cognacs from German, French, and Spanish brandies. This was confirmed by calculating a ratio of the concentrations of (E)-β-damascenone to ethyl pentanoate for 12 Cognacs and 7 brandies from Germany and 2 from France and Spain, respectively.

Coulometric titration with electrogenerated oxidants as a tool for evaluation of cognac and brandy antioxidant properties

Stoichiometric coefficients for reactions of cognac antioxidants with coulometric titrants (electrogenerated bromine and hexacyanoferrate(III) ions) have been found. Ellagic and gallic acids react with both titrants while aldehydes (vanillin, syringic and coniferaldehyde) - with electrogenerated bromine only. Furfurals do not show significant reactivity toward both oxidants. Cognac and brandy total antioxidant capacity (TAC) and ferric reducing power (FRP) based on reactions with electrogenerated bromine and hexacyanoferrate(III) ions, respectively, have been evaluated. Both parameters for cognacs are statistically significant higher than for brandies and grow with the age increase. Beverages under investigation has shown relatively high antiradical activity toward 2,2-diphenyl-1-picrylhydrazyl (7-92% and 5-93% for cognacs and brandies, respectively). Total phenolics content has been evaluated by Folin-Ciocalteu method. Older beverages represent the higher phenolics content caused by more time of extraction from oak barrels. Positive correlations (r=0.8077-0.9617) have been observed for TAC and FRP with antiradical activity and total phenolics content.