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Wine Making

0118 This is very rudimentary. The grape harvest takes

place in the second fortnight of October. About

90% of the production is mechanically harvested.

Then the grapes are pressed in horizontal presses.

The continuous presses (called the Archimedes

screw) are prohibited because they may induce herb-

aceous tastes. Sulfur dioxide is not used because it

binds ethanal which is then released during distilla-

tion and tastes pungent. Nor is there any racking of

the lees before fermentation (de

bourbage), and

addition of sugar to the must to increase the potential

alcoholic strength (chaptalization) is strictly

prohibited.

0119 Sometimes, alcoholic fermentation starts badly in

cold and rainy years, but generally it is very fast (8

days for the first vat), then 3–5 days, when the wine

material has been used and allows seeding of musts.

0120 The wines are kept on the lees, and malolactic

fermentation is conducted in the month following

alcoholic fermentation, even if the pH is low, because

absolutely no sulfur dioxide is used.

0121 Distillation can immediately take place after the

end of the fermentations, and the best brandies are

those which are distilled first. Ethyl butyrate levels

increase with time of conservation and especially

when the temperature increases. This is explained by

the total absence of disinfectants to protect the wine

against oxidation and bacterial accidents. As long as

the wine ferments, the medium is reduced (low oxi-

doreduction potential) and there is no risk. However,

at the end of fermentation, the wine must be stored in

full, hermetically closed vats. The most frequent acci-

dent is the browning of wine (casse brune) caused by

an enzymatic oxidation of the phenols in quinones in

years of rot. It seems that this has no effect on the

quality of the spirits since the polyphenol does not

distil.

0122The bacterial risks are the bacterial degradation of

tartaric acid call tourne (which is far from frequent),

and the problem of bitterness due to acrolein which

arises from the decomposition of glycerol in prope-

nal. This is not very frequent but is very harmful

for the brandies, which then become undrinkable.

Several cases occurred in the past when the tanks

were situated under the ground; the wine cooled too

slowly and lactic bacteria degraded the glycerol and

butanediol. Since the use of disinfectants is pro-

hibited, it is obviously necessary to work with per-

fectly clean wine-making equipment because of

possible contamination. The screw of the press must

be lubricated with paraffin oil because mineral oil

could give a tainted taste to the Cognac.

Wines

0123The alcoholic strength is generally relatively low

(8–10% vol). The wines are too acid for direct con-

sumption at pH 3 or even less, and total acidity ranges

CHALAIS

MONTLIEU

BEAUVOIR

BARBEZIEUX

BLANZAC

ANGOULEME

LA ROCHEFOUCAUD

JARNAC

JONZAC

MARENNES

GEMOZAC

ST PORCHAIRE

ROCHEFORT

TONNAY CHARENTE

PONS

ROYAN

OCEAN ATLANTIQUE

GIRONDE

SEUDRE

CHARENTE

COGNAC

LA ROCHELLE

SAINTES

AULNAY

ST JEAN D ’ANGELY

MACQUEVILLE

MATHA

RUFFEC

AIGRE

GRANDE

CHAMPAGNE

PETITE

CHAMPAGNE

FINS BOIS

BONS BOIS

BOIS

CORDINAIRES

BORDERIES

SEGONZAC

ILE DE RE

ILE D ’OLERON

fig0009 Figure 9 (see color plate 11) Cognac in France and the different appellation areas. See text for further details.

BRANDY AND COGNAC/Armagnac, Brandy, and Cognac and their Manufacture 595

from 7 to 10 g l

1

(expressed as tartaric acid), even if

malolactic fermentation has taken place. The acidity

of the must reaches 15–20 g l

1

. This acidity makes it

possible to some extent to compensate for the absence

of sulfur dioxide. However, according to regulations,

the wines must be distilled before the end of March

because after that time heat would lead to inevitable

deterioration caused by the growth of lactic bacteria.

These wines contain only very little ethanal since

sulfur dioxide is not used.

0124 The flavor must be very neutral. When the specific

fruitiness of the type of grape is too marked, it is not

possible to obtain fine brandies. For example, musca-

delle or sauvignon cultivars would not be suitable to

obtain good Cognac. In contrast, with the very neu-

tral Ugni blanc, the flavor comes from fermentation

byproducts. This flavor is probably mainly due to

higher alcohols which are present in high quantities,

since fermentation occurs in the presence of the less of

the must (see Table 1). The esters of fatty acids, ethyl

caproate, caprylate, caprate, and laurate are also

important because of a relatively low fermentation

temperature (late grape harvest, low sugar content).

0125 The herbaceous tastes in Cognac are due to car-

bonyl compounds with six carbons. They may occur

when the harvested grapes contain too many leaves or

when they are crushed too hard by the machines. Oily

tastes are due to 1,1,6-trimethyl-1,2-dihydronaphta-

lene (TDN) for the same reasons. This chemical sub-

stance seems to be more or less specific to Ugni blanc,

especially when it is not ripe enough.

0126 Volatile acidity is generally very low (0.2–0.4 g l

1

expressed in acetic acid). Ethyl acetate levels are also

generally low (30–60 mg l

1

). The dry extract varies

between 15 and 24 g l

1

. The quantity of unfermented

sugar is very low, and often nil (less than 50 mg l

1

Distillation

0127The charentais still (Figure 10) The charentais still

is made of copper of electrolytic quality (no hydrogen

bubbles in metal). Copper is essential since it is a good

conductor, is not attacked by wine acids, and fixes the

traces of H

S arising from the late treatment of the

vine with sulfur to combat oidium infection. Copper

combines a part of the caprylic, caproic, and lauric

fatty acids, whose odor resembles that of cheese, and

long-chain fatty acids which could give insoluble

soaps (eliminated by filtration). Distillation in a stain-

less-steel boiler gives poor-quality brandies. The pro-

cess can be improved by adding turnings of copper or

copper sulfate. The copper is rolled and hammered to

increase its hardness and to make its surface

smoother.

0128There are two shapes of stills according to the

shape of the boiler, which is either straight or onion-

shaped. The volume of the boiler is 30 hl maximum

for the second distillation called the bonne chauffe;

exceptionally, the volume of the boiler may be

150 hl but only for the distillation of the wine (first

distillation).

0129The upper part is called the chapiteau (olive or

onion form). Its volume represents 10% of the

volume of the boiler and it is topped by the swan

neck. A wine heater generally makes it possible to

recover the calories provided by the alcoholic vapors.

The temperature is about 50



C before the boiler is

filled. The serpentine, which is also made of copper,

is about 30 m long. It is placed in the cooler, called

Swan neck

Wine heater

Cooler

Cold water

Alcohol meter holder

Washy wine

Furnace

Boiler

Chapiteau

fig0010 Figure 10 Charente still for the production of Cognac spirit.

596 BRANDY AND COGNAC/Armagnac, Brandy, and Cognac and their Manufacture

la pipe, which is filled with water; its capacity is

approximately twice that of the boiler.

0130 The boiler is assembled on a solid mass of masonry.

The boiler is heated by direct flame (no steam or

electric heating). At the lower part is the furnace.

On the sides of the boiler are what is known as the

‘turns with fire’ in which the gases from the hearth are

burned before being evacuated towards the chimney.

From 600



C in the hearth, the evacuated gases drop

to no more than 250



0131 The liquid in the boiler is at boiling point (between

90 and 102



C) and the temperature in the chapiteau

is lower than 5–8



C. Part of the vapor (3–5%) flows

back, which makes it possible to obtain a slight recti-

fication of the distillate. At 1 mm above the bottom of

the boiler, there occurs an overheating of about 5



before boiling begins. Excessive overheating induces a

certain bitterness of the spirit.

0132 Formerly wood was used as fuel, then coal, and

nowadays butane and generally propane. It is obvi-

ously necessary to use burners which work efficiently

without overheating. The adjustments are similar to

those of a central heating system.

0133 Distillation method Traditionally the wines are dis-

tilled with their lees. However, in recent years only

the finest lees (yeast) have been used, so it is possible

to speak of wines with fine lees or even wines free of

lees. This has repercussions on the ester content

(Table 4).

0134First distillation or distillation of the wine, known as

chauffe du brouillis The boiler is filled to 95% of its

volume. The wine boils after 1.5 h of heating, and the

distillate which runs out first contains 55–60% vol of

alcohol. Distillation takes place until all alcohol is

distilled and is stopped when the distillate contains

2% vol. The liquid thus collected is called the brouil-

lis, its alcoholic strength ranges from 26 to 31% vol.

It is obtained in approximately 12 h. The temperature

of flowing distillate must be about 15



0135Second distillation, called the bonne chauffe This is

carried out under the same conditions. After 1.5 h of

heating, the distillate starts to run out. It contains

75–80% vol of alcohol: 1% of total volume collected

constitutes the heads which are separated and mixed

with wine or brouillis. The distillate is collected up to

60% vol of alcohol; this is the heart, whose average

alcoholic strength is nearly 70% vol. The distillate

which then runs out is called the seconds (which taste

of fat); these seconds are mixed with wine or brouillis

to be redistilled.

0136The temperature of the distillate which runs out of

the cooler must be about 18



C to obtain a good

brandy. The rate of flow is 1 l min

1

0137The seconds can either be mixed with the wine and

in this case the alcoholic strength is not of major

importance (first principle, Figure 11), or they may

be added to the brouillis, in which case the strength is

28% vol. Therefore, it may be necessary to reduce the

distillation of the brouillis according to the alcoholic

strength of the initial wine (second principle, Figure

12). In this case the seconds are redistilled only once,

which increases the strength of the brouillis.

0138The second distillation is performed at a lower

temperature, thus obtaining better rectification of

the spirit. Here, the tails of the brouillis need to be

cut.

0139There are also variants of these two methods. Vary-

ing the intensity of heating is important according to

the strength of brouillis required. Slow distillation

gives good rectification. An odorous fine brandy is

obtained but with dryness that may be detected on

tasting due to the lack of certain products of tail

distillation (e.g., ethyl lactate, diethyl succinate). In

contrast, fast heating involves the formation of a

marrowy brandy with little bouquet. Excessive

heating results in a heavy taste.

Aging

0140The cognac ages in barrels of between 200 and 600 l.

The barrels must be in oak of special quality. Trad-

itionally these oaks came from the forests of Tronc¸ais,

Allier, Limousin, and the Vosges in France. The stave

woods, i.e., pieces of wood used to make the barrels,

tbl0004 Table 4 Effect of the lees of the wine on the composition of the

distillate

Fewleesin thewine Withleesin the wine

Ethyl caproate 6.76 8.3

Ethyl caprylate 8.95 23.6

Ethyl caprate 13.8 63

Ethyl laurate 12.45 36.2

Ethyl myristate 5.4 9.8

Ethyl palmitate 9.77 13.2

Ethyl palmitoleate 1.44 1.8

Ethyl stearate 0.59 0.61

Ethyl oleate 1.19 1.22

Ethyl linoleate 7.69 9.2

Ethyl linolenate 1.86 2.58

Isoamyl caprylate 0.42 2.48

Isoamyl caprate 1.67 5.76

Isoamyl laurate 0.78 1.83

2-phenylethyl caprylate Traces 1.2

2-phenylethyl caprate 0.25 1.55

Summ of aromatic esters 73.02 186.65

(þ150%)

Results as mg l

1

of the distillate at 70% vol.

Reproduced from Cantagrel R, Lurton L, Vidal JP and Galy B (1992) La

distillation caharentaise pour L’obtention des eaux-de-vie de Cognac. In:

Bertrand A (ed.) Les Eaux-de-vie Traditionnelles d’Origine Viticole, pp. 60–69.

Paris: TEC & DOC, with permission.

BRANDY AND COGNAC/Armagnac, Brandy, and Cognac and their Manufacture 597

must be stored for 3 years outside so that the bitter

substances that they contain are transformed by en-

zymatic reaction. The meta-digallic acid is hydro-

lyzed into the less aggressive gallic acid. The same

occurs with aesculine and scopoline, glucosides that

are transformed into aesculetine and scopoletine,

which are less bitter. The transformations can take

place only with time; fast drying obtained by stoving

(heating) is not sufficient and the brandies placed in

such barrels are bitter.

0141During aging the brandy is oxidized slowly. Its

acidity grows by oxidation of alcohol into volatile

(a) (b)

% vol.

Brouillis

920 l 30% vol.

Wine: 2227 l at 9% vol.

+ heads 19 l at 66.5% vol. (10 l 57% vol. + 25 l 78% vol. 3 4/11)

+ seconds 254 l at 30% vol. (700 l 3 4/11)

Heads, 10 l 57% vol.

Mixture: 2500 l at 11.6% vol. Brouillis 2500 l at 30% vol.

Heart

(Cognac)

730 l 70% vol.

Heads 25 l 78% vol.

Seconds

700 l 30% vol.

123456789101112

fig0011 Figure 11 Distillation of the cognac, first principle. (a) First distillation of the wine, to obtain the broiullis; (b) second distillation,

bonne chauffe. Eleven brouillis must be distilled to give four bonnes chauffes.

(a) (b)

% vol.

Tails

120 l 3% vol.

Brouillis

800 l 27% vol.

Wine: 2324 l at 9% vol.

+ heads: 21 l at 66% vol. (10 l 55% vol. + 24 l 76% vol. 3 4/9)

+ tails: 155 l at 3% vol. (120 l + 78 l 3 4/9)

Heads, 10 l 55% vol.

Mixture: 2500 l at 9.1% vol. Mixture: 2432 l at 27.8% vol.

Brouillis: 1800 l at 27% vol.

+ seconds 632 l at 30% vol.

Heart

(Cognac)

662 l 70% vol.

Heads 24 l 76% vol.

Seconds

632 l 30% vol.

123456789101112

Tails

78 l 3% vol.

fig0012 Figure 12 Distillation of the cognac, second principle. (a) First distillation of the wine to obtain the brouillis; (b) second distillation,

bonne chauffe. Nine brouillis must be distilled to give four bonnes chauffes, and all the tails are mixed with the wine.

598 BRANDY AND COGNAC/Armagnac, Brandy, and Cognac and their Manufacture

acids and by dissolution of the acid substances in the

wood. Moreover, acetals are formed, and their odors

are softer than those of aldehydes. The odor charac-

teristic of young brandy becomes blurred, and even-

tually disappears, to be replaced by a vanilla odor

induced by vanillic aldehyde, together with other

phenolic aldehydes and acids arising from the alco-

holysis of lignin in oak wood. The color becomes

brown by dissolution of tannin. Moreover, the taste

softens with the appearance of sugars arising from the

hydrolysis of wood hemicelluloses.

0142 There is also the appearance of a rancid taste by

oxidation of fatty acids. Several stages in aging may

be distinguished:

0143 From 1.5 to 5 years the main process is dissolution

of substances in the wood.

0144 By 5–10 years astringency decreases and the

brandy becomes rounder.

0145 From 10 to 35 years a rancio taste appears.

0146 After 40 years one should no longer keep brandies

out of the barrel.

A barrel can yield substances to the cognac for about

40 years.

0147 During aging, there is a loss of volume known as

‘the angels’ share.’ This represents 3% on average per

year, with a 1% vol reduction in the alcoholic

strength.

0148During conservation there is little evolution of the

volatile substances. The alcohols concentrate, the

esters are slightly hydrolyzed, and the unsaturated

fatty acids oxidize, which gives the rancio taste. The

Cognac ages by slow oxidation in barrels. In bottles

there is no further evolution.

Analysis

0149Traditional analyses Their purpose is to determine

real and raw volume percentages of alcohol (titra-

tion), dry extract, total acidity, and the ratio of non-

alcoholic elements, i.e., volatile acidity, aldehydes,

esters, furfural, and higher alcohols; methanol values

are determined separately.

0150Table 1 shows values for Cognac compared to

those of brandy and Armagnac. The sum of volatile

substances of Cognac is very high because the distil-

lation process does not eliminate higher alcohols;

however some tail products such as volatile acidity

are noticeably lower than in Armagnac.

0151Gas chromatography Gas chromatography is used

to analyze volatile compounds. As an example, the

chromatogram in Figure 13 shows some of the vola-

tile alcohols, esters, acids, and various aromatic com-

ponents contained in an ether-hexane extract of

VSOP cognac. Other analyses can be carried out by

injecting the spirits directly into the chromatograph.

min

0 10 20 30 40 50 60 70 80 90

fig0013 Figure 13 Chromatogram of the extract of a Cognac by ether hexane (concentration about three times); column FFAP

50 m 0.22 mm; injection according to splitless mode; temperature programming from 40 to 200



C. Identification of the peaks: 1,

Ethyl butyrate; 2, 2-methylpropan-1-ol; 3, isoamyl acetate; 4, isoamyl alcohols; 5, ethyl hexanoate; 6, hexyl acetate; 7, styrene; 8,

acetoin; 9, ethyl heptanoate; 10, ethyl lactate; 11, hexan-1-ol; 12, trans-hex-3-en-1-ol; 13, cis-hex-3-en-1-ol; 14, octan-3-ol (internal

standard 1); 15, trans-hex-2-en-1-ol; 16, ethyl octanoate; 17, trans-linalol oxide (furane); 18, furfural, 19, acetic acid; 20, benzaldehyde;

21, vitispirane; 22, linalol; 23, ethyl decanoate; 24, butyric acid; 25, 3-methylbutyric acid; 26, diethyl succinate; 27, a-terpineol; 28, 1,1,6-

trimethyl-1,2-dihydronaphthalene (TDN); 29, methionol; 30, unknown; 31, unknown; 32, damascenone; 33, phenylethyl acetate; 34, ethyl

dodecanoate þhexanoic acid; 35, benzyl alcohol 36, trans-whisky lactone; 37, 2-phenylethanol; 38; cis-whisky lactone; 39, 4-ethylgaia-

col; 40, nerolidol þethyl myristate; 41, octanoic acid; 42, 4-allylgaiacol (eugenol); 43, 4-ethylphenol; 44, ethyl palmitate; 45, decanoic

acid; 46, ethyl stearate; 47, ethyl oleate; 48, dodecanoic acid; 49, ethyl linoleate; 50, ethyl linolenate; 51, unknown; 52, myristic acid; 53,

palmitic acid; 54, palmitoleic; 55, linoleic acid.

BRANDY AND COGNAC/Armagnac, Brandy, and Cognac and their Manufacture 599

The high levels of esters and fatty acids indicate that

wine is distilled with lees (yeast).

Disturbances and Deposits

0152 These can be:

0153 of organic nature: insolubilization of certain sub-

stances when the temperature decreases; to avoid

this accident the brandies are filtered cold after

cooling at 5



0154 of mineral origin due to calcium arising from the

barrels (1–1.5 mg in 15 years’ storage) or from

the filter plates, thus requiring the use of plates

without CaCO

. Beyond 3 mg l

1

the brandy de-

posits at cold temperature. Certain treatments by

ion exchange resins could be used to eliminate the

excess of calcium and copper.

Preparation for Commercialization

0155 During aging, once a year, the cognac is racked and

all the barrels of the same production are mixed

together. The alcoholic strength is gradually dimin-

ished by adding demineralized water to finally obtain

an alcoholic strength of 40.0% vol in commercialized

bottles (never less). During aging it is common to mix

spirits of different origins, quality and age in order

always to obtain the same odor and taste for a given

brand name. For instance, some Cognac firms use up

to 60 different brandies to prepare their blend but the

brand name (i.e., ***, VSOP) must consider only the

youngest spirit of the blend.

0156 The color can be adjusted with the addition of

caramel. The taste can be adjusted with the addition

of woody water extract obtained from small pieces of

oak wood to give more body to the spirit, more

astringency, and a little bitterness. On the other

hand, excessive hardness can be diminished by the

addition of sucrose syrup, generally less than 8 g l

1

Generally, all these procedures should be carried out

at least 2 or 3 months before bottling.

Tasting

0157 Just as for wines, the length of a brandy can be

measured by taking it into the mouth, spitting it out,

and counting the number of seconds during which an

intense aromatic persistence may be perceived, just

before the appearance of a certain dryness. The word

‘caudalies’ is used to indicate the number of seconds

elapsed. For a Grande Champagne Cognac the sensa-

tion lasts 7–12 s; for Bois ordinaire Cognac it is

only 2 s.

0158 The Grande Champagne In addition to the length

of aromatic persistence, this brandy is characterized

by a bouquet of great smoothness and distinction,

odors of vine flower, dried lime, flowers and dry

vine shoots.

0159The Petite Champagne The same characters are

found but are less accentuated.

0160Borderies The persistence is the same as in Petite

Champagne. These brandies have a developed odor

which is more suave than that of the champagnes. At

the time of the folle blanche before 1880, brandies

had an odor of violet. Unlike in Armagnac, this is not

considered a quality in Cognac spirits. They are less

light than the Champagnes.

0161Fins bois The fins Bois brandies are rounder than

the Champagnes. They are more marrowy but have

a heavier odor more reminiscent of the fruit than

the flower. From the point of view of character, the

length decreases. They age faster, so together with

the bons bois producting *** and VSOP Cognac,

they constitute the most readily available of the

Cognacs.

Acknowledgments

0162The author is grateful to the Bureau Interprofession-

nel de l’Armagnac for its collaboration and financial

support in the form of research contracts, and to his

students at the Institute of Oenology: P. Wildbolz,

Ph. Jadeau, Miss M.C. Segur, Miss S. Biau, M.K.

Bertsch, Miss R. Vanderlinde, and E. Herve.

See also: Alcohol: Properties and Determination;

Metabolism, Beneficial Effects, and Toxicology; Alcohol

Consumption; Brandy and Cognac: Chemical

Composition and Analysis of Cognac; Grapes; Sensory

Evaluation: Aroma; Taste

Further Reading

Bertrand A (1988) Role of the continuous distillation pro-

cess on the quality of Armagnac. In: Piggott JR and

Paterson A (eds) Distilled Beverage Flavour. Recent

Developments, pp. 97–115. Edinburgh: Ellis Horwood.

Bertrand A (1989) L’analyse chimique et sensorielle d’eaux-

de-vie d’Armagnac. Conse

quence de la technologie

sur la qualite

. In: La Re

glementation Communautaire

des Eaux-de-vie et des Liqueurs, vol. 9, pp. 101–111.

Verona: Bollettino del Cideao OIV (ed.).

Bertrand A and Segur M-C (1991) L’alambic armagnacais.

In: Bertrand A (ed.) Les Eaux-de-vie Traditionnelles

d’Origine Viticole, pp. 70–74. Paris: Lavoisier-TEC &

DOC.

Bertsch K (1992) Les Eaux-de-vie d’Armagnac, Crite

res

Analytiques de Qualite

tude sur le Carbamate

d’E

thyle. Thesis: l’ Universite

de Bordeaux II.

600 BRANDY AND COGNAC/Armagnac, Brandy, and Cognac and their Manufacture

Cantagrel R, Lurton L, Vidal JP and Galy B (1992) La

distillation caharentaise pour l’obtention des eaux-

de-vie de Cognac. In: Bertrand A (ed.) Les Eaux-de-vie

Traditionnelles d’Origine Viticole, pp. 60–69. Paris:

TEC & DOC.

Casamayor P and Cousteaux F (1985) Le Guide de l’Ama-

teur d’Armagnac. Toulouse: Laffont/Briand.

Caumeil M (1983) Le Cognac. Pour la Science December:

48–57.

Dufor H (1982) Armagnac – eaux-de-vie et terroir. Tou-

louse: Privat.

Guigon D and Cogat P (1991) Elimination des de

fauts dans

les eaux-de-vie de vin traditionnelles. In: Bertrand A

(ed.) Les Eaux-de-vie Traditionnelles d’Origine Viticole

pp. 110–113. Paris: Lavoisier-TEC & DOC.

Jadeau P (1987) Incidence du De

bourbage des Mou

ts et de

la Fermentation Malolactique des Vins sur la Compos-

ition des Eaux-de-vie d’Armagnac. Thesis: Universite

Bordeaux II.

Lafon J, Couillad P and Gay-Bellyle F (1973) Le Cognac, sa

Distillation. Paris: JB Bailliere.

Marche M and Joseph E (1975) Etude the

orique sur le

cognac. Revue Francaise d’Oenologie 57: 1–22.

Mariller C (1925) Distillation et Rectification des Liquides

Industriels. Paris: Dunod.

Puech J-L (1986) Le vieillissement de eaux-de-vie. In: Les

Aro

mes des Vins. Montpellier: Journe

e de Rencontres

Œnologiques.

Roget J and Garreau C (1991) Recherches sur l’origine de la

distillation et la pre

paration de l’alcool. In: Bertrand A

(ed.) Les Eaux-de-vie Traditionnelles d’Origine Viticole,

pp. 54–59. Paris: Lavoisier-TEC & DOC.

Segur M-C (1988) Approche de la De

gustation Analytique

des Eaux-de-vie d’Armagnac. Interpre

tation Statistique.

Thesis: Universite

de Bordeaux II.

Sempe A (1988) La Grande Messe de l’Armagnac. Paris:

Laffont.

Chemical Composition and

Analysis of Cognac

R Cantagrel, Bureau National Interprofessionnel du

Cognac (BNIC), Cognac, France

Introduction

0001 Cognac is one of the most prestigious products in

the world. It has received an ‘Appellation d’Origine

Contro

e’ or registered designation of origin, and

the term ‘Cognac’ must only be used for spirits from

Cognac or the Charente region. It is subject to strict

production regulations to guarantee origin and

quality.

0002Cognac is characterized by a rich aroma and flavor,

which distinguishes it from other spirits distilled from

wine, the production of which is not governed by

such strict regulations.

Chemical Composition and Sources of

Variations

0003The aroma of Cognac is the result of the characteristic

aromas of many of its constituents, enhanced or

modified by synergistic or masking effects. More

than 500 substances have been detected in spirits;

they belong to a large number of chemical classes:

alcohols (ethanol, methanol, higher alcohols, etc.),

aldehydes, esters, volatile acids (acetic acid, fatty

acids, etc.), ketones, acetals, nitrogen-, oxygen- and

sulfur-containing heterocyclic compounds, phenolic

acids, and aldehydes. These different aromatic con-

stituents are contributed by:

0004the grape (primary aromas);

0005wine-making (fermentation aromas);

0006distillation (specific aromas produced by the

heating process);

0007aging (aromas imparted by the oak wood).

The main aim in the production of a spirit is to form

pleasant, distinctive flavors and fragrances to be

conveyed by the alcohol. (See Wines: Production of

Table Wines.)

0008The quality of a given Cognac depends on a

number of factors:

0009In the production process, variations can be due

to:

0010the weather conditions, which may vary from

year to year, causing differences in the chemical

composition of the resulting wines and spirits;

0011the diversity of grape producers;

0012the different ‘crus’ or growth regions within the

area of designated origin;

0013the several hundered distillers;

0014the several types of stills used with different

distillation methods.

0015In the aging process, variations can be due to:

0016the origin of the oak wood used for the barrels or

casks;

0017cask-making techniques;

0018the layout and geographical location of the cellar

(chai) where the spirits are aged;

0019the length of the aging period.

Variability of the Raw Material

0020The wines used in producing Cognac spirits are made

essentially from the Ugni-blanc grape variety, which

BRANDY AND COGNAC/Chemical Composition and Analysis of Cognac 601

produces wine with a relatively low alcohol content

(generally 8–10% v/v) and a fairly high acidity (6–

12 g of sulfuric acid per liter). This high degree of

acidity ensures good conservation before distillation.

Most of the constituents that make up a Cognac are

present in the wine and lees used in the distillation.

0021 Weather conditions are never the same from one

year to the next. They determine the size of the grape

harvest and the different qualities of wine produced

by the vineyard. For example, the average alcoholic

strengths (v/v) of wines over the last 12 years in

Cognac were:

0022 1987, 7.5%;

0023 1988, 9.6%;

0024 1989, 10.9%;

0025 1990, 9.8%;

0026 1991, 9.6%;

0027 1992, 8.0%;

0028 1993, 7.8%;

0029 1994, 8.6%;

0030 1995, 9.7%;

0031 1996, 9.8%;

0032 1997, 10.3%;

0033 1998, 9.2%.

As a result, the chemical composition of the resulting

spirits varies from year to year.

0034 The figures below illustrate the diversity of the raw

material obtained:

0035 the total area of the registered designation region is

80 000 ha, comprising six growth zones (‘crus’)

within the designation region;

0036 the number of grape growers producing the white

wine sold for Cognac is 8000;

0037 the number of producers with vineyards larger than

3 ha is 5000;

0038 the number of industrial-scale distillers is 150;

0039 the number of growers distilling on their own

premises is 2500.

Cognac is an internationally recognized product,

highly specific, and yet obtained from a number of

different sources.

0040 During the distillation period (about 5 months), the

composition of the wines varies (see Table 1). The

higher alcohol and polyol content does not change,

but there is a significant decrease in the content of

esters with aromatic properties of interest (isoamyl,

hexyl and phenylethyl acetates, ethyl caproate,

caprylate, caprate and laurate) and an increase in

ethyl acetate, ethyl lactate, diethyl succinate, acetal-

dehyde (ethanal) and acetic acid. For this reason, the

distillation is not performed in the same way in

November, when the fermentation is completed, as

in March.

Charente Distillation Method

0041The distillation period in Charente begins as soon as

the alcohol fermentation ends (generally the begin-

ning of November) and continues until March 31.

0042The Charente method of distillation is performed

in two stages. From the first distillation stage, the

brouillis (27–30% (v/v) alcohol) is obtained; the

second distillation stage yields the bonne chauffe

(70% (v/v) alcohol). The purpose of this is threefold:

0043To extract the volatile compounds contained in

the wines used. Besides water and alcohol (etha-

nol), other compounds contribute more through

their intense characteristics rather than their

quantities; they represent 0.3–1% (v/v) of the

alcohol.

0044To select (rectification) from among the volatile

substances present with the alcohol. Certain

highly volatile products are undesirable at high

doses (ethanal, ethyl acetate, acetal, etc.).

0045To perform certain chemical transformations

favorable to the quality of the spirit. The heating

time has a decisive influence on the combination

and decomposition of compounds.

This reactive function of the Charente pot still is the

source of chemical reactions such as:

0046Esterification/hydrolysis:

Acid þ Alcohol Ð Ester þ Water:

0047Acetal formation:

Aldehyde þ Alcohol Ð Acetal þ Water:

0048Maillard reaction:

Sugar þ Amino acid ! Pyrazine; Furans ðcocoa

flavorsÞ:

tbl0001Table 1 Variations in the concentration of wine constituents

during storage for 5 months

Constituents Variation (%)

Ethyl acetate þ24.1

Isoamyl acetate 1

55.7

Hexyl acetate 2

60.7

Phenylethyl acetate 3

62.1

Ethyl caproate 4

22.0

Ethyl caprylate 5

14.2

Ethyl caprate 6

18.9

Ethyl laurate 7

52.0

Total esters 1–7

25.8

Ethyl lactate þ49.1

Diethyl succinate þ226

Acetaldehyde (ethanal) þ117

Acetic acid þ18.8

Organoleptically aromatic esters present in wine in low quantities. Ethyl

acetate and ethyl lactate concentrations are much higher.

602 BRANDY AND COGNAC/Chemical Composition and Analysis of Cognac

0049 Strecker degradation:

a-Amino acid ! Aldehydes ! Acetals:

0050 In order to prevent a coarse character appearing in

the spirits, the wines are generally racked in order to

leave only part of the lees. In keeping with tradition

and local custom, the natural wine is distilled on fine

lees. But of course, each firm gives its distillers spe-

cific instructions in order to obtain products in keep-

ing with the distinctive types they each market. These

instructions concern in particular the proportion of

fine lees that must be kept in the wines used. Obvi-

ously, as a result, there are considerable analytical

differences among the various finished products.

The presence of lees results in a greater quantity of

aromatic esters, which have a high sensory impact,

and produces spirits higher in floral aromas (Table 2).

Care must be taken that the lees are of good quality; if

not, they are a major source of defects.

0051 Given the very high number of chemical classes

present in wines, all wine aromas that are volatile or

carried over by water–alcohol vapors do not pass

over with the same speed during distillation.

0052 Obtaining a good-quality spirit necessarily implies

a harmonious balance of all the constituents: the

distiller’s entire art is required to achieve this balance.

Aging Cognac

The Contribution to Product Diversity

0053 Aging is a basic factor in the quality of Cognacs; it is

also the most costly. Cognac can be kept for many

years in oak barrels; the longer the aging, the more

the intrinsic quality is enhanced. In order to maintain

this quality, the producer is very careful in producing

and aging the product.

0054Aging is an active process, and there are several

parameters that must be controlled:

0055the cellar or chai;

0056the humidity;

0057the temperature;

0058the type of container used for aging.

0059The cellar may have an earthen floor, which pro-

vides good humidity, or it may be made of cement, in

which case, the humidity is lower. The degree of

humidity influences the evaporation rate. In a dry

cellar, evaporation will consist mainly of water loss.

In a very humid cellar, evaporation will affect mainly

the alcoholic strength as alcohol is lost; Cognacs will

then be smoother and mellower, and have a greater

‘rancio’ taste.

0060Difference in Cognac temperature from 7



Con

average in winter to 22



C in summer are reasonable.

This is one of the factors in the ability of a cellar to age

spirits. Chemical reactions occurring during aging

depend on the temperature (esterification, for

example).

0061There are several types of containers. There are

1000- and 50 000-l barrels (for delivery of Cognac

and blends) and casks of 100, 270, 350, 400, and

550 l (aging). Currently, most casks are of the 350-l

type manufactured by coopers (cask makers). The

cask performs several functions during aging. (See

Barrels: Wines, Spirits, and Other Beverages.)

Quality Factors

0062The oak imparts aromatic elements to the Cognac in

greater or lesser amounts according to:

0063the choice of oak – coarse grain oak imparts

tannins more easily than fine grain;

0064the amount of time the staves are allowed to dry

and their thickness;

0065the method of heating when bending the staves to

make the casks;

0066the alcoholic strength of the spirits during aging;

0067the age of the cask or barrel;

0068the grape production zone (‘crus’) and the distilla-

tion method.

Oak wood consists of cellulose (wood fiber), hemi-

celluloses, lignin, and tannins. Tannins are highly

soluble in spirits.

0069The first notable modification during aging is the

change in color. This phenomenon is directly linked to

the extraction and oxidation of tannins. As a direct

result, a young Cognac in a new cask will color

tbl0002 Table 2 Effect of lees on ester contents (mg l

1

spirit at 70%

vol.)

Distillation

Constituents With fewlees Withlees

Ethyl caproate 6.76 8.3

Ethyl caprylate 8.95 23.6

Ethyl caprate 13.8 63.0

Ethyl laurate 12.45 36.2

Ethyl myristate 5.4 9.8

Ethyl palmitate 9.77 13.2

Ethyl palmitoleate 1.44 1.8

Ethyl stearate 0.59 0.61

Ethyl oleate 1.19 1.22

Ethyl linoleate 7.69 9.52

Ethyl linolenate 1.86 2.58

Isoamyl caprylate 0.42 2.48

Isoamyl caprate 1.67 5.76

Isoamyl laurate 0.78 1.83

2-Phenylethyl caprylate Trace 1.20

2-Phenylethyl caprate 0.25 1.55

Total aromatic esters 73.02 182.65

(¼þ150%)

BRANDY AND COGNAC/Chemical Composition and Analysis of Cognac 603

quickly, even excessively, if kept there for a long time,

whereas a young Cognac in an old cask will change

color more slowly, remaining clear even after several

years. Excess tannin (bitter taste) is often associated

with a very high degree of extracted colour. (See

Tannins and Polyphenols.)

0070 The aromatic aldehydes, mainly vanillin, appear

when the lignin breaks down. They are produced by

aging and are very important for the bouquet of

Cognac. Different types of casks result in substantial

variations to their contents of these substances. These

aldehydes, predominantly vanillin, contribute a

vanilla note, which is not too heavy and is greatly

appreciated.

0071 The stave acts as a selective membrane enabling

exchanges to take place between the Cognac within

the cask and the air in the cellar by way of the evap-

oration of the most volatile and smallest molecules, a

phenomenon that contributes to oxidation.

0072 The quality of a Cognac’s aging is measured by its

‘rancio taste’ (hydrolyses of fatty acid esters together

with oxidation and transformation into ketones). The

formation of the rancio taste during aging is accom-

panied by the continual extraction of tannins, slow

oxidation, and various chemical reactions. (See Fatty

Acids: Properties.)

0073 The conditions necessary to make a good cask

container are:

0074 the use of good-quality wood;

0075 the use of wood dried in the open air, exposed to

inclement weather for at least 3 years;

0076 the careful preparation of a new cask and the judi-

cious racking into older casks after proper storage

of the recently distilled Cognac in new casks.

0077 Important research work on the aging of Cognac

spirits has been a major contribution in identifying

the molecules extracted from the oak by the spirits

and in understanding the reaction mechanisms under-

lying the aging process.

0078 The development of gas–liquid chromatography

(GLC) and high-performance liquid chromatog-

raphy (HPLC) techniques has enabled the analytical

changes noted during aging to be quantified with

greater detail. Several aspects of variations observed

in the aging of Cognacs are shown in Tables 3 and 4

by way of example. The extraction of gallic acid is

much greater in a cask made of coarse grain oak,

35.7 mg l

1

compared with 14.5 mg l

1

in a cask

made of fine grain wood. In an old cask, the extration

of phenolic compounds is less (Table 3), but the

oxidation and exchange with the atmosphere con-

tinue to occur. (See Pesticides and Herbicides: Types,

Uses, and Determination of Herbicides; Phenolic

Compounds.)

0079Cognac is sold throughout the world mainly under

commercial designations; among those currently in

use are III, VSOP, Napoleon, and X.O. These

commercial qualities correspond with products of

different ages. The price increases with age. These

commercial products are obtained through blends

(also called ‘coupes’) of different cognacs. Each dealer

has their own blending technique and style. The blend

of different Cognacs is above all a subjective choice. It

enables a representative product of constant and re-

producible quality to be obtained. Blending is there-

fore an important step in the production of Cognac,

since it is the key link between production and

marketing.

Sensory Analysis

0080Cognac spirits are obtained from different ‘crus’ or

growth zones within the area of designated origin:

Grande Champagne, Petite Champagne, Borderies,

Fins Bois, Bons Bois, and Bois Ordinaires. They

show major sensory differences (see Table 5). The

blending of several crus influences the quality of the

product. (See Sensory Evaluation: Sensory Character-

istics of Human Foods.)

tbl0003Table 3 Effect of cask on a spirit aged 13 years

Concentrations (mg l

1

)

Constituent New cask Old cask

Gallic acid 15.3 5.4

Vanillic acid 2.8 1.0

Syringic acid 7.0 2.2

5-Hydroxymethylfurfural 6.3 1.8

Furfural 21.3 10.8

5-Methylfurfural 1.6 0.2

Vanillin 8.8 2.9

Syringaldehyde 17.6 4.6

Coniferaldehyde 6.7 0.6

Sinapaldehyde 17.0 1.7

tbl0004Table 4 Effect of length of aging period

Concentrations (mg l

1

)

Constituent 0.7 years 5 years 13 years

Gallic acid 4.6 9.0 15.3

Vanillic acid 0.3 1.4 2.8

Syringic acid 0.6 2.6 7.0

5-Hydroxymethylfurfural 4.2 4.2 6.3

Furfural 26.8 24.7 21.3

5-Methylfurfural 1.5 1.4 1.6

Vanillin 0.9 4.4 8.8

Syringaldehyde 2.25 8.9 17.6

Coniferaldehyde 3.65 5.9 6.7

Sinapaldehyde 9.45 17.8 17.0

604 BRANDY AND COGNAC/Chemical Composition and Analysis of Cognac