Introduction of the
Brettanomyces Impact Wheel
Lucy Joseph
Department of Viticulture and Enology
U.C. Davis
Introduction
• Brettanomyces is considered to be the primary
spoilage yeast in finished wine
• However, many consumers and critics like the
complexity that is derived from Brett growth
in wine
• What accounts for that complexity?
Compounds Produced by Brett in Wine
• Signature spoilage compounds - ethyl phenols,
vinyl phenols
• Other spoilage compounds – acetic acid, ethyl
acetate, fatty acid, carboxylic acid
• Compounds that are positive – Esters, higher
alcohols, terpenes
Strain Collection
Initial Screen
• Defined medium was used
• Supplemented with amino acids
• All strains will make 4EP and 4EG
with coumaric and ferulic acids
Part 1: Initial Screen:
of 2 Strains
InitialSnapshot
Screen
Using these descriptors, do we successfully capture how each strain was perceived?
Strain 2027: 0% liked, 63% disliked, intensity 6.5 (out of 9), (South African beer)
Strain 2066: 35% liked, 35% disliked, intensity 2.7, (Italian wine)
Part 1:
Initial Screenof Descriptors with
Correlation
Intensity and Like/Dislike scores
How does the use of descriptors relate to the like/dislike,
intensity data?
Savory
Animal
Putrid
Solvent
Acetic
Musty
Ferm
Dairy
Spicy
Woody
Floral
Fruity
% POSITIVE
-0.06
0.08
-0.24
-0.02
-0.16
0.05
0.05
0.20
0.11
-0.05
0.07
0.19
0
% NEGATIVE
-0.02
0.05
0.44
0.02
0.11
0.18
0.05
-0.18
-0.1
-0.40
-0.13
-0.29
0.1
% MIXED
0.05
-0.08
-0.36
-0.01
-0.05
-0.22
-0.08
0.09
0.06
0.46
0.11
0.22
-0.12
INTENSITY
0.13
0.05
0.29
0.02
0.12
0.05
-0.34
-0.28
0.01
0.04
-0.08
-0.20
0.18
Correlation of descriptor usage with preference and intensity data
PEARSON: 0.2146 for 82 df, 95% confidence
Veggie
Selection for Test in Wine
• Descriptors, intensity, and likability used to
score strains
• Out of the initial 83 that were successfully
screened in the initial screen, 17 were chosen
as “positive” and 5 as “negative”
Percentage of evaluations
Positive and Negative Perception
100%
90%
80%
%+/-
70%
%-
60%
%+
50%
40%
30%
20%
10%
0%
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83
Strains
Summary of Aroma for Strains Tested
in Wine
Table 5 Aroma summary of strains selected for growth in wine
Likeability
Number of aroma descriptors by category*
Strain
Intensity
+
+/- Sa An R So Ac M Fe D Sp W Fl
Fr
V
605
2.89
16% 58% 26%
0
1
2
4
11
0
4
0
2
1
6
2
0
2404
3.10
10% 40% 50%
0
2
5
5
3
0
8
0
1
1
8
2
1
2051
4.75
8%
42% 50%
3
2
2
4
4
0
5
0
0
1
12
0
0
2408
4.19
19% 44% 38%
0
3
3
3
5
0
4
1
3
4
1
5
0
2504
3.00
19% 31% 50%
1
3
0
1
4
0
5
2
3
5
4
3
1
2402
4.50
25% 13% 63%
2
1
2
2
3
0
4
2
0
2
3
0
0
2406
2.75
13% 50% 38%
1
1
1
2
2
0
2
1
0
3
2
0
0
2509
4.44
8%
50% 42%
0
0
7
0
5
0
2
2
3
2
6
0
0
2066
2.68
40% 30% 29%
1
0
0
3
3
3
4
2
3
0
4
1
1
2091
4.93
0%
42% 58%
1
3
2
3
7
0
4
1
0
5
6
3
2
2752
5.50
0%
38% 63%
0
0
5
4
4
0
1
0
0
3
2
0
0
2508
4.69
0%
58% 42%
0
1
6
2
2
2
3
1
4
3
3
0
3
2385
3.83
0%
45% 55%
0
4
5
4
6
0
8
0
1
3
7
0
0
2505
3.44
0%
50% 50%
0
2
3
2
3
0
7
3
1
5
4
5
0
2092**
6.08
0% 88% 13% 2
1
8
3
6
0
3
0
0
3
4
1
1
2077**
5.00
0% 67% 33% 2
5
6
3
9
0
4
0
1
0
3
0
0
*Sa=savory, An=animal, R=Rotten/Putrid, So=solvent, Ac=acetic, M=musty, Fe=fermentation, D=dairy, Sp=spicy,
W=woody, Fl=floral, Fr=fruity, V=veggie **denotes “negative controls”
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SPME-GCMS
• These strains were also screened chemically
• Used defined medium supplemented with
– Aromatic amino acids
– Cinnamic acids and aromatic amino acids
• Goal was to identify strains that produced low
negative characters
Strains – Aroma Compounds
for differences from control in similar
Acknowledgements
“same” or “different” from
ibe.
Beth Albino
Bisson Lab