Olivier GEFFROY Associate professor in viticulture & enology [email protected] Rotundone in red wines An overview of the impact of plant material, environmental factors and viticultural techniques 4th Annual IVES - OENO One SCIENCE MEETING February 6, 2020 - Maison Hennessy, Cognac A few introductive words on wine aroma ➢More than 800 volatile compounds ➢About 10% of them have a sensory impact ➢Odorants belong to several chemical families Varietal thiol ➢Concentration levels from ng/L to hundreds of mg/L Ex. 3-sulfanylhexanol ➢If the varietal aroma of white wines is quite easy to apprehend (monoterpenols, varietal thiols…) ➢Those of red wine remained more mysterious or limited to undesirable molecule such as IBMP…. ➢Until the discovery of rotundone in 2008 ! Alkyl-méthoxypyrazines Ex. IBMP 2 Arôme poivré des vins rouges Interesting facts about rotundone (1/2) ➢Sesquiterpènes (C15H22O) = active compounds of essential oils ➢Found in Cyperus rotundus, pepper and aromatic plants ➢Odour threshold of 8 ng/L (water) and 16 ng/L (wine) ➢Heavy compound less volatile than monoterpenes ➢Produced by enzymatic oxydation of α-guaiene ➢20-25% of specific anosmia reported ➢Positively perceived except by young wine consumers ➢Particularly appreciated by wine connoisseurs who usually spent more than 10 euros for a bottle wine Wood et al. (2008), JAFC 3 Arôme poivré des vins rouges Interesting facts about rotundone (2/2) 96-99% 4-1% ➢96-99% of rotundone is located in the skin ➢Hydrophobic compound (≈10% extracted) ➢Strong affinity with particles ➢Winemaking practices have been identified to lower rotundone in wine (Saccharomyces uvarum, carbonic maceration)… ➢But not to enhance rotundone, including the increase in maceration temperature and the use of pectolytic enzyme ➢Effort to maximize rotundone in wine must be undertaken in vineyard ! Caputi et al. (2011), JAFC 4 Impact of genotypeArôme poivré des vins rouges Occurrence in wines frequently described as peppery (2008-2015) * Tardif (n=2) Manseng noir (n=2) Tannat (n=2) * >50 ng/L *Prunelard (n=1) *Négrette (n=1) * Malbec (n=1) * >16 ng/L * Fer (n=2) Duras (n = 15) South West of France * * Abouriou (n=1) *Pinot noir (n=1) *Pineau d'Aunis (n=3) *Mourvèdre (n=1) * Mondeuse (n=2) OtherFrance * Gamay (n=3) * Maturana tinta (n=1) Touriga nacional (n=1) Graciano (n=2) Foreign * * Arani (n=1) Geffroy (2018), Journée R&D Purpan 0 50 100 150 Geffroy (2018) 5 Impact of genotypeArôme poivré des vins rouges Occurrence in wines frequently described as peppery (2008-2015) * Tardif (n=2) Manseng noir (n=2) Tannat (n=2) * >50 ng/L *Prunelard (n=1) *Négrette (n=1) * Malbec (n=1) * >16 ng/L * Fer (n=2) Duras (n = 15) South West of France * * Abouriou (n=1) *Pinot noir (n=1) Merlot *Pineau d'Aunis (n=3) 19-62 ng/kg *Mourvèdre (n=1) * Mondeuse (n=2) Cabernet Franc OtherFrance * Gamay (n=3) 243 ng/kg * Maturana tinta (n=1) Touriga nacional (n=1) Cabernet Sauvignon Graciano (n=2) 21 ng/kg Foreign * * Arani (n=1) Geffroy (2018), Journée R&D Purpan 0 50 100 150 Takase et al. (2015), AJEV Geffroy (2018) Logan (2015), Doctoral Thesis 6 Impact of genotypeArôme poivré des vins rouges Occurrence in wines frequently described as peppery (2008-2015) * Tardif (n=2) Manseng noir (n=2) Tannat (n=2) * >50 ng/L *Prunelard (n=1) *Négrette (n=1) * Malbec (n=1) * >16 ng/L * Fer (n=2) Duras (n = 15) South West of France * * Abouriou (n=1) *Pinot noir (n=1) Up to 1345 ng/L *Pineau d'Aunis (n=3) in spirits (whisky, Mourvèdre (n=1) * tequila, rum) * Mondeuse (n=2) OtherFrance Gamay (n=3) * Concentrations * Maturana tinta (n=1) Touriga nacional (n=1) increase with barrel Graciano (n=2) aging time Foreign * * Arani (n=1) Geffroy (2018), Journée R&D Purpan 0 50 100 150 Genthner (2014), Master Thesis Geffroy (2018) 7 Impact of genotypeArôme poivré des vins rouges Clonal differences observed for Duras Geffroy et al. (2015a), JISVV ➢Clones 554 and 654 showed the greatest concentrations… ➢While clone 555 the lowest ➢In accordance with other works conducted on Shiraz (Siebert and Solomon 2011) and Grüner Veltliner (Caputi et al. 2011) ➢How to explain the extremely high levels for the 2014 vintage ? 8 Impact of biotic Arômefactors poivré des vins rouges Powdery mildew (Erysiphe necator) Geffroy et al. (2015a), JISVV 450 ➢Identification of a positive correlation between PM severity on bunches and 400 rotundone concentration 350 ➢Rotundone could be produced in 300 response to PM infection 250 ➢Systemic effect as wines were 200 produced from healty berries ? 150 Rotundone concentration (ng/L) concentration Rotundone 0 10 20 30 40 50 60 Powdery mildew severity (%) 9 Impact of biotic Arômefactors poivré des vins rouges Bunch rot (Botrytis cinerea) Geffroy et al. (2019a), OENO One ➢Negative correlation between rotundone 300 concentration and levels of gluconic acid 250 ➢Due to the fungus or to its laccase ? 200 ➢Rather unexpected as laccase has the ability to 150 convert α-guaiene into rotundone (Schilling et al., 2013) 100 ➢However, laccase can neutralize the toxic effect of 50 sesquiterpenes through oxydation (Mayer et Staples, Rotundone concentration (ng/L) concentration Rotundone 0 2002) 0 100 200 300 Gluconic acid (mg/L) 10 Impact of abioticArômefactors poivré des vins rouges Modeling rotundone in Duras wines PDO Gaillac ➢10 Duras blocks were monitored in 2013 and in 2014 ➢+ 50 variables were collected (fruit, vine, climate) and Ψstem was modelized ➢Rotundone was determined in wines made from microvinification techniques (1L Erlenmeyer flasks) ➢PLSR models were built to model rotundone in 2013, 2014 and in both vintages 11 Impact of abioticArômefactors poivré des vins rouges Modeling rotundone in Duras wines Geffroy et al. (2019a), OENO One 300 ➢Some blocks with high 2013 2014 250 rotundone levels in 2013 (i.e. n°2 and 4) exhibited low levels 200 in 2014 and conversely (i.e. n°3) 150 ➢Fixed variables (topography, plant material…) do not allow to 100 explain the differences between 50 blocks (ng/L) concentration Rotundone 0 1 2 3 4 5 6 7 8 9 10 Site number 12 Impact of abioticArômefactors poivré des vins rouges Modeling rotundone in Duras wines Geffroy et al. (2019a), OENO One ➢Positive contribution of cumulative rainfall, daily irradiation and hours of sunshine to the models ➢Negative contribution of the Huglin index ➢Water supply and light stimulate rotundone production while temperature has a depreciative effect ? 13 15 2011 14 a 2012 ab a Arôme poivré 13des vins rougesb How to manipulate rotundone12 concentration in wine ? c 11 Throught harvesting date 10 Degré Potentiel [% Vol] [% Potentiel Degré 9 Geffroy et al. (2014), AJGWR 70 ➢Kinetic of accumulation slightly 2011 60 differ between the two vintages 2012 a 50 a ➢In 2011, fast increase and then a reach a plateau 40 30 b ➢In 2012, steady increase Rotundone (ng/l) Rotundone 20 b ➢To enhance rotundone, dont pick 10 grapes too early ! 0 50% ver.+30 50% ver.+37 50% ver.+44 50% ver.+51 50% ver.+58 14 Arôme poivré des vins rouges How to manipulate rotundone concentration in wine ? Throught irrigation and defoliation Geffroy et al. (2014), AJGWR 70 ➢No impact of grape thinning 2011 +28% 60 a (40%) and jasmonic acid 2012 +28% ab 50 ab spraying on rotundone /l) b ng ( 40 ➢Positive effect of irrigation +39% +39% (4x10mm before veraison) 30 -69% 20 -69% Rotundone c -53% ➢Depreciative effect of -53% defoliation (2 faces at mid- 10 veraison) 0 Control Irrigation Jasmonic Defoliation Grape thinning acid 15 Arôme poivré des vins rouges How to manipulate rotundone concentration in wine ? Enhancing rotundone through irrigation while mitigating the depreciative impact on phenolics Geffroy et al. (2016), Scientia Horticulturae ➢While enhancing rotundone accumulation, irrigation is likely to have a depreciative impact on phenolic compounds (direct and indirect) ➢Can a cutting of the fruit bearing cane (PES) 20 days before harvest compensate this loss ? ➢We showed in 2013 and in 2014 that PES had a négligeable impact on rotundone accumulation ➢In 2014, implementation of a viticultural system combining irrigation (5x14mm) + PES 16 Arôme poivré des vins rouges How to manipulate rotundone concentration in wine ? Enhancing rotundone through irrigation while mitigating the depreciative impact on phenolics Parameter Control Irrigation + PES Δ / control Alcohol (% Vol.) 12.9 b 14.4 b +1.5 % vol. Total acidity (g/L tartaric acid) 5.59 b 6.51 a +0.92 g/L pH 3.60 a 3.61 a = Tartaric acid (g/L) 1.21 a 1.22 a = Volatile acidity (g/L acetic acid) 0.47 a 0.55 a = Anthocyanins (mg/L) 1061 b 1199 a +138 mg/L Total Phenol Index (TPI) 69.6 b 85.0 a +15.4 points Yield (kg/vine) 2.12 a 1.78 b -16% Rotundone (ng/L) 30 b 44 a +47% Geffroy et al. (2016), Scientia Horticulturae 17 70 A 60 Arôme poivré des vins rouges 50 How to manipulate rotundone concentration in40 wine ? 30 20 Throught differential harvest 10 r² = 0.76 rotundone concentration concentration rotundone rotundone (ng/L) (ng/L) 0 Geffroy et al. (2014), AJGWR -27.20 -27.00 -26.80 -26.60 -26.40 -26.20 -26.00 -25.80 δ13C ➢Correlation between 40 B rotundone and δ13C 35 30 ➢Rotundone is sensitive to weak 25 variation of water constraint 20 15 ➢Possibility to organize 10 differential harvest in order to 5 r² = 0.74 rotundone concentration (ng/L) concentration rotundone rotundone concentration (ng/L) concentration rotundone 0 produce wines with distinct -25.50 -25.00 -24.50 -24.00 -23.50 -23.00 -22.50 levels of peppery intensity ? δ13C 18 Arôme poivré des vins rouges How to manipulate rotundone concentration in wine ? Throught differential harvest Geffroy et al.