Tannin management: Use of Exogenous Tannins and Extended Maceration

Anita Oberholster Introduction

• Phenol composition of wine • Tannin structure and composition • Use of hydrolysable tannin • Use of condensed tannin • Addition of commercial tannin – During fermentation – After fermentation • Phenol extraction during fermentation – Extended maceration • Conclusion Most Important Grape Phenols

Benzoic acids Gallic acid

Non‐flavonoids

Cinnamic acids

Monomers Ex. catechin Phenols Flavan‐3‐ols Proanthocya‐ Oligomers nidins

Flavonoids Anthocyanin‐gluc Ex. Malv‐3‐gluc

Flavonols Most Important Grape Phenols • Flavonoids – Anthocyanins (red pigments) in skins

Anthocyanin Most Important Grape Phenols • Flavonoids – Flavan‐3‐ols in skins and seeds • (Epi)catechin, epigallocatechin, epicatechingallate • Oligomers and polymers of flavan‐3‐ols; proantho‐ cyanidins (PA) or condensed tannins (Fig. 1) • Seed PA (mDP ~ 12) • Skin PA (mDP ~ 30)

OH

Prieur et al. (1994) Phytochem. 36, 781‐784. Souquet et al. (1996) Phytochem. 43, (2), 509‐512. Flavan‐3‐ol Fig 1. Proanthocyanidins Most Important Grape Phenols • Flavonoids – Flavan‐3‐ols in skins and seeds • (Epi)catechin, epigallocatechin, epicatechingallate • Oligomers and polymers of flavan‐3‐ols; proantho‐ cyanidins (PA) or condensed tannins Fig 1 • Seed PA (mDP ~ 12) • Skin PA (mDP ~ 30) • Main contributors to astringency and bitterness OH

Prieur et al. (1994) Phytochem. 36, 781‐784. Souquet et al. (1996) Phytochem. 43, (2), 509‐512. Flavan‐3‐ol Hydrolysable Tannin • Classified as either gallo‐ or ellagitannins – Ellagitannins • Present in oak • Most important monomers are vescalagin, castalagin, less important are grandinin, roburin (Fig. 2) • More bitter then astringent, present in wine below detection limit, perhaps synergistic effect (Puech et al., 1999) – Gallotannins • Not been identified in oak wood • Present in nutgall, added to wine as commercial tannin

Puech et al. (1999) Am. J. Enol. Vitic. 50: 469‐478. Fig 2. Ellagitannins

Ribéreau‐Gayon et al., (2006) Handbook of Enology Hydrolysable Tannin

• Classified as either gallo‐ or ellagitannins – Ellagitannins • Present in oak • Most important monomers are vescalagin, castalagin, less important are grandinin, roburin (Fig. 2) • More bitter then astringent, present in wine below detection limit, perhaps synergistic effect (Puech et al., 1999) – Gallotannins • Not been identified in oak wood • Present in nutgall, added to wine as commercial tannin

Puech et al. (1999) Am. J. Enol. Vitic. 50: 469‐478. Organoleptic Effects of Tannin • Condensed tannins –bitter and astringent – Bitterness and astringency  with increase in polymerisation, but the ratio of bitterness to astringency  – Pigmentation decrease bitterness and increased and changed astringency attributes (Oberholster et al. , 2009) viscosity, fine emery, dry and grippy • Hydrolysable tannins –more bitter then astringent – Near or below detection limits in wine – Hydrolytic products are not astringent or bitter – May have synergistic effect with other wine phenolic compounds Oberholster et al. (2009) Austr. J. Grape Wine Res. 15: 59‐69. Wine tannin • Depends on grape composition • Extraction • Presence of wood or oenological (commercial/exogenous) tannin addition – ellagitannin and/or gallotannin • Main polymerization reactions – Oxidation reactions – Condensation with aldehydes (Fig. 3) – Direct reactions

Atanasova et al., (2002) Tetrahedron Lett. 43: 6151‐6153; Es‐Safi et al., (1999) J. Agric. Food Chem. 47:2096‐2102; Fulcrand et al., (1996) J. Chromatogr. 752:85‐91; Guyot et al., (1996) Phytochem. 42: 12789‐1288. Fig 3. Wine pigments

Flavanyl‐vinyl‐pyranoanthocyanin

Direct condensation

Mateus et al., (2003) J. Agric. Food Chem. 51: 1919‐1923; Reynolds (2010) Managing wine quality. Hydrolysable Tannin Content in Oak Aged Wines • [Ellagitannins] low in wine due to – Wood seasoning and toasting  ellagitannins – Chemical transformation in wine due to oxidation, polymerization and hydrolysis (8 ‐ 21 mg/L castalagin and 2 ‐ 7 mg/L vescalagin ) • Pyranoanthocyanins and other polymeric pigments with barrel maturation (Cano‐López et al., 2010; Del Ãlamo et al., 2010) – Malv‐3‐gluc and cat mediated reactions by oak‐ derived furfural, methyl‐furfural and vanillin – model solutions (Sousa et al., 2010 and Pissarra et al., 2004) Cano‐López et al., (2010) Food Chem. 119: 191‐195; Del Ãlamo et al., (2010) Anal. Chim. Acta 660:92‐101; Pissarra et al., (2004) Anal. Chim. Acta 513: 215‐221; Moutounet et al. (1989) Sci. Aliments. 9: 35‐41; Sousa et al. (2010) J. Agric. Food Chem. 58: 5664‐5669. Hydrolysable Tannin Content Influence on Polymeric Pigments • Saucier et al. (2006) also identified 5 ellagitannin derivatives in oak aged Bordeaux wine – Total 2 mg/L, catechin‐ and epicatechin‐ ellagitannin derivatives

Saucier et al. (2006) J. Agric. Food Chem. 54 (19): 7349‐7354. Commercial Tannins

• Commercial tannin extracted from nutgalls, tannin rich wood and grape seeds (Resolution Oeno, 2002) • Classification of commercial tannin – Condensed tannin (catechin > 50 mg/g or proanthocyanic tannin content > 0.5 mg/g) – Nutgalls (digallic acid content 4 –8 mg/g) – Oak (scopoletine content > 4 g/g) • Commercial tannin extracted with EtOH, water, ether or steam (Zoecklein, 2005; Saucier et al. 1997) Saucier et al. (1997) Phytochem. 46: 229‐234; Zoeklein et al. (1995) Wine analysis and production. Chapman & Hall. Use of Exogenous/Commercial Tannin • Tannin addition for following purposes or problem correction: – Contribute to mouthfeel/taste – Protect against oxidation enzymes, – Assist to precipitate proteins, – Modify aromas including vegetative aromas – Increase aging potential – Stabilize wine color • Few scientific publications about effect of commercial tannin addition Commercial Tannins added before Fermentation

Treatment and source Type of tannin according to Dosage (mg/L) the supplier

Tanenol Rouge (TR) Condensed & hydrolysable 100 300

Oenotan (Oeno) Hydrolysable 100 300

QCTN Hydrolysable 100 300

Tanin VR Supra (VR S) Condensed & hydrolysable 300 500 1000

Tanin VR Supra NF (VR hydrolysable 300 500 1000 NF)

Control (Cntrl) • Addition of different commercial tannins to wine (Merlot, Cabernet Sauvignon, Syrah) before fermentation (2004‐5)

• Small diffr in phenol comp end of fermentation, diminished over time Keulder, Oberholster, Du Toit (2006) Use of Commercial Tannin Pre‐ fermentation • Baurtistas‐Ortin (2005) tested 2 enological tannins on Monastrell wines – Gallo tannin (15 g/hL) and condensed tannin (40 g/hL) – Initial higher tannin conc and color – After 8 months lowest color, most brown – Condensed tannin still highest tannin and phenol conc – Neg aroma contribution, astringency, bitterness and dryness

Bautista‐Ortin et al., (2005) Int. J. Food Sci. Tech. 40: 867‐878. Commercial Tannin Additions Post‐ fermentation • Bowyer (2009) added VR Supra (300 mg/L) or oak chips (3 kg/tonne) during fermentation (Syrah) and compared with control (no additions) – Increase in total phenols: VR Supra  oak chips  control – Increase in color density: VR Supra  control  oak chips – Sensory evaluation after 12 months indicated that VR Supra wine was preferred • Parker et al. (2007) added 200 mg/L Oenotannin (GSeedEX) to Syrah, analysed until 2 years maturation – No signf diffr in wine color, pigment profiles or tannin – Sensory evaluation after 1 year showed no signf diffr Bowyer (2009) Austr. NZ Grapegr. Winemaker. 543: 61‐65; Parker et al. (2007) Austr. J. Grape Wine Res. 13: 30‐37. Commercial Tannin Additions Post Fermentation • Harbertson (2012) added tannin post fermentation to Merlot and Cab. Sauv. – Enological tannin (phenols) 12‐48% tannin using Adams‐ Harbertson assay – Merlot: added Tan’Cor 60 – 300 mg/L during barrel aging • Only signf tannin diffr at 300 mg/L • No sensory evaluation – Cab Sauv: Biotan (200, 800 mg/L); Gallacool (150 and 600 mg/L) • [Tannin] signf diffr for all • Tannin additions associated with neg sensory characteristics such as brown color, earthy and bitterness

Harbertson et al., (2012) Food Chem. 131: 999‐1008. Addition of Commercial Tannins to Wine Post Fermentation • Effect of different phenol content wines – Merlot and Cabernet Sauvignon (3 tannins, 100 mg/L) » pressed at 6°B or 10 days extended maceration – No signf diffr compared with respective controls – Addition of tannins did decrease diffr between wines made with and without extended maceration

• When O2 addition (0, 3 and 8 mg/L oxygen) were combined with tannin addition

– Clear that O2 had greater effect on phenol composition

Keulder, Oberholster, Du Toit (2006) Phenol Extraction

Extraction of malv‐3‐gluc during fermentation (Pinot noir)

Cortell et al., (2007) J. Agric. Food Chem. 55: 6585‐6595. Influence of Extended Maceration on Phenol Composition of Wine • Extended macerationcont… time • Increase in tannin, not anthocyanins • Total phenols increase up to 36 days • Anthocyanins reach maximum within 3 –5 days, although some studies have increases up to 10 days • Pomace contact of 4 –16 days were prefered by judges (this test was done on Merlot)

Gomez‐Plaza et al., (2001) Am. J. Enol. Vitic. 52: 266‐270. Mazza and Ford (2005) Austr. N.Z. Grapegr. Winemaker, 56‐61. Puertas et al., (2008) Food Sci. Tech. Int. 14 (Suppl. 5): 21‐27. Yokotsuka et al., (2000) J. Wine Res. 11: 7‐18. Zimman et al., (2002) Am. J. Enol. Vitic. 53: 93‐98. Concluding remarks • Tannin addition may have aroma and slight taste effect but generally do not increase color intensity or influence aging potential – It may have more important role in wine lacking phenol structure • Extended maceration do not increase color but do increase total phenol content – Proanthocyanidins extract continually • Optimal tannin to anthocyanin ratio for each wine