The Australian Wine Research Institute
Strategies for reducing alcohol concentration in wine
Cristian Varela Senior Research Scientist
The Australian Wine Research Institute The Australian Wine Alcohol in Australian wine Research Institute
20142005
Average 13.6%14.5%
Ethanol
Godden et al. 2015 The Australian Wine Why is alcohol increasing? Research Institute
Grape maturity enhances rich, ripe fruit flavour, and colour intensity.
Decreases the unripe green and vegetal flavours.
Greater maturity leads to higher sugar content.
Higher sugar equals higher alcohol levels. The Australian Wine Why reduce alcohol? Research Institute
Too much!
15% 14% 13% 12% Ethanol content
Alcohol abuse Stuck
Sluggish Normal
Wine & society The Australian Wine How to reduce alcohol in wine? Research Institute
Varela et al. 2015
Viticultural practices Winemaking practices Fermentation practices Post-fermentation technologies The Australian Wine Viticultural practices Research Institute
Reducing leaf area Harvesting earlier
Decreasing LA/FM ratio uncouples sugar accumulation from other ripening changes
Several red varieties 0.6 % less ethanol, leaf removal Tempranillo reduction of 15% in TSS, theoretically 2% v/v less ethanol Sangiovese small reduction in TSS
Some have reported a decrease in anthocyanin concentration The Australian Wine Harvesting earlier: does alcohol matter? Research Institute
Observed changes in sensory profile during ripening Cabernet Sauvignon
Site/Season 1
Site/Season 2
Site/Season 3
Ripening
Fresh Green/ Red fruit/ Red Dark Over-ripe Vegetal Fresh Green fruit fruit Fruit
Alcohol concentration from: 11.8 % v/v to 15.5 % v/v The Australian Wine Wines harvested earlier Research Institute
Bindon et al. 2013
Low esters Low anthocyanin Low glycerol and alcohol High methoxypyrazine and C6 compounds
Low extractable tannin, seed tannin > skin Low tannin polymerisation
High grape-derived polysaccharides The Australian Wine Wines harvested later Research Institute
Bindon et al. 2013
High esters
High anthocyanin
High glycerol and alcohol
Low methoxypyrazine and C6 compounds
High extractable tannin, higher mDP, skin > seed
Low grape-derived polysaccharides
High mannoproteins The Australian Wine Some sensory data – palate attributes Research Institute
5.00 Bindon et al. 2014
4.50
4.00
3.50
3.00
2.50
Mean Score Mean 2.00
1.50
1.00 H1 H2 0.50 H3 H4 H5 0.00 Overall fruit*** Dark fruit* Red fruit*** Hotness*** Fresh Green* Fruit Aftertaste*** The Australian Wine Consumer liking Research Institute
Bindon et al. 2014 Alcohol Consumer preference 15.5 16.0 7.0 a ab ab b 13.6 14.0 6.0 c 11.8 12.0 5.0
10.0 score Liking 4.0
Concentration [%v/v]Concentration 8.0 3.0 H1 H2 H3 H4 H5 H1 H2 H3 H4 H5 Harvest Harvest
Harvesting earlier could deliver a wine that consumers prefer or like just as much and contains up to 2 %(v/v) less alcohol
Caution: One trial – one variety – one vintage The Australian Wine Winemaking practices Research Institute
Blending Fermentation design Choice of yeast strain Verdelho and Petit Verdot harvested at two maturities for each variety wines differed 3% v/v mixed in equal volumes final wine 1.5 % v/v less alcohol similar sensory composition than ‘mature’ wines
Longo et al. 2017a The Australian Wine Choice of wine yeast Research Institute
Palacios et al. 2007
Not much variation in ethanol yields for commercial wine yeast strains The Australian Wine Low-ethanol wine yeasts Research Institute
Genetically modified (GM) strains
S. cerevisiae
Generation of new strains (nonGM) mutagenesis, adaptive evolution
Isolation and characterisation of strains
Non-Saccharomyces The Australian Wine Non-GM techniques Research Institute
Mutagenesis Adaptive evolution
Selective pressure that drives alcohol down
Mutant yeast
Low alcohol yeast
Screening of Wine yeast low alcohol phenotype The Australian Wine Novel S. cerevisiae yeast strain Research Institute
Tilloy et al. 2014 IONYSWFTM obtained by adaptive evolution in Montpellier, France Commercialised by Lallemand Decreases ethanol and increases glycerol and acidity
Difference observed: 0.4 % v/v to 0.8 % v/v
* average results from over 30 wineries, figures and data from Lallemand technical datasheet The Australian Wine Mutagenesis and selection Research Institute
Lab-scale Chardonnay Anaerobic conditions 22ᵒC ↓ 2.1%
S. cerevisiae LE1 LE2 LE3 LE4 The Australian Wine Non-Saccharomyces strains Research Institute
• 50 Non-Saccharomyces strains • Sequential inoculation • Aerobic and anaerobic conditions The Australian Wine Sequential inoculation Research Institute
S. cerevisiae
Non-Saccharomyces S. cerevisiae The Australian Wine Lab-scale trial - aeration Research Institute
Contreras et al. 2015a Sterile CDGJ Anaerobic Aeration 22ᵒC Aeration 5mL/min
↓ 2.0%
Pilot-scale trials in Shiraz performed last vintage The Australian Wine Lab scale trial - anaerobic Research Institute
Contreras et al. 2014 Contreras et al. 2015b Chardonnay Shiraz (sterile) (non-sterile)
↓ 0.9%
↓ 1.6%
S. cerevisiae M. pulcherrima S. cerevisiae M. pulcherrima S. cerevisiae S. cerevisiae The Australian Wine Lab-scale trial - Shiraz Research Institute
Contreras et al. 2015b M. pulcherrima Wild ferment (Shiraz) (Shiraz) The Australian Wine Shiraz trial - coinoculation Research Institute
Varela et al. 2016
↓ 0.9%
↓ 1.8%
Lab-scale Sterile Shiraz Anaerobic conditions 22ᵒC The Australian Wine Pilot-scale trials – sensory profile Research Institute
Varela et al. 2017 Velcorin®-treated Merlot 30L 22 °C
↓ 0.7% ↓ 1.0%
↓ 1.7% The Australian Wine Post-fermentation technologies Research Institute
Physical removal • Membrane-based systems of alcohol – reverse osmosis – evaporative perstraction • Vacuum distillation • Spinning cone column
These provide effective and precise control of alcohol reduction
All affect volatile composition and depending on ethanol removal they also affect sensory profile and potentially wine style The Australian Wine Sensory effects - summary Research Institute
Longo et al. 2017b
Variety Method Ethanol Sensory impact removed Aglianico EP 2% - 5% Decrease fruity and flowery notes, increase astringency and acid Chardonnay SCC 2% Decrease overall aroma intensity and hot mouthfeel
Merlot RO 2% - 3% Decrease heat and texture, increase astringency and acid Shiraz RO 2% - 5% Decrease balance, persistency and heat
Sauvignon blanc RO 1% - 3% Decrease overall aroma, heat, balance and persistency The Australian Wine Summary Research Institute
• Several strategies available for managing alcohol concentration in wine.
• Different strategies may impact on wine aroma, flavour and/or style.
• Fundamental to understand alcohol preferences by consumers.
• Combination of strategies will most likely affect wine attributes significantly. The Australian Wine Acknowledgements Research Institute The Australian Wine References Research Institute
Bindon et al. 2013 Food Chem 138: 1696-1705 Bindon et al. 2014 Food Chem 154: 90-101 Contreras et al. 2014 Appl Environ Microbiol 80: 1670-1678 Contreras et al. 2015a Int J Food Microbiol 205: 7-15 Contreras et al. 2015b Appl Microbiol Biotech 99: 1885-1895 Godden et al. 2015 Aust J Grape Wine Res 21: 741-753 Longo et al. 2017a J Sci Food Agric doi:10.1002/jsfa.8434 Longo et al. 2017b J Sci Food Agric 97:8-16 Palacios et al. 2007 Aust NZ Grapegrower Winemaker 527: 71-75 Tilloy et al. 2014 Appl Environ Microbiol 80: 2623-2632 Varela et al. 2015 Aust J Grape Wine Res 21: 670-679 Varela et al. 2016 Food Chem 209: 57-64 Varela et al. 2017 Int J Food Microbiol 252: 1-9 The Australian Wine AWRI Research Institute
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