Presentation by Tim Donahue and Sabrina Lueck at VinCO 2014.

1. White Wine Making
Theory and Practice
Tim Donahue and Sabrina Lueck

2. The Walla Walla Center
for Enology and Viticulture

3. Hands-On Learning, World-Class Wines

4. 2013 Wine Awards
2013 Muscat Ottonel - Bronze, Tri-Cities Wine Festival
2012 Estate Semillon - Double Gold, Seattle Wine Awards; Bronze San Francisco Int'l Wine Comp.
2012 Scholarship White - Double Gold, Seattle Wine Awards; Silver, Indy Int'l Wine Comp.
2012 Estate Sauvignon Blanc - Top 50 Regional Wines, Seattle Times; Double Gold, Seattle Wine Awards; Silver,
Indy Int'l Wine Comp.
2012 Riesling - Silver, Indy Int'l Wine Comp.; Silver, Tri-Cities Wine Festival
2012 Muscat Ottonel - Double Gold, Seattle Wine Awards
2012 Mourvedre Rosé - Double Gold, Seattle Wine Awards
2012 Estate Malbec - Bronze, Tri-Cities Wine Festival
2012 Chardonnay - Silver, Indy Int'l Wine Comp.; Silver, Tri-Cities Wine Festival
2012 Estate Carmenere - Double Gold and Best Carmenere, San Francisco Int'l Wine Comp.
2012 Estate Cabernet Sauvignon Ice Wine - Double Gold, Seattle Wine Awards; Silver, Indy Int'l Wine Comp.
2011 Syrah - Gold, Tri-Cities Wine Festival; Silver, Indy Int'l Wine Comp.
2011 Estate Semillon - Silver, San Francisco Chronicle Wine Comp.
2011 Scholarship Red - Double Gold and Best Bordeaux Blend, Indy Int'l Wine Comp.; Silver, Tri-Cities Wine
Festival
2011 Estate Merlot - Silver, Indy Int'l Wine Comp.
2011 Estate Malbec - Gold, Seattle Wine Awards; Silver, San Francisco Int'l Wine Comp.
2011 Estate Cabernet Sauvignon - Silver, Indy Int'l Wine Comp.
2011 Barbera Dessert Wine - Silver, Seattle Wine Awards
2010 Syrah - Bronze, Tri-Cities Wine Festival
2010 Estate President's Blend - Bronze, San Francisco Chronicle Wine Comp.
2010 Estate Merlot - Silver, Seattle Wine Awards; Silver, San Francisco Chronicle Wine Comp.
2008 Syrah - Bronze, Seattle Wine Awards

5. Special Thanks
Gordon Burns, Dr Rich Descenzo,
and the ETS Laboratories team.
Their support empowers us to be
better winemakers and better
educators.

6. Two Part Format
Sabrina
1. Review of chemical parameters
and chemical/biological
processes.
2. Chemical/biological impact on
winemaking processes.
Tim
1. Identifying issues via juice
and wine analysis.
2. Application of chemical and
microbiological concepts easier winemaking, better
wines.

7. Chemical Parameters and
Winemaking “Problems”
Part 1

8. Key Chemical and Microbiological Concepts
•
The chemical parameters that we need to know are in the ETS Labs
juice and chemistry panels
•
Knowing some key concepts empowers us to be better decision
makers
•
Our chemistry is tied to our microbiology
•
Our microbiology is tied to our chemistry
•
Both are tied to sensory perception

9. Chemical Parameters
What’s in our wine?

10. Main Chemical Parameters
Juice (ETS Juice Panel)
pH
Wine (ETS Chem Panel)
pH
Titratable Acidity
Titratable Acidity
Acidity
Tartaric Acid
L-Malic Acid
(L-Malic Acid)
Potassium
Potassium
Brix
Glucose + Fructose
Glucose + Fructose
α-Amino Compounds (NOPA)
Sugar
Nitrogen-Containing
Compounds
Ammonia (FAN)
Yeast Assimilable Nitrogan (YAN)
Free SO2
Total SO2
SO2
Molecular SO2
Volatile Acidity
Acetic Acid / Ethyl Acetate

11. Acid Metrics
pH
Titratable
Acidity
Reflects concentration of free H+
in solution (not a direct value)
pH = -log[H+]
Reflects concentration of
titratable H+
H+ that is free, H+ that is part of COOH groups
•
•
•
•
TA = [H+] + [-COOH]
•
Direct measurement of acid
Direct
species.
Measurement
Tartaric acid and malic acid
•
•
Will influence
molecular SO2
concentration
Will influence
microbial activity
Correlation to sensory
No correlation to
microbial stability
Correlation to sensory
No correlation to
microbial stability
Excellent tool at juice
stage

12. Tartaric and Malic Acid Dissociation
pKa = pH at which concentrations of ionized and partially/un-ionized species are equal
at pKa = 2.98, [H2T] = [HT-]
Lower pKa = stronger acid
(Image: Sacks, 2010)

13. pH < 3.67
H2T
Predominant
equilibrium
H+ + HT-
HT-
HT- + K+ → KHT
•
Implications of
KHT
precipitation
pH > 3.67
•
•
Decrease in TA due to loss of
titratable protons (HT-)
Decrease in pH due to equilibrium
shift to right
System wants to dissociate H2T to
replace lost HT- - will release H+
H+ + T2-
HT- + K+ → KHT
•
•
•
Decrease in TA due to loss of
titratable protons (HT-)
Increase in pH due to
equilibrium shift to the left
System wants to re-associate
T2- and H+ to replace lost HT- will consume H+
We can predict problems by
knowing and understanding
our pH and [K+]!
(Image: Jackson, 2008)

14. Sugar
•
Main species - hexose sugars, glucose and fructose
!
C6H12O6 → 2C2H5OH + 2CO2
•
Both are converted to ethanol
•
Both metabolized to fructose-6-P early on in glycolysis process
•
Helpful to have a glu-fru measurement in juice stage
•
Imperative to have glu-fru measurement at supposed dryness

15. Brix
•
Brix isn’t sugar!
•
•
-2°B ≠ 0 g/L sugar
Measure of total soluble solids
•
Includes non-fermentable sugars, other solids
!
ºBrix x 0.6 = potential ABV (?)
•
Not that clean-cut
•
Many factors influence sugar to alcohol conversion
•
Brix isn’t a direct measure of sugar content

16. Yeast Assimilable Nitrogen
YAN = NH4+ + α-amino compounds
•
α-amino compounds = non-proline amino acids
•
Very important for both flavor production and healthfulness
•
•
•
Conceptually tied to sulfur reduction
Conceptually tied to biogenic amine production
Supplement low YAN with Di Ammonium Phosphate (DAP)
•
We need to know our numbers!
•
Major implications with too much or too little supplementation

17. Free SO2 and Molecular SO2
molecular
SO2 + H2O
+
H
+
pKa = 1.81
bisulfite
HSO3
+
2H
pKa = 7.2
SO2 is in a pH dependent equilibrium
•
Molecular SO2 - the active antimicrobial species
•
Bisulfite - binds to carbonyl compounds rendering them involitile
•
•
Removal of acetaldehyde “bruised apple” aroma
Sulfite - not present in significant quantity at wine pH
+
sulfite
2SO3

18. Figure 1. The percentage of forms of free sulfite over pH 0 to 7
We live here
(Henderson, 2009)

19. Figure 2. Free SO2 concentration required to obtain 0.8 mg/L
molecular SO2 at a given pH
140
Free SO2 Concentration
120
100
80
60
40
20
0
2.90
3.00
3.10
3.20
3.30
3.40
3.50
pH
3.60
3.70
3.80
3.90
4.00

20. Volatile Acidity
•
Two components of volatile acidity - acetic acid and ethyl acetate
•
Ethyl acetate is produced via non-enzymatic esterification with
ethanol
•
Ratio is roughly 5:1 in wine, however detection threshold of ethyl
acetate is 25x higher than acetic acid

21. Volatile Acidity
•
Acetic acid is mainly produced microbiologically
•
•
Acetic acid bacteria, mainly acetobacter - at crush/press, fermentation (in unclean wine), and
aging
•
S. cerevisiae - during stuck or sluggish fermentations
•
Lactic acid bacteria - Oenococcus oeni, Lactobacillus, or Pediococcus during MLF
•
•
“Native” yeast, mainly Hanseniaspora uvarum - at crush/press, early fermentation
Damaged berries, Pichia membranaefaciens in Sour Rot
Converting sugar to acetic acid

22. Winemaking “Problems”
Step by step crisis management

23. Stages To Discuss
Stage
Concern
Enzymatic/chemical oxidation
Crush and Press
Microbial spoilage, volatile acidity production
Cold Settle and
Clairification
Microbial spoilage, volatile acidity production
Primary
Fermentation
Microbial spoilage
Volatile acidity production
Sulfur reduction
Malolactic
Fermentation
Chemical/microbiological oxidation
Volatile acidity production

24. Crush and Press
1. Enzymatic/chemical
oxidation
2. Microbial spoilage
• Volatile acidity production
• YAN depletion

25. 1. Enzymatic Oxidation - Polyphenol Oxidase
•
Polyphenol oxidase oxidizes polyphenols!
•
Converts diphenol groups to quinone groups
•
•
Groups found in caffeic acid, quercetin, B-ring of most flavonoids (condensed tannins and anthocyanins)
Implications - non-enzymatic
-
•
Quinones consume bisulfite (HSO3 ), can consume free SO2
•
Quinones can “capture” thiols
•
•
PPO browning at press - capture of Sauvignon Blanc varietal aromatics (if quinones still present when thiols
are released)
PPO is denatured by SO2 and alcohol
•
Add SO2 at press
•
Minimize air at press - oxidizes with O2
•
PPO isn’t functional in wine

26. 1. Enzymatic Oxidation - Laccase
•
Vector - botrytis bunch rot
•
Main substrate - diphenol, other groups
•
Not denatured by SO2, ethanol
•
Conflicting literature on removal
•
Tannin fining due to low isoelectric point of enzyme (laccase- + tannin+)
(Winesecrets, 2011)
•
Simply bind protein with bentonite (AWRI, 2011)
•
Anecdotal evidence from Tim - laccase removal from Muscat Ottonel

27. 1. Non-Enzymatic Oxidation
•
•
Metal catalyzed oxidation (Cu, Fe)
2+
Cu
•
3+
catalyzes formation of Fe
3+
Fe
•
•
2+
from Fe , and HOO• species
reacts with polyphenols to form quinones
SO2 binding, browning polymerization
HOO• reacts with polyphenols and ethanol (in wine)
•
Quinone formation, aldehyde production
(Danilewicz, 2007)

28. 2. Microbial Spoilage
•
Competitive advantage of spoilage microorganisms at crush/press
•
•
No ethanol
•
•
Oxygen (potentially)
No kill-positive S. cerevisiae
Implications
•
Volatile acidity - sugar to acetic acid in presence of oxygen
•
YAN depletion - consumed by spoilage microbes
•
Down-the-line implications - underfed S. cerevisiae population, H2S libration

29. Cold Settle and
Clarification
1. Reduce biological and nonbiological turbidity
2. Obtain chemical data

30. 1. Reduce Biological and Non-biological Turbidity
•
1-2 punch of cold (<40F) and enzyme - drop
out solids
•
Reduce juice turbidity
•
•
•
Fermenting “dirty” juice - higher fusel oil
production, masking of aromatics
Yeast produce higher reduced sulfur
aromas
Reduce microbial populations
•
Reduce microbial population = reduce
potential for VA
•
Reduce microbial population which is
consuming YAN
(Riberau-Gayon, 2006)

31. 2. Obtain Chemical Data
•
Minimum - pH, TA, Brix, YAN
•
High value in having L-malic and tartaric acids
•
TA isn’t a good indicator of acids in juice (K+ interference)
•
Brix, pH, and potassium give us an idea of pH shift during tartrate
drop
•
Are we going to shift down or up?

32. Fermentation
1. Volatile Acidity
2. Sulfur Reduction
(Image: Napa Valley College)

33. 1. Volatile Acidity Production
•
Did we settle microbes out?
•
•
LABs can convert sugar to acetic acid
Hanseniaspora uvarum have a competitive advantage at the
beginning of ferment
•
Higher population than S. cerevisiae, thrive in warmth and low
alcohol
•
Some strains can produce 25 x normal ferment production
•
Acetic acid will inhibit our yeast

34. 2. Reduced Sulfur Production
(Sacks Lecture, 2010)

35. Mastering Sulfur Reduction - Go Reductive!
“grapefruit, passionfruit”
“passionfruit, tropical”
(Curtin et al., 2008)

36. Malolactic
Fermentation
1. Microbial Spoilage
2. Volatile Acidity Production

37. Factors Inhibiting MLF
•
Think TAPS (thanks Tim)
•
Temperature - above 14C
•
Alcohol - below 15%
•
pH - above 3.05
•
SO2 - below 40 mg/L

38. Practical Tasting
Part 2

39. Key Points
•
Titratable Acidity
•
•
Pretending everything is
Tartaric
•
•
•
•
•
Good for vineyard record
keeping
Depletion during MLF
Potassium
•
•
Buffer capacity
•
Good predictor for sensory
thresholds in wine
Bad for wine production
decision making
Malic Acid
KHT stability
Yeast Assimiliable Nitrogen

40. Disclaimer
•
These wines were not made in triplicate under controlled laboratory
conditions.
•
These wines are commercial wines, in production sized batches (2+
Tons) that are made for sale.
•
Please do not misconstrue the data as being academic and
publishable, it is merely for educational purposes and to illustrate how
a winemaker might react to a given set of conditions. :)

41. Wine #1 Semillon
Student Winemakers: Natalie Jones, Erin Procter, Jack Clapahm-Oeder

42. First Wine: Sémillon
Estate “Stan Clarke” Vineyard
1.99 g of H2M (MW134) = 2.22 g of H2T (MW150)
Remember TA is expressed in “Tartaric Acid Equivalents”
SO if we add up 2.22 g/L + 5.81 = 8.03 g/L of “TA”!!!!

43. Production
Processing
Fermentation
•
Whole bunch pressing in an old “Willmes”
press.
•
Fermented with high biomass yeast (SimiWhite)
•
Oxidative pressing
•
Fermented in 12°C (54°F cellar)
•
No SO2 additions during crushing or
pressing.
•
DAP at 3 stages (18,14 and 10° brix) to
raise YAN to 320 mg/L
•
25 mg/L added at tank for cold settling.
•
Fermentation lasted 16 days
•
Enzymatically settled with pectinase
•
Inoculated with Enoferm Beta (for MLF)
•
0.5 g/L bentonite at the tank
•
•
Cold settled for 48 hours at <5°C (38°F).
MLF conducted in cool cellar to extend
process and increase levels of diacetyl.
(60 days)
•
Racked to 6 neutral barrels

44. Remember to monitor your fermentations!
Brix
Temperature
22
18
14
10
6
2
-2
0.0 1.4 2.0 2.4 3.0 4.1 5.1 5.4 6.0 7.0 7.4 8.0 9.0 9.4 10.0 12.0 13.1 15.1 16.0
Days Since Inoculation

45. Post Fermentation Numbers
•
Remember that TA thing?
•
This influences the decision to undergo MLF!
•
MLF was inoculated in order to reduce the acidity to a more reasonable number.
?

46. Finishing
Aging
•
•
Battonage (stirring) weekly until MLF
complete.
•
Added 60 mg/L of SO2 post MLF
•
No additional bentonite, as wine was
“stable”
Bottling
SO2 to 0.8 mg/L molecular
Barrels topped weekly.
•
SO2 adjusted monthly.
Plate and frame filtered nominally
sterile to 0.46 micron
•
DO2 checked prior to bottling, N
sparge to lower DO2 below 1.0 mg/L
•
Sterile bottled
•
Closed with screwcap with tinsaranex liner.
Aged 6 months “sur-lie”
•
Plate and frame filtered coarse, 2.0
micron.
•
•
•
•
Racked under CO2 blanket to tank 1
week prior to bottling.

47. Bottling Data
•
MLF reduced the titratable acidity to 7.3 g/L
•
Low pH requires low free SO2 to obtain a good molecular SO2
•
•
Remember to “adapt” for DO2 during bottling.
Each 1 mg/L of DO2 removes 4 mg/L of SO2

48. Wine #2 Sauvignon Blanc
Student Winemakers: Marcus Mejiia, Marcus Borron, Cody Janett, Stephen
Moore

49. Second Wine: 2012 Sauvignon Blanc
Stan Clarke “Estate” Vineyard
•
Same harvest date as the Semillon
•
“TA” still doesn’t line up
•
Look at all of that potassium……
3.44

50. Reductive Processing

51. Production
Processing
Fermentation
•
Reductively destemmed/crushed with ≈ 50 lb of
CO2 “snow” per ton and 25 mg/L of SO2 added.
Fermentation started with Tourlaspora delbruckii.
•
•
After 4° brix drop, second inoculum of X-5 yeast to
finish primary.
•
6 hour skin contact with a cellulase enzyme
•
Reductively in membrane press
•
Waited for DAP addition until obvious H2S liberation.
(WHAT?)
•
25 mg/L of SO2 added during press cycles in 5mg/
L increments.
•
Then DAP added to raise YAN to 320 mg/L at 15°
brix
•
Fermentation in jacketed SS tank to maintain 1° brix
drop per day
•
Temp range between 17 to 8.5°C.
•
•
•
•
•
!
Transferred under CO2 to tank.
Press fraction treated with 10 g/HL of PVPP then
combined with free run.
Enzymatically settled with pectinase
0.5 g/L bentonite at the tank
Cold settled for 48 hours at <5°C (38°F).
!
!
!

52. Brix
Temperature
22
18
14
10
6
2
-2
0
3.3
4.4
5.3
6.4
7.6
8.7
9.7
Days Since Inoculation
10.7
12.3
13.4
15.4

53. Post Fermentation Numbers
•
Again, the TA rises, but in proportion to the actual sum of acids in the wine.
•
Potassium may still cause further de-acidification due to KHT formation.
•
Lastly, just because a hydrometer reads -2° brix, doesn’t mean you are DRY.
•
Confirm dryness!
?

54. Finishing
Aging
•
P+F filtered coarse, 2.0 micron.
•
60 mg/L SO2 at end of primary
•
De-acidification/mutage trials
•
Racked 1 month post primary
•
Mutage with concentrate to 3 g/L RS
•
SO2 maintained at 0.8 mg/L molecular
and adjusted monthly.
Bottling
•
•
•
•
•
P+F filtered nominally sterile to 0.46
micron
Heat stability verified via Bentotest™
Bentonite added at 0.25 g/L (after
trials)
•
Racked under CO2 blanket to tank 1
week prior to bottling.
DO2 checked prior to bottling, N sparge
to lower DO2 below 1.0 mg/L
•
Sterile bottled closed with screwcap
with tin-saranex liner.
Cold stabilized via 2 week cold hold at
-2°C

55. Bottling Data
•
Note lower TA post cold
stabilization.
•
Higher SO2 additions required
because of higher SO2 added
at crush.

56. Wine #3 Muscat Ottonel
Grown by Chef Greg Schnorr

57. Third Wine: 2013 Muscat Ottonel
Schnorr Vineyard
•
Juice Panel: When your pH is higher than your TA…
•
17° Brix, powdery mildew. Good times!

58. Production Notes
Day 1
•
1 g/L malic acid added (TA equivalent)
•
100 mg/L SO2 at the crusher
•
25 kg/T of CO2 snow
•
Juice split 70% for wine
•
Cold soak in press for 24 hours
•
30% for juice
•
Juice sorbated 150mg/L as sorbic acid
Day 2
Day 4
•
Pressed reductively
•
100 mg/L SO2
•
Laccase positive
•
Moved to fridge
•
1 g/L Bentonite
•
Laccase check – clean!
•
0.1 g/L “FT–Rouge Soft”
•
Rack to fermentation tank under blanket of CO2
•
Pectinase for settling
•
Inoculated with Zymaflore Alpha (Tourlaspora delbruckii)
•
Finished with QA-23
•
100 mg/L Dap addition at 2nd inoculation.
Day 3
•
60 g/L of C+H’s finest!
•
1 g/L tartaric Acid added

59. Brix
Temperature
22
18
14
10
6
2
-2
0
1.8
2.9
4
5.7
6.7
8.6
10
11.1
12
Days Since Inoculation
13
13.9 15.6 16.6 17.6

60. Production Notes
Day 14-24 - Cold stabilization (sort
of….)
Day 26
•
Confirm sorbate level via ETS
•
Cellulose gum added at 1ml/L tartrates + bubbles = :(
Day 24 - Crossflow filter
Day 25
•
Mutage (juice add back)
•
Day 28 - Sterile bottle on 6 spout hand
bottling line.
Sterile filter (nominal)
Day 29 - Sales begin…..
•
•
Potassium sorbate bump to 120
mg/L
SO2 bump to 1.0 mg/L molecular
SO2
Bigger goal – sell it out ASAP to pay for
your red wine habit….

61. Bottling Data
•
Sold out by Christmas
•
Initial sales in the first
week covered all
production costs.
•
Sales by Christmas
covered ALL barrel
expenses for College
Cellars….
•
Cash-flow
winemaking!

63. References
Henderson, P. 2009. Sulfur Dioxide. Practical Winery and Vineyard Journal. January/February.
Danilewicz, J.C. 2007. Interaction of Sulfur Dioxide, Polyphenols, and Oxygen in a Wine-Model
System: Central Role of Iron and Copper. Am. J. Enol. Vitic. 58:53-60
Ribereau-Gayon, P., Dubourdieu, D., Doneche, B., and A. Lonvaud. 2006. Handbook of Enology
Volume 1 The Microbiology of Wine and Vinifications. John Wiley & Sons, West Sussex, UK.
Curtin, C., King, E., Kievit, R.L., Ugliano, M., Henschke, P., and P. Chambers. 2008. Optimizing
Wine Quality through the Application of Flavour-Active Yeast Strains and Nutrients. In
Proceedings of Les XXes Entretiens Scientifiques Lallemand. pp 25-35. Lallemand SAS,
Toulouse.
Sweigers, J.H., Bartowsky, E.J., Henschke, P.A. and I.S Pretorius. 2005. Yeast and bacterial
modulation of wine aroma and flavour. Australian Journal of Grape and Wine Research. 11:
139-173.
Jackson, R.S. 2008. Wine Science Principles and Applications. Academic Press, Burlington, MA.