Phenolics of WA State Wines*

Transcription

1 Phenolics of WA State Wines* Jim Harbertson Washington State University * And Grapes!

2 Introduction Impacts of deficit irrigation on grape and wine phenolics Impacts of grape ripening on wine phenolic development

3 Active Volcanic Region Region rich with Volcanic history Basalt foundation for entire Columbia Valley

4 Rain Shadow Effect 300+ Days of Sunshine in Eastern WA The Columbia Valley is protected from wet weather systems by two major mountain ranges, the Olympics and the Cascades, creating the perfect climate for wine in the warm and dry eastern part of the state. Website: Washington State Wine

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6 Daily Sunlight Peak Growing Period 17 hours Equator (0 degrees) 38 degrees North 45 degrees North 12 hours hours 45 Jan Feb Mar Apr May Jun Jul Au g Se p Oc t Nov De c Website: Washington State Wine

7 Diurnal Shift 100 F 80 F 60 F 40 F 20 F Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average High Average Low * Y-axis in Fahrenheit, data points in Celsius Warm Daytime Temps + Chilly Nighttime Temps (17 c / 31 F difference from daytime highs) = Better Color Malic Acid Retention Website: Washington State Wine

8 Two Sets of Experiments Dr. Keller, Dr. Smithyman, Dr. Riley & now Dr. Casassa Cold Creek Vineyard: Cabernet Sauvignon 1 st Exp. When should deficit be applied? Early, Late, or Full? 2 nd Exp. Full season deficit severity and compensation

9 Fruit & Wine Chemistry Industry Standard (IS) fruit & Late Deficit fruit and wine have low phenolics Early and Full Deficit fruit and wines have high phenolics

10 Late Deficit and Industry Standard Wines driven by Red and Brown hue Early and Full Deficit Wines driven by Astringency, Color

11 Anthocyanins & Tannins WA fruit and wine have high concentrations Control from Irrigation Polymeric Pigment Production? Reaction between an anthocyanin and variety of wine components Primarily tannins Stable color: coloration is less effected by ph changes and bisulfite bleaching Formation may decrease astringency sensation Extraction/formation in wine

12 Objective Determine how multiple factors influence polymeric pigment formation and stability over time Maturity Alcohol Anthocyanin:Tannin

13 2015 Impact of Berry Maturity Anthocyanins accumulate between veraison and harvest

14 Fruit to Wine Anthocyanin Harbertson and Keller Am. J. Enol. Vitic. 63:40-48.

15 Fruit to Wine Tannin Harbertson and Keller Am. J. Enol. Vitic. 63:40-48.

16 Winemaking Procedure Syrah and Cabernet Sauvignon Wines replicated sugar content of other maturity treatments Controlled for maturity vs. ethanol effects Fruit Maturity Winery Sugar Treatment 20 Brix Unripe 20 Brix 24 Brix 28 Brix 20 Brix Ripe 24 Brix 24 Brix 28 Brix 20 Brix Experiment designed so wines would have a range of anthocyanin, tannin, and A:T Overripe 28 Brix 24 Brix 28 Brix

17 Aging Wines were collected at day 10 of fermentation Remaining sugars and organic acids were removed (XAD7) Dissolved in same volume model wine (14% alcohol, 5 g/l TA, ph=3.5) Aged at 30 o C for 4 months Samples collected once a month Cellar aged samples collected 6 months after fermentation Analysis of polymeric pigment, anthocyanin, tannin, and total phenolics performed by protein precipitation, HSO 3 - bleaching assays and FeCl 3

18 Cabernet Sauvignon Syrah Harvest (Pick Date) Unripe (DOY 233) Ripe (DOY 260) Overripe (DOY 289) Unripe (DOY 231) Ripe (DOY 252) Overripe (DOY 286) 2015 Harvest Data Brix at Harvest ph ~ 3-4 weeks between pick dates TA (g/l) Berry Weight (g) Anthocyanin (mg/berry) 19.2 c 3.41 c 9.29 a 0.82 b 0.71 c 25.1 b 3.72 b 7.23 b 1.02 a 0.91 a 27.5 a 3.89 a 6.91 c 0.83 b 0.82 b 20.0 c 3.47 c 7.95 a 1.37 a 0.90 c 24.5 b 3.73 b 8.07 a 1.36 a 1.52 a 27.9 a 4.01 a 4.72 b 1.12 b 1.14 b

19 Cabernet Sauvignon Initial Wine Phenolic Data Harvest Date Anthocyanin (mg/l) Tannin (mg/l CE) Ratio A:T Unripe DOY a 1072 a 0.36 a Ripe DOY b 886 b 0.93 b Overripe DOY b 892 b 0.86 b Alcohol Treatment Low a 0.83 Medium a 0.71 High b 0.61

20 Syrah Initial Wine Data Harvest Date Anthocyanin Tannin (mg/l) (mg/l CE) Ratio A:T Unripe DOY c 374 ab 1.3 b Ripe DOY b 351 a 2.1 a Overripe DOY a 429 b 2.0 a Alcohol Treatment Low b 2.1 a Medium a 1.7 b High a 1.6 b

21 Anthocyanin Changes Over Time Independent of alcohol treatment 1 month incubator=1 year cellar Exponential decay R 2 :

22 Polymeric Pigment Over Time 1 month incubator=1 year cellar

23 CS Phenolics

24 CS Confidence Intervals

25 SY Phenolics

26 SY Confidence Intervals

27 Predicting Polymeric Pigment Content (SY)

28 R 2 Values for Other Predictors Syrah A:T=0.042 [Tannin]=0.392 [Anthocyanin]=0.735 [Tannin] + [Anthocyanin]=0.859 Cabernet Sauvignon A:T=0.405 [Tannin]=0.02 [Anthocyanin]=0.670 [Tannin] + [Anthocyanin]=0.767

29 Conclusions Initial wine (not necessarily fruit) anthocyanin concentration best single predictor of longterm polymeric pigment Higher initial anthocyanin (and tannin), higher polymeric pigment More stable color and mouth feel modification over time Polymeric pigment formation occurs relatively rapidly At equilibrium between formation and sedimentation after 1 month (1 year cellar)

30 Future Work Winemaking methods that impact anthocyanin extraction and help polymeric pigment production Heat, extended maceration etc. Methodologies for understanding tannin chemistry Sensory of heated wines

31 Thanks! Funding Source(s): Wine Advisory Committee, the Washington Wine Commission, the Washington Grape and Wine Research Program, and the WSU Agricultural Research Center WSU: Markus Keller, Lynn Mills, Caroline Merrell, Richard Larsen, Maria Mireles Former Student: Federico Casassa (now Cal Poly San Luis Obispo) Family: Eileen, Andrew and Daniel

32 Winemaking Procedure Wines fermented in triplicate 200 L scale, 54 total wines Inoculated with EC 1118 (10 6 cells/ml) Simultaneous ML fermentation (~48 hours post) Nutrient Addition FermaidK (0.25 g/l), DAP (200ppm), GoFerm (0.3g/L) No acidity adjustments Water for saignée/water back had 5 g/l tartaric acid Chaptalization with 80 Brix sugar solution 10 day maceration