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Brandy and Cognac: Manufacture and Chemical Composition

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Abstract

Brandy and cognac are spirits with common features that have been derived from the distillation of wine, which is fermented grape juice. Topics in the production process and composition, which vary greatly depending on the variety and origin of grapes used, method of must extraction, alcoholic fermentation, distillation processes, the type of wooden barrels used during aging and length of maturation, and the final blending ratio, are highlighted and assessed.
404
Review
Received: 19 May 2013 Revised: 13 August 2013 Accepted article published: 28 August 2013 Published online in Wiley Online Library: 2 October 2013
(wileyonlinelibrary.com) DOI 10.1002/jsfa.6377
Grape brandy production, composition
and sensory evaluation
Argyrios Tsakiris,aStamatina Kallithrakaband Yiannis Kourkoutasc
Abstract
Grape brandy is a spirit drink produced by wine distillation and is matured in wooden casks. According to legislation, it can be
characterised by the geographical area where the grapes were produced, the grape variety used and the selected distillation
and ageing techniques. Distillation increases ethanol concentration and aromatic constituents which are already present in
grapes or are developed during fermentation and distillation. During maturation in wooden casks, compounds that contribute
to the aroma and taste are extracted from the wood. Hence the spirit acquires the desired softer mouth feel, aromatic complexity
and overall quality. Different methods of analysis are used in order to pursuit this process by analysing volatile and non-volatile
substances and correlate composition with quality. Analysis can also be useful in identification of brandy safety, potential
adulterations, provenance and differentiation from other spirits drinks.
c
2013 Society of Chemical Industry
Keywords: brandy; grape; wine; distillation; ageing; quality
INTRODUCTION
Geographical origin and legislation
Brandy is produced in several regions of the world. Globally,
brandy (with 1.2 billion litres) is the fifth largest category of
spirits drink (20.0 billion litres in total). Today, the biggest selling
brandies in the world come from India and the Philippines. It can be
characterised according to the geographical area where the grapes
are produced, the grape variety used and the selected distillation
and ageing techniques employed. According to the European
Union legislation1brandy is a spirit drink (alcoholic beverage)
produced from wine spirit, whether or not wine distillate has
been added, distilled at less than 94.8% (v/v), provided that the
distillate does not exceed a maximum of 50% of the alcoholic
content of the finished product. It should be matured for at least
1 year in oak receptacles or for at least 6 months in oak casks
with a capacity of less than 1000 L. It must also contain a quantity
of volatile substances equal to or exceeding 1.25 g L1of pure
alcohol (125 grams per hectolitre of 100% vol alcohol) and must
possess a maximum methanol content of 2.0 g L1of pure alcohol
(200 grams per hectolitre of 100% vol alcohol). According to the
same regulations, wine spirits are produced exclusively by the
distillation at less than 86% (v/v) of wine or wine fortified for
distillation or by the re-distillation of a wine distillate at less than
86% (v/v). The most famous French wine spirits are those of the
regions of Cognac and Armagnac. Cognac is a double-distilled
spirit in pot still. In Armagnac, distillation takes place in alembic
Armagnacais, a continuous column still with 515 plates. Well-
known Spanish brandies are those originating from the region of
Jeres, which have aged in used sherry casks. A solera system is
followed similar to that used for sherry wine. The most known
South American brandy is Pisco. In Peru it is made mainly from
Muscat grapes. In Chile it is made from different varieties, and
is distilled in pot stills. Italian brandies are not produced within
the borders of specified geographical areas. They are made from
regional wine grapes and are mainly produced by column stills,
although there are also a number of low-scale producers which
employ pot stills. German brandy, which is called weinbrand
(‘burnt wine’), is made from imported wine. Contemporary United
State brandies in California are made mostly by column stills.
According to U.S. legislation,2fruit brandies, derived from grapes,
are labelled as ‘grape brandy’ or ‘brandy’. When brandy has been
stored in oak containers for less than 2 years, it must be labelled
as ‘immature’. It is obvious that, worldwide, there are various legal
definitions according to the national traditions and commercial
interests.
Grapes and treatments before fermentations
In order to produce 1 L of brandy, about 4.5 L of wine are required.
The condensation which takes place during the distillation process
causes a significant increase of aromatic compounds, which is
responsible for the intense and strong flavour of brandy. For this
reason, in brandy production, the usage of neutral flavour grapes,
such as Ugni blanc, is favoured.3The utilisation of such grapes
ensures a satisfactory yield of production in combination with
Correspondence to: Argyrios Tsakiris, Department of Enology & Beverage
Technology, Faculty of Food Technology and Nutrition, Technological
Educational Institute (T.E.I.) of Athens, Ag. Spiridonos Str, Egaleo, 12210 Athens,
Greece. E-mail: atsakiris@teiath.gr
aDepartmentof Enology &BeverageTechnology, Faculty ofFoodTechnology and
Nutrition, Technological Educational Institute (T.E.I.) of Athens, Ag. Spiridonos
Str, Egaleo, 12210 Athens, Greece
bDepartment of Food Science and Technology, Agricultural University of Athens,
Iera Odos 75, 11855 Athens, Greece
cApplied Microbiology and Molecular Biotechnology Research Group,
Department of Molecular Biology & Genetics, Democritus University of Thrace,
Dragana, 68100 Alexandroupolis, Greece
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Grape brandy production, composition and evaluation www.soci.org
the relatively low cost of the raw material. Since the flavour of
brandy derives mainly from compounds that are formed during
alcoholic fermentation, quality grapes are not suitable for brandy
production. For example, aromatic grape varieties with strong
and persistent flavour, such as Sauvignon blanc or Chardonnay,
with low yield and high cost, produce wines of high quality but
are unsuitable for brandy production. For some Pisco brandy,
producers use varieties such as Muscat with more intense varietal
aromas due to the presence of terpenes4since their concentration
diminishes during distillation.5
Sometimes, in order to enhance vine defence, the application
of pesticides is necessary. Although pesticides may have an
influence on the fermentation process, they do not affect the
sensory quality of the wine. In contrast, the addition of sulfur by
spraying or dusting on vine can produce nasty reduction odours.6
Pesticides applied in vineyards may remain on grapes and during
distillation they may be transferred into the distillate. This can only
happen when their concentration is high enough since they are
characterised by low transfer rates.7The Botrytis cinerea infection
of grapes has a negative effect on the quality of both wines and
spirits since mould odours can be detected even after distillation
and ageing. Measurement of the concentration of selected
volatile compounds, such as 1-octen-3-ol, is often employed in
order to monitor the growth of Botrytis cinerea during grape
maturation.8
The harvest should be done mechanically or by hand at the
proper time, not necessarily coinciding with the maximum of
sugars. Grapes must be transported as quickly as possible to the
winery for must extraction and the putrid grapes are removed with
careful screening. Must extraction and vilification is similar to the
white wine making.
The stalks are removed from grapes which are then crushed
and pressed. The must production should be made in such
a way as to extract as few as possible phenolic compounds,
especially tannins. For this reason, discontinuous presses are
used. Continuous presses have the disadvantage of increasing
the sediment of grapes and release undesirable compounds. In
contrast to modern white wine making, must is not clarified by
racking of the lees. The presence and the proportion of lees
affects the composition of wine and consequently the quality
of distillates since it increases their aromatic complexity.9The
time that elapses between pressing and the start of fermentation
should be the minimum possible. This is due to the absence
of sulfur dioxide which protects must and wine from oxidation
and microbial spoilage. Only the must which is produced by the
application of low pressure (about 80% of the total must) is used for
brandy production. Must which is extracted using high pressure
is usually fermented separately and is distilled in a continuous
column still to produce pure alcohol. The addition of pectolytic
enzymes to musts to aid clarification increases the methanol
content of the distillate10 and thus it should be avoided. Moreover,
the concentration of higher alcohols increases when no racking of
the lees takes place.
In general, musts and wines are not treated with sulfur dioxide
since the latter could be transferred into the distillate and thus
decrease its quality by neutralising the aromatic perception. In
certain cases, however, where the hygienic condition of the grapes
is not adequate, 0.01 g L1sulfur dioxide could be added to must
in order to avoid the appearance of ethyl acetate and ethyl lactate.
The above-mentioned volatile compounds could be synthesised
by certain strains of bacteria which can grow in the absence of
sulfur dioxide.9
Fermentation
Wine for brandy production is produced from the must by yeast
fermentation. Brandy production is a traditional process and,
therefore, few innovations are employed as far as fermentation,
distillation and ageing processes are concerned. Alcoholic
fermentation of must occurs mainly by spontaneous fermentation
by indigenous Saccharomyces serevisiae yeasts. Immobilised yeast
cells have also been employed for base wine production due to
their higher productivity and the reduced cost of the final product.
Loukatos et al.11 proposed that delignified cellulose, gluten and
kissiris-supported biocatalysis may have a different effect on the
concentration of amyl alcohols of the distillate. Immobilised cell
reactor was also used to produce ethanol.12 The reactor was
coupled with a distillation column for recycling the effluent from
the bottom of the column.
The presence of lactic acid bacteria also influences the quality
of wine and brandy.13 Different strains of lactic acid bacteria
were isolated from grape must at different stages of brandy base
wine production in South African vineyards and wineries. The
presence of Lactobacillus spp. was correlated with a decrease in
base wine and distillate quality. In contrast, Oenococcus oeni strains
were found to have a more favourable influence on base wine and
distillate flavour.
Between fermentation and distillation
During the period between fermentation and distillation, which
may last up to 5 months, several chemical reactions take place
and the wine composition alters. Care should be taken to keep
this period as short as possible. Distillation can immediately occur
after the end of fermentation. Wine higher alcohol and polyol
content is not influenced by the time that elapses after the end of
fermentation, in contrast with its ester content which can decrease
significantly. The most affected esters are those which possess the
aromatic properties of interest (such as isoamyl, hexyl acetate,
phenylethyl acetate, ethyl caproate, ethyl caprylate, ethyl caprate
and ethyl laurate). An undesirable increase in ethyl acetate, ethyl
lactate, diethyl succinate, acetaldehyde (ethanal) and acetic acid
of the base wine content is usually observed simultaneously.14
Distillation
Either batch or continuous processing is used for base wine
distillation. In batch distillation by pot still, the first distillation
or distillation of the wine takes place until almost all ethanol is
distilled. In the second distillation, about 1% of total volume is
collected separately and constitutes the ‘head’, while the distillate
which contains less than 86% (v/v), about 70% (v/v) of ethanol,
constitutes the ‘heart’. It is the ‘wine spirit’. Finally, the distillate
which then runs out, the ‘tail’, is collected separately until almost
all ethanol is distilled.
In a small continuous still, distillation is performed in column
stills consisting of 515 plates in order to produce the ‘wine spirit’.
Distillation towers (3040 plates) are used in order to produce
‘wine distillates’ with less than 94.8% (v/v). This type of distillate
contains only a small portion of the volatile substances. This is
the reason brandies produced with the addition of such distillates
are less aromatic. In continuous distillation process, wine lees are
removed just before distillation since their presence could block
the distillation equipment and delay the whole process.
Wine is a colloidal suspension that contains several hundred
components in small proportions. Among these, some trace
components are considered as positive quality factors in contrast
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to some other compounds that are deleterious to distillate quality.
In fact, all substances contribute to the complexity and quality of
the distillate when they do not exceed a certain concentration.
During the distillation process, volatile components are extracted
from wine and are concentrated into the distillate. The aim of the
distillation is to recover the maximum amount of ethanol and the
positive characteristic aromas, while minimising the off-flavours in
the distillate.
Lately, modelling and simulation of the distillation process have
been employed in order to apply the optimal operation policies
and to maximise both the production and the quality of brandy.
Osorio et al.5developed a model by the use of neural networks
which describes wine distillation as a multi-component reactive
batch distillation process.
During the process of distillation, a number of chemical reactions
take place together with the extraction of the volatile compounds.
These reactions, which involve15 esterifications, acetalisations,
Maillard reactions and Strecker degradations, can greatly affect
spirit quality. Thus, in order to modify the spirit composition,
the distillers mainly control two parameters: wine flow rate and
temperature of distillation.
Wine distillation is a traditional technique which has been
intensively investigated. Some researchers focussed on the
partial or total removal of ethanol from the spirits in order to
produce reduced-alcohol or alcohol-free drinks. The processes
employed for the production of such alcoholic drinks include
distillation, membrane separation, reverse osmosis, solvent
extraction and supercritical fluid extraction using a counter-
current supercritical fluid extraction system.16 In addition, air-
gap membrane distillation was studied as a possible technique
for ethanolwater separation using polyvinylidene difluoride
membranes.17
Several books18 22 describe the equipment, processes and
particularities applied in distillation, depending on the country
and place of production.
Ageing of distillates in wooden casks
Maturation and ageing of the distillates (‘wine distillate’ or ‘wine
spirit’) is carried out in wooden, mostly oak, casks. This process may
last from several months to several years. Relatively new distillates
are placed in casks with maximum capacity of 2251000 L, while
more aged distillates can be stored in 5000-L casks. During this
period, there is a loss of 23.5% of the distillate per year due to
evaporation.
During the ageing process, the brandy acquires a very
characteristic flavour distinctly different from that of the fresh
distillate. The sensory attributes of the distillates such as colour,
flavour and taste are greatly influenced by the botanical species
of the wood, the different heat treatments applied to wooden
barrels, the times that the wooden barrel has been used and
the ageing time. The complexity of brandy aroma increases
due to the extraction of certain wood compounds (volatile and
non-volatile) into the distillate. For instance, tannins, which are
polymeric phenolic substances, are extracted from the wood
and contribute to the flavour of brandy. In addition, some other
reactions between the components of wood and distillates may
also occur during barrel ageing which can also contribute to the
brandy complexity. The presence of scopoletin [determined with
high-performance liquid chromatography (HPLC)] is considered as
proof of maturation in oak barrels.23
The different volatile compounds extracted from the wood
(lactones, furanic compounds, vanillin derivatives and phenol
derivatives) have important sensory properties. These compounds
have been significantly correlated with several olfactory attributes,
such as vanilla, smoke, toasted and dried fruits, which are positively
correlated with the overall brandy quality.24
The aged distillates can be classified according to their aroma
and taste, by the use of adequate and reliable expert systems
based on fuzzy logic and neural networks. Fuzzy classifier and a
neural network was used25 for the classification of wine distillates.
The fuzzy classifier was based on the fuzzy algorithm, while the
neural system was a feed-forward sigmoidal multilayer network.
Mixing and bottling
In order to obtain the final product, various distillates of different
age from different casks are mixed and pure water is added
to accomplish an alcoholic degree of 40% (v/v). In most cases,
caramel is also added since it contributes to the development of
the colour. Cold stabilisation usually follows to ensure the removal
of the excess quantity of ingredients, such as tannins, which could
develop turbidity and thus affect the quality of the final product.19
Brandy is stabilised after 2 days at 4C. Finally, filtration and
bottling follow. The presence of the fatty acid ethyl esters in
quantities higher than 5 mg Llmay cause deterioration in the
quality of the bottled spirit,26 depending on the alcoholic degree
of the product and the storage temperature.
Hazard analysis of critical control points
Alcoholic beverages control and safety can be assured within
the frame of strict adherence to quality and safety systems,
such as ISO 9000 series, hazard analysis of critical control points
(HACCP) and total quality management (TQM).23 Although the
alcoholic beverages are comparatively safer than other foods and
drinks because of their high alcohol content, identification of
potential hazards and resumption of preventive and corrective
actions (when required) is of primary importance. In recent years,
adulteration (e.g. use of low-cost inappropriate alcohol) has made
rapid progress in this field.
Efstratiadis and Arvanitogiannis27 implemented HACCP for a
large-scale brandy-producing company, as part of the total quality
system. In such a way, it was possible to produce a safer product,
free of heavy metals and methanol.
COMPOSITION
Since brandy is a product of wine distillation, it does not contain
the non-distillable wine organic and inorganic compounds. The
absence of non-volatile organic acids in the distillate affects the
balance of the taste. The brandy’s high alcohol content, about 40%
(v/v), ‘burns’ the mouth and simultaneously augments the sweet
taste.
Brandies, which are usually matured in oak casks for several
years, present a very complex aroma profile. In fact, hundreds
of volatile compounds have been identified in grape brandies.
Some of these volatiles are already present in grapes (primary
aromas) and in wines (fermentation aromas), while some others are
formed during the distillation process (specific aromas produced
by the heating process) or they are extracted from the oak wood.
Among them, acetaldehyde, ethyl acetate, methanol, 1-propanol,
isobutanol, and isoamyl alcohol are present in relatively large
amounts, generally between 50 and 2000 mg Ll,andtheycanbe
easily determined directly by gas chromatography (GC) employing
internal standards. Usually GC is coupled with mass spectrometry
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(MS) where a simultaneous search of a library database is also
possible.28 However, some other important aroma compounds
generated during grape ripening (varietal aroma compounds
such as monoterpenes), and during alcoholic fermentation
(fermentation aroma compounds, such as higher alcohols, middle-
chain mono-carboxylic acids and mono-carboxylic acids), are
usually present at concentrations ranging from 0 to 50 mg Ll
and their determination requires the use of an isolation and
pre-concentration technique.29 For the quantification of such
compounds several authors used liquid –liquid extraction followed
by a concentration step, prior to analysis by GC, but other
techniques have also been proposed, i.e. headspace with solid-
phase micro-extraction (SPME). SPME is actually one of the most
used methods for the analysis of a very wide range of compounds.
The SPME method was successfully applied30 to determine the
differences in volatile concentration of grape distillates produced
by crushed, pressed and fermented grapes. In addition, a stir bar
sorptive extraction method coupled to gas chromatography –mass
spectrometry (GC-MS) has been developed for the analysis of
volatile compounds in brandy. A rapid extraction of aroma
compounds from grape brandies was proposed31 by using
ultrasonication. All classic analytical methods concerning spirits
are described by Bertrand.32
Although the volatile composition of brandies is qualitatively
rather similar, their organoleptic characteristics are often quite
distinct. This can be attributed to the slight differences that
exist between their volatile concentrations.33 Wine distillates
authentication, mainly in terms of varieties and regions of
geographical origin, is rather difficult.34 However, differentiation
can be realised by the utilisation of statistical methods, such as
principal component analysis.
Volatile compounds
The flavourful distilled beverages are highly complex mixtures con-
taining hundreds of individual compounds in an ethanolwater
matrix, enhanced or modified by synergistic or masking effects.
Their role in the formation of wine flavour is dependent upon
their abundance and odour thresholds.35 The odour threshold is
defined as the minimum amount of odorant which must be added
to a reference matrix to cause a significant sensory difference. It
is different in pure water and in model dilute alcohol solutions
ranging 1040% ethanol– water (v/v). For example, linalool cor-
responding thresholds are 5, 50, 1000 µgL
lfor water, 10 and
40% ethanol/water (v/v). Odour activity value is a measure of the
importance of a specific compound to the odour.36 It is calculated
as the ratio between the concentration of the individual substance
and its threshold concentration. Aroma extract dilution analysis
can also be used to identify the most important aroma compounds
and determine the highest flavour dilution factor.37
More than 500 substances have been detected in spirits14 that
belong to a large number of chemical classes, such as terpenes,
alcohols, esters, aldeydes, ketones, acids and phenols. However,
only a few of these substances are important for its contribution
to the brandy sensory characteristics. Quite recently, the use of
chemical markers has been employed for tracking the sensory
contribution of each the three post-fermentation stages of a
Chilean spirit. Pe ˜
na y Lillo et al.,4using multivariable statistical
methods and applying heuristics for matching the sensory and
chemical differentiation of brandy samples, managed to determine
the main sensory contribution of blended and aged wine distillates
by following the concentration of just one corresponding chemical
marker.
Terpenes
Terpenes are mainly present in the grape skins. Their concentration
is particularly high in Muscat grape varieties. About 40 terpene
compounds have been identified in grapes. Some of the
monoterpene alcohols, which posse a characteristic floral aroma,
are among the most odoriferous, especially linalool, α-terpineol,
nerol, geraniol, citronellol and hotrienol. The olfactory perception
thresholds of these compounds are rather low (a few hundred
micrograms per litre). In Muscat wines, terpenes are found either
free or bound to sugars as glycosides. The latter are also called
aroma precursors, as they are unable to express their aromatic
character. However, upon hydrolysation, which occurs during
distillation, these precursors liberate free terpenes. High distillation
temperature and low pH may, however, oxidise terpenes, leading
to less positive or negative odorant forms.5
Alcohols
Ethanol (ethyl alcohol) is the most abundant compound in wine,
after water. In wine it is produced by the alcoholic fermentation
of glucose and fructose. Under standard fermentation conditions
ethanol may accumulate up to 14% (v/v). The ethanol content of
the wine spirit is habitually 70% (v/v) with a recovery of 99%, while
brandy’s ethanol content, after addition of pure water, is about
40% (v/v).
The accurate and rapid determination of ethanol in alcoholic
beverages is very important for economic reasons. The techniques
used for this purpose can be grouped into chemical, physical,
enzymatic and instrumental physico-chemical methods. A
reagentless amperometric biosensor, which is sensitive to ethanol,
was developed by Santos et al.38 This sensor was comprised of a
carbon paste electrode modified with alcohol dehydrogenase,
nicotinamide adenine dinucleotide co-factor and Meldola’s
blue adsorbed on silica gel coated with niobium oxide. The
proposed biosensor presented good sensitivity allowing ethanol
quantification at levels down to 8.0 ×106mol Ll. Another
method based on infrared spectrophotometry was developed for
the determination of ethanol in alcoholic beverages39 where
satisfactory results were obtained with the help of Glenn’s
orthogonal and first-derivative functions to correct for water
absorption. In addition, a spectrophotometric procedure was
developed40 for the ethanol determination in alcoholic beverages
by employing a flow system based on a multi-commutation and
binary sampling approach. The method was based on ethanol
oxidation by dichromate in sulfuric acid medium and detection by
spectrophotometry.
Methanol (methyl alcohol) is not produced by alcoholic
fermentation. It is formed exclusively from the enzymatic
hydrolysis of the methoxyl groups of pectins during fermentation.
It is always present in very small quantities, 4060 mg Llin
wine. However, in distillates and brandy it is found in higher
concentrations 0.300.70 g L1of pure alcohol with a recovery
of 90%. Its taste is similar to ethanol and it does not affect the
organoleptic quality of the spirits. However, it affects the safety of
brandy because its toxicity is well known.41 Following ingestion, it
oxidises to formaldehyde and formic acid, both of which are toxic
to the central nervous system. Formaldehyde causes deterioration
of the optical nerve, leading to blindness.42 European Union
legislation requires a limit lower than 2.0 g L1of pure alcohol.
Methanol is reduced during ageing in casks.43
Fermentation alcohols with more than two carbon atoms are
known as higher or fusel alcohols. They are synthesised by
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yeasts during fermentation, either directly from sugars or from
grape amino acids via the Ehrlich reaction. In wine, the higher
alcohol content remains almost unaffected before distillation.
Quantitatively, the most important higher alcohols are the straight-
chain alcohols: 1-propanol, isobutyl alcohol (methyl-2-propanol-1)
and amyl alcohols (a mixture of 2-methyl-1-butanol and 3-methyl-
1-butanol). Most straight-chain alcohols and their esters have a
strong pungent smell. At low concentrations, they contribute to
the aromatic complexity but at higher levels are characterised by
penetrating odours which mask the aromatic finesse. In distilled
spirits, such as brandies, rum and whisky, fusel alcohols provide
most of their common aromatic character.
They reach concentrations in the range of 150550 mg Llin
wine and 2.55.0 g L1of pure alcohol in distillates. Recovery is
about 90% with the exception of 2-phenyl-ethanol which is 10%
recovered.
The herbaceous odour of brandies is due to grape-derived
carbonyl compounds with six carbon atoms. Unripe grapes and
continuous presses may induce herbaceous tastes by liberating
compounds, such as hexanols (hexanol-1 and hexanol-2) and
hexenols (cis-3-hexene-1-ol, trans-2-hexen-1-ol, cis-2-hexen-1-ol).
1-Octen-3-ol is characterised by a mushroom odour and it is
produced in grapes infected by Botrytis cinerea.42
Volatile acids
Acetic acid is the main volatile acid and contributes greatly
to the volatile acidity. It has a vinegar-like intense odour and
its concentration is significantly increased during wine ageing.
Although it commonly occurs in wine, it typically occurs at
detectable levels only in wines spoiled by acetic acid. During wine
maturation in barrels, a small quantity of acetic acid, however, can
be produced from ethanol oxidation or it can be extracted from
wood hemicelluloses. In wine, it is found in concentrations ranging
from 300 to 700 mg Ll, while in distillates the concentration ranges
from 0.20 to 1.0 g L1of pure alcohol. Recovery is as low as 2–5%
due to the removal of the distillation ‘heads’. However, distillates
produced by continuous distillation may contain higher amounts
of acetic acid due to the absence of the removal of the distillation
heads.
Other carboxylic acids, such as propionic acid and butyric acids
may also be present and they are also associated with bacterial
activity. Butyric acid is characterised by unpleasant buttery and
cheesy aromas and its concentration is increased during ageing.
Hexanoic, octanoic, decanoic, dodecanoic, myristic (14 carbon
atoms), palmitic (16 carbon atoms), and stearic (18 carbon atoms)
acids are formed by yeasts.
Ethyl esters
Esters are condensation products of the carboxyl group of an
organic acid and the hydroxyl group of an alcohol or a phenol.
Esters are produced by yeasts after cell division has ceased.
They can also be present in grapes, but their amount and
sensory importance are often negligible. Esters are present in
fresh brandies and since they have fruity aspects, they have an
important contribution to the development of their aroma. Over
160 esters have been identified in wines and most of them are also
present in brandies. Recovery varies from 40 to 60% depending
on the distillation technique.
Of the monocarboxylic acid esters, the most important are those
based on ethanol and saturated carboxylic acids, such as hexanoic
(caproic), octanoic (caprylic) and decanoic (capric) acids. These
are often considered to give wine much of its vinous fragrance.
The ethyl ester content of brandies increases during ageing, as a
consequence of the slow esterification of different organic acids
with ethanol. Preserving wines before distillation in the presence
of lees has been connected with increased content of ethyl esters,
since they are generally retained within yeast cells, rather than
being released into the fermenting must during fermentation.
Ithas been found3that there areabout four times less ethylesters
of fatty acids with 8, 10 and 12 carbon atoms in Armagnac than
in Cognac. Some brandies contain noticeably lower quantities of
esters than others. This can be attributed to the utilisation of ‘wine
distillate’, which results in poorer distillates concerning volatile
substances.
Ethyl butyrate concentration increases with ageing, with the
absence of antioxidant and antimicrobial agents, and mainly with
increased temperature. In general, wines pressed by continuous
presses contain higher amounts of ethyl esters of long chain fatty
acids (1418), due to the fact that they contain relatively lower
oxygen which affects their synthesis by yeasts.44 Distillates of wines
which have remained in contact with lees contain greater amounts
of ethyl decanoate and ethyl laurate.9Recent research has shown
that some brandies contain naturally rare ethyl esters, which may
have some impact on their aroma. Such compounds are ethyl 2-, 3-
and 4-methylpentanoate, and ethyl cyclohexanoate, which exhibit
pleasant strawberryliquorices-like odours.45 As brandy matures,
ethyl esters become less flavour-active,46 due to an increase in their
solubility in aqueous ethanol by the wood-extracted materials.
The most prevalent ester in wine is ethyl acetate. A small quantity
is produced by yeasts during fermentation, but it is mainly formed
by the activity of the aerobic acetic bacteria. Wines normally
contain below 40 to 120 mg Ll, while distillates and brandies
contain about 0.4 to 0.8 g Llof pure alcohol. Ethyl acetate has
a recovery of 100% in continuous distillation and 60% in batch
distillation.
Higher alcohol acetates
The formation of esters between acetic acid and higher alcohols is
also important since they may provide a fruity character. For
example, isoamyl acetate, which has a characteristic banana
odour, positively influences brandy’s aroma. Low fermentation
temperatures favour synthesis of fruity esters, such as isoamyl,
isobutyl and hexyl acetates, while higher temperatures favour the
production of higher molecular weight esters. Both low SO2levels
and juice clarification favour ester synthesis and retention. The
absence of oxygen during yeast fermentation enhances further
ester formation.47
Ester synthesis as well hydrolytic breakdown continue non-
enzymatically during ageing based on the chemical composition
and storage conditions of the brandy.
Aldehydes and ketones
Acetaldehyde (ethanal) is the major aldehyde found in wine. It
is one of the early metabolic by-products of yeast fermentation.
More acetaldehyde is produced through autoxidation of ethanol.
An important quantity is bound to sulfur dioxide in cases where
it is has been added to the base wine. The toxicity associated
with acetaldeyde is well known and its presence in the alcoholic
beverages is quite often related to nausea and vomiting. In
distillates and brandies it is found in concentrations ranging
from 0.20 to 0.25 g L1of pure alcohol.
Other aldehydes which may be found in brandies are
formaldeyde, 5-hydroxymethylfyrfural, acrolein, propionaldehyde,
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butyraldeyde, benzaldehyde, isovaleraldeyde and n-valeraldeyde.
The aldehydic content of brandy can be analysed by reversed-
phase HPLC.48
Isobutanal at concentrations higher than 25 mg Llcould give
a herbaceous character to the brandy. However, during ageing its
content declines due to acetylysation and selective evaporation.
trans-Nonenal is characterised by a paper-like sense, while octanal
contributes to the aroma complexity by adding an orange
flavour. Although concentration of both the above aldehydes
is increased during ageing, it generally remains below the
perception threshold. However, significant statistical correlations
have been obtained among the herbaceous odour and aldehyde
concentration.49
β-Damascenone is a isoprenoid ketone which is present in
grapes. Since it is a highly odoriferous compound with a powerful
and pleasant fragrance, it is an important compound in the
perfume and flavouring industries. As it has a very low sensory
threshold, β-damascenone is considered to be a key odour
compound in brandy, imparting a ‘stewed apple’, ‘fruityflowery’
and honey-like character.50 Diacetyl (2,3-dioxobutane), is a ketone
produced during wine fermentation through oxidation of acetoin,
a degradation product of citric acid.51 It has an important sensory
influence on brandy since its odour is characterised as sweet,
buttery or butterscotch-like.
Sulfur derivatives
Brandy may contain extremely low concentrations of different
unpleasant (rotten eggs, garlic) volatile sulfur compounds, such
as hydrogen sulfide, carbonyl sulfide, sulfur dioxide, thiols,
sulfides, polysulfides and thiosterols. The determination of these
compounds in wines and spirits is difficult because of their volatility
and their very low concentrations, which require the use of highly
sensitive detectors. Among the different analytical techniques,
gas chromatographic separation coupled with sulfur-specific
detection, namely flame photometric detection, is the most widely
used method. Nedjma and Maujean52 used a static headspace
technique and a chemiluminescence detector. Counter-current
supercritical fluid extraction could also be used as it permits
maximum extraction of aroma compounds in brandy.
Ethyl carbamate
Ethyl carbamate is a potential carcinogenic compound and its
presence is strictly monitored in wines and spirits. Yeasts may be
involved in ethyl carbamate synthesis through the production of
carbamyl phosphate and by the synthesis and degradation of urea.
The official determination method of ethyl carbamate in alcoholic
beverages is GC-MS. However, other methods such as HPLC53 and
HPLC with post-column fluorescence derivatisation have also been
employed.54
Organo-tin compounds
Organo-tin compounds are widely used in agriculture and industry.
They can also be present in brandies and wines. Because of
their high toxicity, even at very low concentrations, sensitive and
selectiveanalytical procedures must beemployed for their analysis.
Recently, these compounds were detected in wine samples, with
concentrations varying55 from 50 to 80 000 ng Ll. Heroult et al.55
developed an analytical method for determination of ethylated
organo-tins in brandies based on solid-phase microextraction.
A tetrahydro-β-carboline (1-methyl-1,2,3,4-tetrahydro-β-carbo
line-3-carboxylic acid ethyl ester) was identified56 in alcoholic
beverages in amounts ranging from undetectable levels to 534
mg Ll. RP-HPLC with fluorescence detection and GC-MS were
used for its identification.
Trichloroanisole
Fortunately, cork taint in wines is very rare. It produces a very
unpleasant, putrid smell that causes wine quality to deteriorate.
Their origins are certainly related to wine corks, but it may appear
also in brandies. In brandy, 2,4,6-trichloroanisole was described as
possessing a walnut-like aroma. In brandy, 2,4,6-trichloroanisole
can be perceptible 530 min after consumption.57
Furfural and furanic compounds
Another aldehyde having a sensory impact of ‘baked’ in brandy
is furfural (0.582.5 mg Llof pure alcohol). Its synthesis involves
sugar oxidation and it is activated by heat. It is mainly produced
during distillation from the remaining pentose content of the lees
and consequently it is highly influenced by the distillation system
employed. For this reason, the concentration of furfural in brandy
shows high fluctuation. Furfural and its derivatives may also derive
from both the wooden cask and the possible addition of caramel.
Double distillation enhances the amount of all furanic species.
Thus, Cognac can be differentiated from Armagnac, since Cognac
contains higher contents of furan derivatives.33
Non-volatile substances in brandy
Total acidity
Total acidity in brandies is initially due to the presence of volatile
acids, such as acetic acid. Acetic acid content increases during
ageing by oxidation of ethyl alcohol. In addition, total acidity
progressively increases due to the extraction of phenols from oak
casks. Phenols are weak acids that gradually create a fixed acidity.
New brandies have pH values between 4 and 5, while during
maturation pH falls to 3.5.
Metal content
Although wine contains different metals, they are not volatile and
therefore they cannot be found in the distillates. Brandy acquires
its metallic content by contact with different metals of stills during
distillation.
Aluminium is widespread throughout nature – in air, water and
plants and consequently in all the food chain. Also, packing
materials and containers may contaminate alcoholic beverages.
A reliable and rapid method for the determination of aluminium
in alcoholic beverages by graphite furnace is atomic absorption
spectrometry.58 The mean aluminium concentrations in alcoholic
beverages ranged from 15.7 to 739.6 mg Ll.
The cadmium content of alcoholic beverages was measured by
electrothermal atomisationatomic absorption spectrometry.59
The mean values measured ranged from undetectable levels to
11.52 µgL
l. The wide variability of the results emphasised the
multiplicity of factors that can influence the presence of cadmium
in these products.
Calcium, copper, iron, magnesium, manganese and zinc can be
measured by flame atomic absorption spectrometry in brandies.
Potassium and sodium content can be determined by atomic
emission spectrometry, while aluminium, cadmium and lead by
graphite furnace atomic absorption spectrometry.60
Copper is a very important trace element due to its heat
conducting and chemical properties. Most of the copper found in
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wines originates from sprays based on the disinfectant properties
of copper sulfate, used to treat vines for mildew. Copper could
combine with caprylic, caproic and lauric fatty acids, whose
odour resembles that of cheese, as well as with long-chain fatty
acids which could produce insoluble soaps. As far as distillation
is concerned, its presence is connected with higher quality
distillates. Distillation in stainless-steel distillers results in poor-
quality brandies. The process can be improved by the addition of
turnings of copper or copper sulfate.3
Caramel
The addition of caramel is quite common in the production of
aged spirit beverages since it gives them an amber coloration
that is attractive to the consumer. The chemical composition
of caramel is complex, due to the large number of substances
produced as a result of pyrolysis of carbohydrates, such as sucrose,
glucose or starch. However, furanic compounds are also present,
such as furfural or 5-hydroxylmethyl furfural, of which the latter
is found in much higher concentrations. In cases where caramel
colour has been added to brandies, it influences the furfural/5-
hydroxylmethyl furfural ratio, as it is higher than 1 in brandies
without caramel and lower than 1 in those with the addition of
caramel.61
The colour characteristics of a brandy can be estimated by
calculating a trichromatic value at wavelengths between 400 and
700 nm every 5 nm.32 A simplified method to calculate colour
coordinates by measuring only three wavelengths was proposed
by Ayala et al.62
Maturation in casks
Oak wood consists of 4045% cellulose, 20–25% hemi-cellulose,
2530% lignin and 8–15% tannins. These components are best
extracted by wine spirits with an ethanol concentration of 55%
(v/v).31 The natural colour of the brandy is due to the presence
of tannins. The phenolic composition of distillates that have been
aged in barrels can be analysed by HPLC.63
Volatile compounds from casks
Volatile compounds extracted from the barrel wood are mainly
furanic and phenolic compounds. Concentration of furanic
compounds, such as furfuryl ethyl ether, furfural, 2-acetylfuran and
5-methylfurfural, varies according to the type of cask and ageing
time. Furanic aldehydes derive from the thermal degradation of
wood polysaccharides of wooden casks.
Eugenol, cis-β-methyl-c-octalactone, furfural, 4-hydroxy-2-
butenoic acid lactone, hexanoic acid and guaiacol seemed to
be important compounds, which could be related with the wood
origin. The toasting process can modify strongly the volatile
composition of the different types of wood, particularly the levels of
furanic aldehydes (furfural, 5-methylfurfural with toasted almond
aromas, 5-hydroxylmethyl furfural), volatile phenols (syringol
and 4-allyl-syringol), propanoic acid, 4-hydroxy-2-butenoic acid
lactone and vanillin.64 When wood is not toasted, the extraction
during ageing is limited. After three consecutive uses (3 years) the
wood will no longer liberate fatty acids, coniferaldeyde, furfural, 5-
methylfurfural and 5-hydroxymethyl-furfural into the wine spirits.
However, it is still an important source (3050%) of polyphenols,
ellagic acid, gallic acid, vanilline, methyl-octalactone and eugenol.
During the first use, the barrel wood contributes mainly to the
toast aroma of spirits, while during the second and third it offers
more vanilla flavour.65
The first year of ageing of Cognac and Armagnac takes place
in new oak casks, while after that period they may be placed in
used casks. Sherry brandies (brandies de Jerez) are aged in casks
of American oak (Quercus alba), which previously contained sherry
wine. This prior procedure is known as the ‘wining’ of the casks.
The characteristics of each brandy de Jerez will vary according to
the type of sherry which the oak-wood casks previously contained.
Brandies de Jerez age according to the traditional dynamic system
known as ‘Soleras y Criaderas’. In this system, only a proportion
of the brandy contained in the oldest barrel (situated at ground
level, hence the name: solera) is drawn off for bottling. Then that
barrel is refilled from the next oldest cask (the first criadera) and
that, in turn, is refilled from the third oldest, and so on to the
youngest cask, which contains the newly distilled product. The
quantities of the younger product transferred in this way mix
with the older product in the corresponding barrel, thus acquiring
the desirable characteristics.30 Phenolic and furanic content of
brandies de Jerez, increases considerably during ageing.24
Most casks are made by oak wood and rarely by chestnut
wood. Caldeira et al.64 confirmed the strong influence of the barrel
toasting degree on the sensory profile of the aged brandies. The
brandies that had been aged in strong toasted chestnut barrels
presented sensory properties more closely related to the older
brandies than the brandies aged in medium or light toasting
barrels. The cis-β-methyl-γ-octalactone content of the brandies is
an important chemical marker to distinguish chestnut from oak
wood.66 Brandies matured in barrels made with American white
oak contained higher amounts of (3S,4S)-oak lactone than those
matured in barrels made with Quercus robur from Europe.67
In spite of their wide acceptance, the use of wooden barrels
is prone to some problems, such as the high cost and the
difficulty of their handling. Therefore, recently, the use of wood
fragments in order to promote an accelerated ageing process
became an interesting economic alternative to the wooden
barrels. Alternative wood ageing systems (staves and tablets)
were compared66 with wooden barrels after an ageing period
of 6 months. The brandies aged in wooden barrels contained
the highest levels of several ethyl esters, acids, furanic aldehydes
and the lowest levels of volatile phenols. Regarding eugenol
and vanillin levels, the lowest values were found in the brandies
aged with tablets. The smoky and toasted odour notes associated
with some volatile phenols could explain the higher toasted
notes reported for the brandies aged with tablets. In fact, a
positive linear correlation was found between the levels of
guaiacol, 4-methylguaiacol and syringol and the toasted attribute.
Considering the overall quality of the brandies, the results obtained
suggested the use of wood fragments to be an interesting
alternative technology. On the other hand, the chemical analysis
of the brandies showed the possibility of discriminating the ageing
technologies based on odorant compound levels.
Non-volatile compounds from casks
The ageing of spirits in oak barrels is a complex process. Direct
extraction of wood components or degradation products of
macromolecules of the wood may occur, as well as reactions
between the components of the distillate itself and/or those
originating from the oak wood (polymerisations, esterifications,
acetylysations, and hydrolysis), in addition to major oxidation
processes. Apart from ellagitannins, oak releases a certain number
of other compounds into brandies, mainly lignins. Depending
on conditions, oak may also release polysaccharides, mostly
consisting of hemicelluloses, that contribute to spirit flavour.
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Liquid chromatography with diode array detection and liquid
chromatographymass spectrometry has been used for their
analysis. Capillary electrophoresis is a simple and useful method
which has been employed for the analysis of tannins and other
polyphenolic compounds of brandies.68
Antioxidant activities
Brandies contain polyphenols which are well-known antioxidants
having a protective effect on human health. They acquire their
polyphenolic content and thus their antioxidant activity during
ageing through contact with the barrel wood.
A significant correlation between the antioxidant activity and
the total polyphenolic content of the spirits has been found.69
In respect of the compounds considered individually, each
polyphenol had a different antioxidant power depending on its
chemical structure. The compounds which were present in greater
concentrations were not necessarily those better correlated with
the antioxidant power of the samples. When brandies had been
in contact with wood, a significant amount of polyphenols was
extracted resulting in an important contribution to the antioxidant
power.
Schwarz et al.70 studied the antioxidant activity of commercial
sherry brandies obtained from an experimental ageing system
(Solera, Solera Reserva and Solera Gran Reserva). They concluded
that this parameter was correlated with the total phenolic content.
The results also suggested that addition of caramel may also
contribute to the antioxidant activity of the brandies. It was also
found that Solera Gran Reserva samples showed the highest
antioxidant activity of all the products studied.
Sensory evaluation
Sensory evaluation of brandy is similar to wine tasting since it
includes colour, smell, mouth feel and after-taste examination.
The main difference is that brandy contains lower quantities of
acids and a much higher quantity of ethyl alcohol that provides an
alcohol burning sensation known as ‘rime’.
S´
egur and Chassin71 proposed the use of description forms
in order to characterise Armagnac by sensory evaluation. The
first form was related with the acceptance or not of the product
based on the detection of sulfur, alcohol burning, butterputrid,
wineyvinous, bitter and drying aspects. They also proposed a
second form of a more detailed examination of the final product
which included visual, nose and mouth evaluation of selected
sensory attributes.
A special form is used by the Office International du Vin
(O.I.V.) for the evaluation of the international spirituous beverages
of vitivinicultural origin (www.oiv.int). In more detail, visual
evaluation concerns limpidity and colour. Nose examination
involves typicality, quality and positive aromatic intensity. Finally,
mouth evaluation focusses on typicality, quality and harmonious
persistence. It is difficult to define precisely these sensory attributes
and correlate them with brandy chemical composition and sensory
evaluation data. It depends on the personal evaluation abilities of
the tasters since it is, to some extent, a subjective judgment.
Thus, in recent years research has focused on possible
correlations between the sensory data and the results of the
chemical analyses. Precise sensory measurements of both odour
(orthonasal) and aroma (retronasal olfactory perception) are time
and resource consuming. An improved olfactory tasting procedure
was developed by Pena y Lillo et al.72 based on the comparison
of odour and aroma profiles of Pisco spirits and aiming at
predicting the aroma from the odour profile, shortening thus
the evaluation time. A second aim was the assessment of the
sensory contribution of each post-fermentation production stage
of Muscat wine distillates by the use of chemical markers. They
formed sample clusters of sensory and chemical data employing
principal component analysis and revealed the potential chemical
markers. The chemical markers which were characteristic of the
‘head’ fraction were ethyl hexanoate, ethyl octanoate and ethyl
decanoate. The possible chemical markers of the first part of the
‘heart’, included linalool, ethyl hexanoate, ethyl octanoate, and
ethyl decanoate while of the second part 2-phenylethanol, ethyl
lactate and decanoic acid. Oak ageing was correlated with eugenol
and whisky lactones, while 5-hydroxy-methyl-2-furfural accounted
for added caramel.
Ferrari et al.73 used gas chromatographyolfactometry to
identify odorant compounds responsible for the typical sensory
descriptors attributed to freshly distilled Cognac spirits, not
matured in barrels. They demonstrated that many odorant
molecules were already present in freshly distilled Cognac,
thereby providing the spirit with its specific aroma. Among
more than 150 organic compounds identified in Cognacs not
aged in wooden casks, only 34 were responsible for odours. The
‘butter’ descriptor was explained by the presence of diacetyl,
the ‘hay’ descriptor by nerolidol, the ‘grass’ descriptor mainly by
(Z)-3-hexen-1-ol, the ‘pear’ and ‘banana’ descriptors by 2- and
3-methylbutyl acetates, the ‘rose’ descriptor by 2-phenylethyl
acetate and the ‘lime tree’ descriptor by linalool. Moreover, gas
chromatographyolfactometry followed by GC-MS analysis was
used74 to identify and characterise aroma compounds responsible
for distinctive odours of brandies produced in Slovakia. It
was found that the presence of olfactive zones described by
olfactory attributes, such as fruity (including vegetable), floral and
herbal depended on maturation time. Caldeira et al.66 studied
odorant compounds in different aged brandies from Lourinh˜
a.
These compounds presented important correlations with several
olfactory attributes, such as vanilla, woody, spicy, burned/toasted,
dried fruits, smoke, fruity, green and tails.
Authentication
GC, GC-MS and ultravioletvisible spectrophotometry have been
employed for identifying the adulteration of strong alcoholic
beverages including brandies. Multi-component analysis of spirits
can reveal the replacement of spirit with alcohol produced from
non-grape raw materials, determine whether the spirit was in
contact with oak wood and how long was the duration of
its ageing, and detect the acceleration of the ageing process
by adding certain ingredients.75 Lehtonen et al.76 developed
a method based on the determination of higher fermentation
alcohols (propanol, isobutanol, 2-methyl-1-butanol, 3-methyl-1-
butanol), ethyl acetate, pH and UVvisible absorbance to identify
the types and/or brands of matured distilled beverages.
A common adulteration is the addition of inappropriate (for
food purposes) ethanol, such as synthetic ethyl alcohol produced
by the hydration of ethylene or of industrial ethyl alcohol prepared
from wood raw materials. It is possible to determine whether
ethanol derives from fermentation or it has been synthesised by
using a set of characteristic impurity markers of alcoholic nature,
which are present in a certain ratio and can be determined by
GC or GC-MS analysis. Acetone, 2-butanol, crotonaldehyde and
some other impurity substances typical of synthetic alcohol and
atypical of alcohols produced by fermentation can be used as such
markers. Furthermore, vanillin and syringaldehyde could be used
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as age markers. The dilution of Cognac with rectified alcohol or a
wateralcohol mixture can also be detected since it results in a
proportional decrease in the concentrations of all components.75
Fourier transform infrared spectroscopy was employed77 for the
differentiation and classification of brandies during their ageing
process, as well as for the characterisation and differentiation of
the origin of distilled drinks from several producing countries.
An alcoholic beverage is a complex mixture consisting of a large
variety of substances with different spectroscopic characteristics.
A new method78 was developed to discriminate brandies and
wine distillates using differences in their front face fluorescence
spectra and multivariate data analysis. Owing to the low price
of the wine distillates, they may be used for the counterfeiting
brandies.
A novel method was also proposed79 to determine adulteration
of alcoholic beverages based on the measurement of the
Schlieren effect using an automated flow injection analysis system
with photometric detection. The flow system presented limited
mixing conditions which made possible to create gradients of
refractive index in the injected sample zone. These gradients
were reproducible, characteristic of each alcoholic beverage and
underwent specific modifications when adulterations with water
or ethanol were imposed. Finally, site-specific natural isotope
fractionationnuclear magnetic resonance analysis, based on the
different natural distributions of the deuterium isotope in ethanol
content of samples of various origins, contributed significantly in
the authentication of brandies.80
CONCLUSIONS
Brandy production from grapes constitutes a traditional industry
that does not pursue productivity innovations. Current research is
oriented mainly in exploring analytical methods and determining
the various parameters that may affect brandy quality, such as
vine cultivation techniques, grape quality, detection of pesticides
applied to the vines, fermentation conditions, microorganisms of
alcoholic fermentation, and preservation of wines until distillation.
Research is also focussed on estimation of the appropriate
separation point of the fractions during distillation, according
to their composition in order to improve quality and to provide
a distinctive aroma and a smooth taste to the final product. In
addition, interesting research areas include the investigation of
the shape and the material composition of the distillation units, the
effect of oxidation and ageing on the composition of spirits aged
in wooden casks and the mixing of different batches to improve
quality. The establishment of criteria for the qualitative ranking of
brandy based on sensory evaluation, as well as the differences in
the composition of brandies from different varieties or different
areas are also of interest. The existing literature concerning brandy
includes studies focusing on the estimation and identification of
the quality of brandy based on its detailed chemical composition.
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... Grape acids, predominantly tartaric acid, act as a natural preservative, which is necessary since sulphur dioxide should not be added to musts and wines during wine spirit production. Musts and wines are not treated with sulphur dioxide since, later, it could be transferred into the distillate and thus decrease its quality by neutralising the aromatic perception [12,13]. Grape with a fruit-associated neutral aroma is favoured for the production of wine spirits since the utilisation of such grapes ensures cost-effectiveness in the production of wine spirits. ...
... 1-octen-3-ol is characterised by a mushroom odour, and it is found in grapes infected by Botrytis cinerea. The β-damascenone is a norisoprenoide that is naturally present in grapes, and it is a highly odoriferous compound with a powerful and pleasant fragrance providing a fruity-flowery and honey-like character [13]. ...
... Its smell and taste are similar to ethanol, and since it is present in low concentrations, it does not affect the sensory quality of the spirit. However, it affects spirit safety since its toxicity is well known [13]. Hundreds of volatile compounds have been identified in grape brandies; however, esters, as we said before, are one of the most important compounds that contribute to aroma. ...
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... Grape spirit is produced by batch distillation in small pot stills or by continuous distillation in column-still distills (Tsakiris et al., 2016). Although wine contains different metals, these metals are not volatile and, therefore, are not found in the distillates. ...
... As far as distillation is concerned, the presence of copper is connected with higher-quality distillates. Accordingly, distillation in stainless steel distillers results in poorer-quality brandies, the quality which can be improved by the addition of exogenous copper or copper sulfate (Tsakiris et al., 2016). ...
... Due to its own reactivity, the double bond is a weak point in the carbon chain, and certain reactions, such as oxidation reactions, can lead to a rupture between two double bonded carbons. The linalool concentration presented in freshly distilled wine spirits supposed to be consumed over time, as there is no way to form it in the reaction mixture, given that primarily sources of terpenes are the grapes skins and pulp [35,37,38]. Our findings for this compound might suggest further studies to determine whether it can be used as a marker of the authenticity of the wine distillate, as well as of its ageing time, since the longer it ages, the less linalool in its free state should be present. ...
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... This concentration was three times the maximum legal limit (5 mg 100 mL -1 a.a.). The pathways for the formation of furfural and HMF in cachaça are associated with the burning of sugarcane used as raw material, in which the pentoses and hexoses are degraded, or by the presence of sugar and yeast residues and overheating during distillation (Masson, et al. 2007;Cardoso, 2013;Tsakiris, et al. 2016). ...
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Grape brandy is a spirit drink produced by wine distillation and is matured in wooden casks. According to legislation, it can be characterized by the geographical area where the grapes were produced, the grape variety used and the selected distillation and aging techniques. Distillation increases ethanol concentration and aromatic constituents which are already present in grapes or are developed during fermentation and distillation. During maturation in wooden casks, compounds that contribute to the aroma and taste are extracted from the wood. Hence the spirit, acquires the desired soften mouth feel, aromatic complexity and overall quality. Different methods of analysis are used in order to pursuit this process by analyzing volatile and non volatile substances and correlate composition with quality. Analysis can also be useful in identification of brandy safety, potential adulterations, provenance and differentiation from other spirits drinks.