hybrid barrel - World Cooperage

RESEARCH
HYBRID BARREL
French Oak Heads and American Oak Staves
Dr. Jennifer Newton and Terry Nolan
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Hybrid Barrel: French Oak Heads and American Oak Staves
1
ABSTRACT
Oak barrels were manufactured using French oak heads and American oak staves. Four such barrels were
produced along with four American oak barrels and four French oak barrels. Chardonnay was produced
sur lie and left in contact with the oak for six months. The wine from each set of barrels was blended and
tested for sensory and chemical analysis. Chemical analysis conducted eight months after bottling found
the Hybrid barrel produced wine with characteristics of both French and American oak. It contained more
oak lactones than the French oaked wine and more oak tannins than the American oaked wine. Its aromatic
oak aldehydes also fell in between the French and American samples. Sensory differences were difficult to
judge. This may have been due to the long time, 14 months, in bottle.
INTRODUCTION
Due to the physiological structure of French oak,
a large portion of the tree cannot be used to make
barrels. French oak has only a small amount of tyloses,
which means that its staves are prone to leaking.
Coopers have overcome this drawback of French oak
by splitting the staves along the grain. However, this
cutting method leaves a large amount of short pieces
unsuitable for stave production but useable for making
barrel heads.
French Oak Head
American Oak Staves
American oak contains sufficient amount of tyloses to
allow it to be sawn. This leads to far less waste and
greater yield for American oak, just one of the reasons
why American oak is less expensive. To maximize the
use of American and French oak, we put the “extra”
French oak heads onto American staves to build a
Hybrid barrel. This created a barrel with 25% French
oak and 75% American oak.
To study the influence this combination barrel had on wine, Benziger Family Winery produced barrel
fermented Chardonnay in it alongside all-French and all-American barrels.
MATERIALS AND METHODS
Chardonnay grapes from Bryton Vineyards, Carneros were crushed on September 11, 1997. Prior
to fermenting 1lb / 1000 gal Bentonite, 1/2 lb / 1000 gal DAP, 1/2 lb / 1000 gal Nutrex were added.
Fermentation was carried out using Cote de Blanc yeast, 1.5 lbs / 1000 gals and it lasted 25 days. During
fermentation, 1 lb / 1000 gal more DAP was added. At the end of fermentation 45 ppm KMBS was added.
Wine was filled into 12 barrels – 4 were American oak, 4 were French oak and 4 were American oak staves
with French oak ends. Wine was matured for 6 months.
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Hybrid Barrel: French Oak Heads and American Oak Staves
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RESULTS
Table 2: Wine analysis
as of December 11, 1997
Table 1: Harvest data of juice
Total acidity 5.5 g/l
59 Gallon
Brix 22.8°B
Alcohol 14.21 % v/v
pH 3.44
Total acidity 6.1 g/l
Solids 0.55%
Volatile acidity 0.46 g/l
The four barrels from each set were mixed to make
three composite wine samples: French, American and
Hybrid. The composite wine samples were analyzed
for wood extractives, smoke components and wine
phenolics. The chemical analysis is given in Table 3.
Free sulfur dioxide 30 ppm
Total sulfur dioxide 73 ppm
pH 3.62
Residual sugar 0.15 %
Table 3: Chemical analysis of finished wine
French Oak
Hybrid
American Oak
1.79
1.81
2
2.14
Furfural 5.19
4.25
6.28
5-methyl furfural 0.43
0.54
0.74
Vanillic acid 0.26
0.39
0.36
Syringic acid 1.32
1.16
1.37
Ellagic acid 2.7
2.81
2.66
Vanillin 0.39
0.44
0.4
Syringaldehyde 0.34
0.37
0.4
Coniferaldehyde 0.02
0.05
0.03
Sinapaldehyde 0.03
0.03
0.04
Trans-lactone 0.024
0.034
0.346
Cis-lactone 0.173
0.237
0.870
Myricetin 0.03
0.02
0.06
Quercetin 0.32
0.48
0.39
Dihydroxybenzoic acid 0.94
0.97
0.91
Catechin 6.07
5.22
5.36
Epicatechin 0.96
1.85
0.59
Chlorogenic acid 3.99
4.26
4.25
Caffaeic acid 2.89
3.44
3.03
0.3
0.27
Guaiacol 0.36
2.06
1.4
M/P-cresol 1.69
3.92
3.83
O-cresol 1.62
2.03
1.8
0
0
0.04
0
0
0
Gallic acid 2.03
Hydroxy methyl furfural 2.18
Phenol 0.18
4-methyl guaiacol 0
4-ethyl phenol 0
4-ethyl guaiacol 0
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Hybrid Barrel: French Oak Heads and American Oak Staves
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Figure 1 is a bar graph comparing the lignin degradation products of the three wines. Lignin degradation
products are aromatic aldehydes extracted from seasoned and toasted oak barrels. They should give the
wine a sweet, rich, vanillin flavor. The wine matured in the 100% American oak barrel had the most lignin
degradation products. However, the Hybrid barrels produced wine with the most vanillin. Vanillin is the
most flavor active of the lignin degradation compounds.
Figure 1: Lignin degradation products in wine matured in French, American and Hybrid barrels
3.0
2.5
Sinapaldehyde
Coniferaldehyde
Syringaldehyde
Vanillin
Syringic acid
Vanillic acid
mg/L
2.0
1.5
1.0
0.5
0.0
French Oak
Hybrid
American Oak
Figure 2 shows the tannin hydrolysis products. Tannins in oak are co-polymers of gallic or ellagic acids with
sugars (mostly glucose), and therefore are called gallitannins and ellagitannins. French oak can contain
ten times more tannins than American oak. It is not surprising that the wine matured in the French oak
barrel contained the most oak non-flavanoids, namely gallic and ellagic acid. The American oaked wine
contained the least.
Figure 2: Tannin content of wines matured in French, American and Hybrid barrels
5.0
4.5
4.0
mg/L
3.5
3.0
Ellagic acid
Gallic acid
2.5
2.0
1.5
1.0
0.5
0.0
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French Oak
Hybrid
American Oak
Hybrid Barrel: French Oak Heads and American Oak Staves
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Figure 3 shows the lactones in the wine. These compounds are responsible for the woody, coconut, oaky
aroma of barrel aged wines. The cis isomer is ten times more flavor active than the trans isomer, and is
more abundant in American oak than French. The French oak barrel produced wine with the least total oak
lactones, and the wine made in the Hybrid barrel did not have significantly more. The American oaked wine
contained the most oak lactones.
Figure 3: Lactone content of wines matured in French, American and Hybrid barrels
0.6
0.5
cis - lactone
trans-lactone
mg/L
0.4
0.3
0.2
0.1
0
French Oak
Hybrid
American Oak
The smoke compounds and sugar caramelization products were highest in the Hybrid barrel (see Table 1).
This would be caused by an inconsistency in toasting amongst the set. The Hybrid barrels may have received
a higher toast than the others, thus producing more sugar caramelization products and smoke phenolics.
In March 1999 a sensory panel assessed the wine using quantitative descriptive analysis. The results are
presented below.
Figure 4: Sensory profile
for French barrel
rich
complexity
2.5
TIA
rich
2
1.5
1
astringent
vanilla
complexity
2.5
TIA
astringent
rich
complexity
2.5
vanilla
1.5
astringent
toasty
sweet
smoky
fruity
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0.5
toasty
bitter
sweet
toasty
bitter
smoky
sulfury
vanilla
1
0.5
bitter
TIA
2
2
1.5
1
0.5
sulfury
Figure 6: Sensory profile
for American barrel
Figure 5: Sensory profile
for Hybrid barrel
fruity
Hybrid Barrel: French Oak Heads and American Oak Staves
smoky
sweet
sulfury
fruity
5
The preference was solidly for the American oaked wine in this tasting with the French oaked wine being
least preferred. The wine made in the American barrel was the most intense, indicated by its high TIA score.
It also scored high in vanillin and smoky aromas. However, its overall score for fruitiness was lower than
the other two samples. The Hybrid and French oak barrels produced subtler more astringent wines. The
astringency could be due to their higher tannin content.
At the 4th International Barrel Symposium, delegates tasted the wines. Comments on sensory perception
and preference scores were taken. Table 4 gives a summary of the tasting.
Table 4: Results from the
4th International Barrel Symposium tasting
Preference
American Oak Barrel 40%
French Oak Barrel 29%
Hybrid Oak Barrel 31%
No clear preference was decided at the Symposium. Additionally the sensory profiling did not find any
statistically significant differences amongst the samples. This may have been due to the wine being in bottle
for over a year. The bottle aging had softened the wine and dulled the oak species influence on flavor.
CONCLUSION
A study into the influence of a Hybrid American/French oak barrel (75:25 ratio) on wine was carried out.
It was found the wine produced in the Hybrid barrel took characteristics from both species of oak. It had
a higher tannin content but less oak lactone than the American oaked wine. Its aromatic oak aldehydes
also fell in between the all-French and all-American levels. Similarly, the quantitative descriptive analysis
described the wine as a blend. An economical choice appears to be available to add up to 25% French oak
character into wine without purchasing an entire French oak barrel.
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Hybrid Barrel: French Oak Heads and American Oak Staves
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