Winemaking
Calculations
Amanda Stewart
Purdue Wine Grape Team
29 April 2011
Spring Workshop
Buck Creek Winery
SO2 is on Your Side
 Why?
Microbial Stability
Inhibition of browning enzymes
Binding of acetaldehyde
Antioxidant
 Commercial average 74 mg/L
C. Butzke 2006, Wine Quality Control Basics
Free SO2 and pH
pH
Free SO2
REQUIRED
Free SO2 and pH
Example Calculation
 Assume
1000 gal of wine
pH = 3.44
No SO2 has been added yet
Plan to bottle with residual sugar
How Much SO2?
 For pH = 3.44, we need:
35 mg/L Free SO2
 Plus an extra 30 mg/L to cover losses
 Addition:
35 mg/L + 30 mg/L = 65 mg/L Free SO2
How many grams to put in the tank?
UNITS!
 1 gallon = 3.785 Liters  1 gal/3.785 L = 1
 1 g = 1000 mg  1 g/1000 mg = 1
How many grams?
 Convert F SO2 from mg/L to g/gal
 65 mg/L*(3.785 L/1 gal)*(1 g/1000 mg) = 0.246 g/gal
 Add as Potassium Metabisulfite, (KMB)
 Potassium Metabisulfite is only 58% SO2
 Conversion factor from SO2 to KMB = 1.7
 0.246 g/gal * 1.7 = 0.418 g/gal KMB
 We have 1000 gal of wine, so:
 0.418 g KMB/gal * 1000 gal =
418 g Potassium Metabisulfite
How to Protect the Wine?
 Assume
 1000 gal of wine
 pH = 3.44
 No SO2 added yet
 Plan to bottle with RS
Potassium Sorbate Addition
Potassium Sorbate
Sorbate
Potassium Sorbate
 Target 200 mg/L sorbate
 How many grams to add to our tank?
 200 mg/L *(3.785 L/1 gal)*(1 g/1000 mg) =
0.76 g/gal sorbate
 Potassium Sorbate is only 74% sorbic acid
 Conversion factor: 1.35
 (0.76 g/gal)*1.35 = 1 g/gal
 1 g/gal * 1000 gal = 1000 g potassium sorbate
Gut check
 Potassium metabisulfite:
 Adding 423 g to 1000 gal wine
 Potassium sorbate:
 Adding 1000 g to 1000 gal wine
 Does this seem right?
 Impact on Cold Stability!
 Adding more Potassium
Potassium Sorbate
Weight!
 For bench trials, need to weigh ± 0.01g
 0 – 500g capacity
 For additions of SO2 and Sorbate, need to
weigh ± 1 g
 0 – 2 kg capacity
Gut Check
Material
Potassium
Metabisulfite
(Powder)
Potassium
Sorbate
Sugar, granular
1 cup weighs?
341 g
103 g
200 g
Blending
 Sensory Impact  Requires Blending
Trials
 Chemical Composition  Calculation
Acid
Alcohol
Blending 2 Wines - Alcohol
 Pearson’s Square
a
b-m
Blending to target 12% alcohol
Wine “a” has 11% alcohol
Wine “b” has 14% alcohol
11%
m
b
12%
m-a
14%
14-12=2
 2 Parts A
12-11=1
 1 Part B
3 Parts Total
Blending 2 Wines - TA
 Target 6.5 g/L
a
b-m
m
b
m-a
Wine “a” has 7.1 g/L TA
Wine “b” has 8.9 g/L TA
Blending 2 Wines
 Target TA 6.5 g/L
a
b-m
Wine “a” has 5.4 g/L TA
Wine “b” has 8.9 g/L TA
5.4
m
b
2.4 Parts A
6.5
m-a
8.9
1.1 Parts B
3.5 Parts Total
Blending for TA, cont’d
 Need to use 2.4 Parts A, 1.1 Part B
 Total Volume Desired = 250 gal
 Determine proportions
 3.5 total parts
 2.4 parts A/3.5 total parts = 0.686 A
 1.1 part B/3.5 total parts = 0.314 B
 The whole is the sum of its parts
 A+B = 1
 0.686 + 0.314 = 1
 How much of Wine A and Wine B to make 250 gal
blend?
 A: 250 gal*0.686 = 171.5 gallons of wine A
 B: 250 gal*0.314 = 78.5 gallons of wine B
Sugar Additions
 Large sugar additions increase wine/juice volume
 500 gal of juice at 18 Brix, desired to have 22 Brix
 Need to add ~4% sugar, or 40 g/L
 40 g/L * (3.785 L/1 gal) = 151.4 g/gal
 151.4 g/gal * 500 gal = 75,700 g = 75.7 kg
 75.7 kg * (1 lb/0.454 kg) = 167 lb sugar (!)
Sugar Additions
 How much additional juice volume will result?
 167 lb sugar = 75.7 kg sugar
 Density of CRYSTALLINE SUGAR ≈ 0.85 kg/L
 Density of DISSOLVED SUGAR ≈ 1.7 kg/L
 75.7 L crystalline sugar/1.7 kg/L = 45 L dissolved
sugar
 Final juice volume is increased:
 500 gal + 45 L/(1 gal/3.785 L) =
512 gal
Summary
 Yes, online calculators are available
 Proficiency in winemaking calculations
 Reduce chance of mistakes
 Make additions to juice/wine with confidence
Online Calculator
 http://vinoenology.com/
Questions
Thank You!
HANDOUTS
 Free SO2 and pH chart
 Unit conversions/rules of thumb
 Typed example calculations