When wine has a
thirst for research
September 2013
Table of contents
2
News Office I +33 1 42 75 91 69 I [email protected]
4
Tasting as the centre of attention
6
It’s in the bouquet!
7
Wines of every hue
8
AOC wines, a family resemblance
10
Spotlight on prices
11
Grapes that are good enough to eat
13
Innovations from harvest to the bottle
16
These yeasts that can make good wine
18
New winemaking practices
22
Climate change: which wines for tomorrow?
24
It’s trendy!
When wine has a thirst for research
Red, white, rosé... sweet, dry, sparkling... since man first sought to master the production and storage of wine, science has played a central role. How does the taste
of a wine develop? Where do its aromas come from? By looking at vines, their
genomes, varieties, grapes, bacteria or yeasts, INRA scientists are uncovering the
secrets of this extraordinarily complex mixture, in order to improve its quality.
Although they are constantly enriching their knowledge of the chemistry of wine,
INRA scientists have also been the inventors of technological processes that are
already disseminated throughout the world. The removal of alcohol, the Flash
détente process, aroma capture, tangential microfiltration, etc., are all innovations
that can optimise the production, stabilisation and packaging of wine. But INRA is
also in the forefront when it comes to understanding the links between a wine and
its terroir, and proposing scenarios for adaptation to climate change. Today, one of
its priority research areas is to ensure a transition towards viticulture that uses the
fewest possible inputs and produces wine containing a minimum of additives.
France is the leading wine producer in the world, and reputed for this symbol of gastronomy and the art of living. Wine is the most widely consumed alcoholic drink in
France. INRA conducts its research on wine and oenology in its own vineyards, on its
experimental plots or in laboratories based in the heart of French wine regions, as
close as possible to actors in this industry. From the perception of wine to its production, from our glasses to the grape, this document is devoted to all aspects of wine.
And you can read it to your heart’s content!
News Office I +33 1 42 75 91 69 I [email protected]
3
Tasting as the centre
of attention
Robe, colour, tannin, structure, body, astringency... the vocabulary used to describe
wine is particularly rich because all the senses become involved when tasting it.
Although colour intensity, clarity and brightness all contribute to a wine’s robe, its
body provides fullness and density in the mouth. But what can we perceive within
this complex mixture? And how do we perceive it?
© Fotolia
Black glasses for sensory analysis.
© Inra - Yves Cadot
1 Appearance, odour, taste, texture or consistency are the
organoleptic characteristics of a food or drink, as they
reflect everything that is likely to act on the senses.
4
From chemistry to subjectivity
Examining vintages, defining organoleptic characteristics 1, measuring the consequences of a process change, optimising
assemblies, forming a tasting panel and measuring the impact of a packaging system... Several teams at INRA devote their
efforts to sensory analysis, particularly with respect to wine. Thanks to panels of people who are selected and trained in
tasting, their research enables a clearer definition of the sensory profiles of wines; it also enables a better understanding
of the mechanisms related to pleasure or rejection, which vary from one individual to another and contribute to defining
the quality of a product. Since the 1970s, specialists have sought to identify the aromas in wine, their elemental flavours
and their molecular origins. But the use of analogies (fruits, flowers, spices, etc.) still remains necessary.
Thus flavour descriptors such as ”banana“, ”floral“ or ”fruity“ indicate butyl acetate and ”apricot“ or ”honey“ suggest
ethyl beta-phenylacetate, while ”truffle“ tends to correspond to dimethyl sulphide. Although describing the nose of
a wine is often at the centre of a tasting, our senses still tend to privilege sight. One subterfuge consists in colouring
white wine as red, so that the tasters start using a vocabulary associated with red wines (red fruits), even though they
should be using descriptors for a white wine (honey, apricot, apple, banana)! Wine tasting thus induces activation of
the visual cortex. It is to iron out this bias that black-tinted glasses are often used for sensory analyses.
Ultimately, it is the consumer who has the last word, which is highly subjective.
News Office I +33 1 42 75 91 69 I [email protected]
The mouth, nose or brain... wine for all the senses
Hundreds of chemical compounds have been identified in grapes and wine. However, only a tiny number are responsible for
a wine’s bouquet, or in other words all its aromatic components. Recent studies performed by INRA have shown that odorant
substances arising from oak barrels, even at very low concentrations (sometimes below the threshold of detection), may have
an effect on a wine’s bouquet. Another experiment: researchers presented 30 volunteers with mixtures of one woody odorant
substance and another fruity substance, either directly via the nose or through the mouth (the retronasal route). The first
observation was that depending on whether the odorant compounds entered via the nose or mouth, there were differences
in perception. For example, the scientists showed that the perception of a fruity odour was enhanced when the woody
odour in the mixture was present, even at a barely perceptible level. By contrast, when the woody odour was more intense,
perception of the fruity note diminished. Such sensory effects result from perceptive interactions during the integration of
olfactory information by the brain, which occurs as soon as a mixture of odorant substances reaches the olfactory mucosa.
A considerable number of odorant compounds have been identified in wines and new ones
are still being discovered. Human perception of them is not solely the result of their individual
concentrations but of their aromatic power and combinations. For this reason, human ”sensors“
are the only ones capable of integrating all perceptions, translating them into descriptors and
then quantifying them.
Fruity notes that are
difficult to perceive
Red wines from the Bordeaux region are well known for their fruity notes, evocative of red
or black fruits. However, no ”key“ compound at the origin of this fruity descriptor has been
identified (in other words, at a level markedly above its threshold of perception). The source
of these fruity nuances has been the subject of several studies. Thus numerous compounds
are known to markedly influence the fruity expression of red wines, even though they are
present in quantities far below their level of perception. One example is ethyl leucate, which
has proved to be a remarkable enhancer of black fruit or fresh fruit notes. Inversely, other
compounds (acetoin, acetic acid, γ-butyrolactone) diminish the aromatic intensity of a wine
and its fresh, fruity nature. Obtained by a Université Bordeaux Segalen and INRA team,
these results highlight how difficult it is to precisely determine the bouquet of wines. They
also call into question the traditional approach which was to consider the contribution of
a compound to aroma as a function of its threshold of perception.
Examples of the olfactory sensitivities of two experts to ten
key components in wine. On these diagrams, sensitivities labelled
10 correspond to a subject who is highly sensitive to the odorant
substance symbolised by an emitting source, while 0 corresponds to
someone who is little sensitive. Expert A was virtually unable to smell
banana (a fruity odour that is notably characteristic of young wines)
or coconut (characteristic of barrel-aged wines). Expert B was very
little sensitive to cork taint, which is nonetheless a well-known defect
in wines. The grey area contains 80% of the olfactory sensitivities
of the expert population.
EXPERT A
Floral, violet, fruity
10
Mushroom
8
Peppery
6
4
Coriander seed,
floral, citrus
Earthy
2
0
Banana
Stable, leather
Butter
Cork
Coconut
Do experts have special noses?
Expert wine tasters are not always unanimous in their comments and judgements. Based
on this observation, a Université Bordeaux Segalen and INRA team focused on the olfactory
capacities of these experts and demonstrated considerable variations between individuals.
Their study also revealed that tasters with ”perfect“ olfactory sensitivity do not exist!
To improve sensitivity to a particular odour, the researchers therefore proposed specific
training and learning methodologies; these produced positive results following repeated
exposure to an odorant substance and, more unusually, using mental olfactory imaging.
EXPERT B
Floral, violet, fruity
10
Mushroom
8
Peppery
6
4
Coriander seed,
floral, citrus
Earthy
2
0
Banana
Stable, leather
Butter
Cork
Coconut
News Office I +33 1 42 75 91 69 I [email protected]
5
It’s in the bouquet!
Wine is a complex substance that contains nearly 1500 different volatile or non-volatile
compounds, a lot of water, sugars and obviously ethanol. There is also glycerol (the role
of which is still little understood), minerals and polysaccharides (or complex sugars).
As for the category of polyphenols 2, this contains anthocyanins (pigments in red
grapes) and tannins, which play a crucial role in our perception. Last but not least of the
components in wine are the aromas. They may be fruity, floral, suggestive of animals
or spices... they appear and disappear during a wine’s development and have a major
organoleptic impact. For the pleasure of the nose and palate, the bouquet of a wine
evolves, diversifies and becomes more complex over time. So while INRA researchers
analysing how our senses react, they are at the same time trying to determine the
compounds found in wine.
The softness of dry wines
© Inra - Axel Marchal
FOCUS on aromas
Molecular representation of Quercotriterpenosides,
a new family of sweetening compounds released
by oak wood.
Most fine dry wines are devoid of sugar in the chemical sense of the term. But paradoxically they nevertheless develop
a softness - or sweetness - that remains a mystery. Past observations suggested that during the winemaking process,
yeasts and oak wood release compounds with a sugary flavour that are responsible for the sweetness of these wines.
This has now been proved. A team from the Institute of Vine and Wine Sciences in Bordeaux (ISVV) and INRA has, for the
first time, evidenced the involvement of a yeast protein (called Hsp12) in enhancing the sweetness of wine. The scientists
also discovered the influence on this sweet flavour of oak wood during wine ageing. Their studies revealed the existence
of a family of hitherto unknown chemical compounds that are released by oak wood, the quercotriterpenosides, whose
sweetening potential in wine proved to be nearly 1000 times greater than that of sucrose!
Wine aromas
Of the multitude of components present in wine, aromas are amongst those found in the smallest quantities,
although their organoleptic properties are unique. To date, more than 700 aromatic compounds have been
assayed in wines, belonging to three main families of aromas (primary, secondary and tertiary) that are released
during different stages of wine development. In the glass, or even in the mouth, the life of a wine continues.
When they come into contact with air, aromas can evolve; some may dissipate within a few minutes and
others may appear. An important characteristic of dry white wines is the finesse their aromas and fruitiness.
These wines are a balance between two main components: acidity and softness. As for red wines, they are
described as a function of the balance between three components: acidity, richness and astringency.
Understanding astringency
2 Polyphenols are a family of molecules produced by
plants. The great majority of the red and blue pigments
in plants are polyphenols. They intervene in defence
mechanisms against UV rays, fungal attack, etc.
Polyphenols also have beneficial effects on health
and are thus used as additives by the food,
pharmaceutical and cosmetics industries.
6
When you taste an under-ripe redcurrant, tea or a glass of wine, you experience the same sensation, that of astringency.
The interaction between salivary proteins and tannins (molecules produced by plants) participates in reducing
lubrication of the oral mucous membranes, causing the dry mouth sensation that is typical of astringency. These
interactions between tannins and certain salivary proteins - called PRP (or proline-rich proteins, proline being an
amino acid) and whose only known function is to interact with tannins - lie at the heart of research carried out by INRA
teams. Scientists have thus shown how PRP fold themselves around tannins to entrap them, and how the resulting
complexes are at the origin of astringency. More recently, and using an original far-ultraviolet radiation technique,
the scientists were able to localise and very precisely identify the site of interaction between tannins and proteins.
News Office I +33 1 42 75 91 69 I [email protected]
Wines of every hue
From white to red, and passing through very pale pink or cherry red,
the palette of wine colours is immense. White grapes only produce
white wines which have fruity, fresh and light characteristics. As for
black grapes, they can be used to make red, rosé or even - in some
cases - white wines (Pinot noir and Pinot Meunier in Champagne).
It is anthocyanins which give them their red colour.
© Fotolia
How does a wine change its colour?
La vie en rosé
Rosé wines are not made by mixing white and red wines. This practice is only authorised
in some particular cases, such as pink champagne. The principal distinction is between
rosé made by direct pressing (whole or stripped bunches of grapes are pressed directly)
or using the saignée (bleeding) technique (where the grapes are placed in vats in the
same way as when producing a red wine, but only macerated for a very short period of
time). To define and appreciate the quality of a rosé wine, the first criterion for consumers
is colour. A major study conducted by INRA, the Centre du Rosé and the French Wine
Institute enabled the screening of a collection of 298 rosé wines from 21 countries
throughout the world, and it revealed the molecules and mechanisms responsible for
their very broad palette of colours.
Sight is the first sense that is elicited during a tasting. The robe (colour) of a wine
constitutes its external aspect, and several factors can influence this colour. Such
differences, and notably the differentiation between white and red grapes, are above
all linked to genetics: work carried out by INRA has revealed the molecular mechanisms
(regulatory genes) involved in genetic variations in the content of anthocyanins. But
the synthesis of pigments is also dependent on ripeness, climatic conditions and,
first and foremost, on the intensity of solar radiation. A lack of sunshine produces red
grapes that are only lightly coloured, which is why northern regions mainly cultivate
white grape varieties. Two other parameters define whether a red, white or rosé wine
will be obtained: the timing of pressing 3 and the duration of maceration 4. The later
the pressing, the more strongly will the juice be coloured. For white wines, pressing
is generally immediate and there is no maceration, while for red wines, pressing is
performed at the end of maceration. In addition, the colour of a wine can provide
some clues as to its age. Indeed, red wines lose their colour as they age, changing
from a dark purple to a tile-red. As for white wines, they can develop from pale to
golden yellow, or in some cases may take on a brownish coloration.
What about yellow wines?
Ice wines
Gamay Fréaux
Onset of ripening*
At maturity
These wines are produced using grapes that have frozen on the vine. Harvesting
only starts once the temperature has reached at least -7°C.
3 After destemming and crushing, the winemaker collects the free run wine.
The marc (solid components) remain in the vat and are then pressed to obtain the press wine,
which has a stronger colour and contains more tannin (pressurage). The free run wine and press
wine can then be assembled immediately or after ageing, or be aged separately.
4 Maceration: phase during winemaking when the solid parts of the berries - the skins - macerate
in the juice.
© Inra - Zhanwu Dai et Wenling Xia
Produced exclusively in the Jura region of France, vins jaunes (yellow wines) are raised
in a particular way. During their ageing - for between three and six years - the wine
develops its colour and a typical nose reminiscent of walnut, curry or hazelnut. This is
due to the presence of a compound that has been chemically identified and is called
sotolon. In the kitchen, this small molecule can be added (in very small quantities) to
a brioche dough to enhance its flavour.
Teinturier varieties produce grapes with a red flesh. These photos of Gamay
teinturier show the berries on which INRA researchers are working in order
to understand how light regulates the synthesis of anthocyanins.
* Onset of ripening: the moment when the grapes start to take on the colour they will have when
they are ripe.
News Office I +33 1 42 75 91 69 I [email protected]
7
AOC wines,
a family resemblance
“Strongly coloured”, “concentrated“, “lingering in the mouth”, “heavy and rounded”, with
aromas of black and red fruits: that is the style of AOC wines from Anjou-Villages-Brissac
(in the Loire Valley). This family resemblance - or typicality - is a mixture of originality,
authenticity and quality that is linked to the terroir (terrain). It is precisely this link
that binds a wine to its terroir that INRA researchers have been trying to decipher for
many years. Difficult to measure, this link is nevertheless a major challenge for French
viticulture, and is crucial to the production of AOC, or Appellation d’Origine Contrôlée
(controlled designation of origin) wines.
e-terroir
Thanks to the efforts of INRA for more
than 20 years, this on-line app is designed
for winemakers and allows them
to visualise thematic maps of the vineyards
in the Loire Valley: different types of terrain,
soil depth, water reserves, potential
for earliness, etc.
http://www.carto-techniloire.com/
© Inra - Jean Weber
Soil does not make a terroir
Human factors
(viticultural practices)
Terroir
Environmental factors
(soil-climate-associated landscape)
Biological factors
(variety/rootstock)
Harvest (grape quality)
Human factors
(winemaking factors)
Typicality
A survey was performed on 41 producers in the Anjou-Brissac region regarding
their representations of terroir and the factors influencing the styles of their
wines. Questioned about the typicality of their wines, the winemakers were
unanimous: it is the soil that binds this family together. The influence of
vineyard and winemaking practices was minor. But astonishingly, when the
same growers judged this typicality during tasting sessions, the origin of the
plot did not allow them to differentiate the wines from a sensory point of
view. There was therefore a gap between typicality as it was conceived and
perceived by wine producers. In addition, the importance of harvest dates
and the duration of fermentation count a great deal in the style of wines. The
researchers showed that timing of the harvest governed the composition of
a wine from the biochemical point of view. For example, the sugar levels in
grapes have an impact on the typicality of an AOC wine.
Representation of a terroir and its link with typicality
Sensory characteristics
(family resemblance)
Terroir has three dimensions: environmental, biological and human. It endows
the product with notable characteristics (an identifiable family resemblance).
However, these dimensions are complex and the links between them cannot
be measured precisely. Starting from a wine and going back to the soil, the link
involves winemaking practices that may partially mask the role of the soil.
8
News Office I +33 1 42 75 91 69 I [email protected]
Predicting the evolution of appellations
Can producers predict the evolution of appellations and the sensory typicality of wines as a function of
practices? Scientists have developed models by studying the terroir system as a whole. An appellation area
is not defined just by its soils, varieties, landscapes or sensory profiles, but is rather a particular “ecosystem”
that is constantly evolving and associates soils, varieties and practices that will not produce the same wines.
Researchers have therefore preferred to analyse operational sequences, or in other words whole series of
practices, rather than studying a particular practice sequentially.
Appellations
© Inra - Michel Adrian
In France, the National Institute for Origin and Quality (Institut
National de l’Origine et de la Qualité, INAO) is responsible for
appellations, labels and geographical indications. In 2010,
there were 459 appellations and geographical indications
relative to wine (AOC, IGP (protected geographical indication)
and AOVDQS (delimited wine of superior quality, or Appellation
d’Origine Vin Délimitée de Qualité Supérieure), 293 of which
were classified as AOC, and in total 2889 different products
(red, rosé, white, sparkling, etc., or variety names).
AOP, or Protected Designation of Origin (Appellation d’Origine
Protégée) refers to a product whose production, transformation
and processing takes place within a determined geographical
area, using acknowledged and observed know-how. This is the
EU version of the term AOC (Appellation d’Origine Contrôlée)
that is used in France. As for PGI (Protected Geographical
Indication), this is a European identification that was created
in 1992. Initially attributed to specific food products with
a name referring to their geographical origin, the PGI label
was broadened to include wines in 2009.
And why are consumers
attached to AOC wines?
What are the true expectations of consumers in terms of the gustatory quality, price or labelling of wines, or
even the design of their bottles? INRA researchers in experimental economics have provided some answers
to this question by analysing the motivations of purchasers relative to the different characteristics of wines.
Recent findings revealed the importance of AOC labels in the minds of European consumers and assessed
their willingness to pay in different situations. This work placed in perspective the supposed competition
of ”New World“ wines. Furthermore, the team showed that contrary to a common preconception, the
mention of grape varieties in support of an AOC was no guarantee of a greater value being placed on wines.
News Office I +33 1 42 75 91 69 I [email protected]
9
Spotlight on prices
What is the relationship between the price of a wine and its quality? In a connoisseurs
market - for example fine wine auctions - differences in price are quite a good reflection
of differences in the quality of the wines. But in a market that mainly comprises the
uninitiated, what are the factors that can explain differences in wine prices? In fact,
the price of a wine is mainly determined by the ”objective“ characteristics that are
shown on the bottle’s label (ranking, appellation, vintage, for example). Surprisingly,
price is only weakly linked to the quality that might be determined by expert panels
based on sensory criteria.
A few figures
In 2012, approximately 792,000 hectares
of vineyards in France produced 42 million
hectolitres of wine, or about 17% of world
production. 30% of French wines are exported,
which in 2012 represented a value of €7.83
billion. In France, wine ranks third after
the aeronautical and perfumes industries
as a net exporting sector, and is the leading
sector in the agrifood industry.
Source: FranceAgriMer
Les arômes des vins
How wine ”gurus“
influence prices
© Fotolia
Robert Parker is a celebrated American critic known
for his guides on wines and the scores he gives to
wines out of 100. In 2007, INRA economists identified
a ”Parker effect“, taking advantage from the fact that
the ”guru“ had not made his annual visit to France in
2003. The researchers concluded that the scoring of
a wine by Robert Parker led to an average increase in
its price of €3 a bottle, or a 15% increment. For the
most prestigious wines (Pomerol or Pauillac), this
increase could reach €14 a bottle. The Parker effect
is always positive: all wines are more expensive if
they have received the blessing of the master, even
if his opinion is very guarded!
The records of a famous
Bordeaux château under the microscope
How are the price and yield of a great wine influenced by climatic conditions? Data from the archives of a famous
Bordeaux château, covering the period from 1820 to today, enabled the analysis of a considerable amount of detailed
information: climatic factors (minimum and maximum temperatures, daily rainfall), the dates each year when the vines
entered their three phenological stages 5, and annual yields. Published in 2011, this INRA study showed that the effects
of climate on prices and yields have changed over time. Average temperatures (between April and September) have had
a diminishing effect on yields, probably because growers have improved their control of production factors. By contrast, the
impact of mean temperatures on wine prices has increased over time. In more recent years - particularly between 1980 and
2009 - globalisation (and speculation), and growing interest in wine and wine-related activities (experts, magazines),
have driven prices upwards.
5 Periodic phenomena characteristic of the plant cycle and vine growth;
during this work, the dates of flowering, onset of ripening and harvest were studied.
10
News Office I +33 1 42 75 91 69 I [email protected]
Grapes that are good
enough to eat
© Inra - Françoise Dordor et Clotilde Verries
Polyphenols
under the microscope
An Alicante Bouschet grape cut in half prior to the onset of ripening. At this stage, only the pulp in this teinturier variety
is coloured by red pigments, starting from the base; in the upper part, the pulp is still translucent, so it is possible to see
the shadow of the pips and the brush attached to the stalk that distributes sap.
The quality of a grape berry - the starting material for wine production - is
essential to the final quality of the product. The pulp mainly concentrates water
(between 75% and 90%), sugars, acids (tartaric and malic) and minerals.
The skin of the grape contains the aromas and their precursors, as well as the
polyphenols that are so important to the taste, stability and colour of the wine.
Finally, on the surface of the berry, a varied microflora of fungi, yeasts and
bacteria develops and intervenes in development of the wine and its sensory
characteristics. For example, the taste of sweet white wines results from a
filamentous fungus (Botrytis cinerea or noble rot). Starting from this cocktail
found in the grapes, and as soon as they are crushed, reactions are initiated.
They then continue throughout fermentation and ageing. It is essential to fully
understand the ingredients in this cocktail, which is why INRA researchers have
been trying to identify the genes and structure of the compounds founds in
the fruits, and also the mechanisms by which they form.
The secret of Pinot gris lies in its skin
© Inra - Gilles Pelsy
The genome of the grape epidermis differs from that
of the berries themselves: it is a natural chimera! The
grey character of Pinot is due to the combination of
the epidermis of a Pinot noir around a berry that
has become Pinot blanc through naturally-occurring
genetic mutations (also referred to as spontaneous
mutations)! Studies have revealed that the difference
in colour between black and white varieties is due
to the insertion of a mobile element in a gene that
controls the synthesis of anthocyanins.
Mutants of Pinot gris evolving towards Pinot blanc
because of their chimeric structure.
Polyphenols are major constituents in wine. The principal
types are anthocyanins (pigments contained in the skin
of the berries) and tannins found in the skin, pips and
stalk 6. Anthocyanins, which are responsible for red
coloration, are important participants in the quality of
fruits, juices and red wines. But the great majority of
these molecules are methylated (CH3 groups are attached
to them), which intensifies their colour and endows
them with considerable stability. INRA teams, working
in collaboration with Italian researchers, have identified
the gene responsible for this methylation of anthocyanins
in grapes. They have also evidenced other genes which
trigger the transport of anthocyanins, and other reactions
involving polyphenols. In the future, these genes may
serve as markers in genetic selection programmes.
6 The stalk is the green part of the bunch (without the grapes).
Step by step cuisine:
Wöhler sauce with polyphenols!
Thanks to an extraction and fractionation process
developed at INRA, it is now possible to extract
polyphenols from wine in the form of a powder called
“provinol”. In the kitchen, it has been suggested that
this product could be used to make a sauce made
solely from compounds (and not plant or animal
tissues): the “Wöhler sauce”, named after the first
chemist to synthesise an organic compound in 1828.
The recipe: dissolve 100 grammes of glucose and
2 grammes of tartaric acid in 20 centilitres of water;
then add 2 grammes of polyphenols, salt, and a little
piperine (a pepper derivative), a sheet of gelatine and
a spoonful of cornflower. Bring to the boil and then
form an emulsion with oil. Some chefs use this sauce
to accompany shellfish such as lobster.
News Office I +33 1 42 75 91 69 I [email protected]
11
Sugars and maths
FOCUS on aromas
Other key components in grapes are sugars (glucose and fructose). Genotype, environment, and viticultural management...
numerous parameters directly influence the sugar levels in these berries and their metabolism. INRA researchers have
developed a mathematical model that can predict the accumulation of sugars in different types of grapes and under
different growth conditions. This type of model could help winegrowers to choose or adapt their wines and practices
in a given region.
Primary aromas
Citrus, blackcurrant, pepper... are all examples of primary
(or varietal) aromas. Grapes from practically all varieties are
little aromatic themselves, and contain very few so-called
primary (or pre-fermentation) aromas. These aromas, which
give a wine its typicality, result from the metabolism of the
grape during ripening. They are characteristic of a variety or
family of varieties. They are present in the fruit either in an
odorant state - when they participate in the aromatic palette
of the wine without prior transformation - or in an odourless
form called an “aroma precursor” (such as the terpenes in
Gewürztraminer or the volatile thiols in Sauvignon blanc). The
odorant potential of these precursors will then be revealed
during wine production (alcoholic fermentation, ageing).
Molecules that taste of sweet pepper! While studying how grapes manufacture their
aromas, researchers at the Institute for Vine and Wine Sciences in Bordeaux and INRA identified
a gene responsible for the synthesis of methoxypyrazines in these berries. The molecules, which
are particularly important in Sauvignon grapes, give a sweet pepper aroma to our wines! Their
effects are so powerful that a single drop would suffice to flavour an Olympic swimming pool
with sweet pepper!
© Fotolia
The commonality between a rose and a glass of
Gewürztraminer? The floral aromas of this wine are due
to odorant molecules that are also found in the perfumes
of many flowers: terpenes. It is the exceptionally high levels
of terpenes found in Muscat and Gewürztraminer wines
that give them their characteristic aromas. Studies at INRA
have enabled identification of the genetic origin of muscat
aromas, linked to a point mutation located in a gene called
DXS. This discovery offers promising perspectives in biotechnology, notably for the production
of terpenes of pharmacological interest.
INRA’s seedless grapes
Three white varieties (Danuta, Exalta and Madina)
and one black (Alvina) were created through
crossing and selection. Obtained in 1964 by
crossing Dattier de Beyrouth and Sultana moscata,
Danuta was the first seedless variety to be
registered in the official French catalogue in 1990.
The vine genome deciphered...
In 2007, an international collaboration, which notably involved scientists from the Genoscope and INRA, obtained a high-quality sequence
of Vitis vinifera. Publication of the vine genome sequence was the starting point for a detailed characterisation of the functions of the genes
in this plant. More recently, in early 2012, INRA opened a phenotyping platform in Colmar that is unique in Europe. This facility that enables
the observation of vine behaviour is designed to encourage the creation of new varieties that will be sustainably resistant to the principal vine
diseases (downy mildew and and powdery mildew). These varieties will have to meet demands concerning limitations on pesticide use,
while at the same time guaranteeing high-quality and competitive wine production.
12
News Office I +33 1 42 75 91 69 I [email protected]
Innovations from
harvest to the bottle
For the past twenty years, experimental studies initiated by INRA have produced
technological tools which have been transferred to professionals in the sector. A
dynamic crusher, Flash détente, decanter centrifuge, cold maceration, etc., are all new
practices that offer winemakers enhanced accuracy and operational control. A look
back at these technological innovations as they affect the process of transformation
of grapes into wine.
A new concept:
”precision oenology“
© Fotolia
Destemming, pressing, fermentation, extraction,
stabilisation, packaging... the concept of precision
oenology can be applied to all stages in the production
of a wine. It involves not only new working practices
but also the mastery of oxidation phenomena,
and the control of all factors that determine wine
quality (for example, aroma precursors, polyphenols,
compounds that are produced during winemaking
or ageing). Finally, this concept also integrates ecodesign and sustainability approaches.
Dynamic grape crushing
© Inra - Christophe Maître
The first step in the journey towards a wine is often destemming (or stripping)
that separates the berries from the stem, as the latter may give green aromas
to the wine that are little appreciated. Innovations have improved both
this destemming step and mechanical sorting, both in the vineyard during
mechanical grape harvesting and in the winery. After the grapes enter the
winery, they fall into a crusher where the berries are crushed to release the
juice (or must). A new process to split open the berries, developed by INRA
researchers in partnership with the company Pellenc, has been developed:
the dynamic crusher. This enable a more rapid and efficient extraction of the
juice because the berries are fully opened. In 2013, this technology moved to
an industrial production stage. For white wines, the next step in the process
is pressing, followed by an essential settling step, which consists in clarifying
the must by removing all particles in suspension.
News Office I +33 1 42 75 91 69 I [email protected]
13
A hot flash on the harvest!
Throughout the world, winemakers frequently apply liquid phase production technologies that involve heating their
harvest (thermovinification). In the early 1990s, INRA researchers focused on this area and developed an unique technique:
Flash détente. First of all, the grapes are heated rapidly (in an oxygen-free atmosphere) so that within a few minutes,
a maximum temperature of 90°C is reached in the centre of the berries. The heated grapes are then transferred to a vat
under a vacuum, where an abrupt drop in pressure causes immediate cooling and the release of steam: the ”détente“
(relaxation). This technology causes mechanical destructuring of the cells in the grapes which favours the release of the
compounds targeted. Flash détente thus enables optimisation of the next step in winemaking, and produces wines with
greater typicality. This physical pre-treatment of the grapes is the starting point for numerous winemaking methods, and
also the production of grape juice that is both more richly coloured and contains more polyphenols.
Carbonic maceration
”Micro-winemaking“ vat, settling tank.
© Fotolia
As early as 1874, Pasteur expressed his intuition
relative to this phenomenon, but it was only
in 1934 that a scientist in the Wine Research Unit
in Narbonne (which would later become an INRA
unit) developed this process. Carbonic maceration
consists in placing whole clusters of unbroken
grapes - harvested by hand - in an atmosphere
that is depleted of oxygen and saturated
with carbon dioxide, in order to exploit the
spontaneous fermentation that occurs under such
conditions. The transformation then occurs inside
the berries, and is due to endogenous metabolism
of the fruit, thanks to the action of enzymes
specific to grapes and without the intervention of micro-organisms. The grapes are
then subjected to ”standard“, microbial fermentation for 8 to 10 days. This process enables
smoother implementation of the different phases of winemaking that follow, and gives
the wine a greater overall harmony.
Continuous juice production
The emblematic stage of pressing, which may be mechanical or pneumatic (or
in other words, intermittent, often for white and rosé wines), can be replaced
by an alternative, continuous process if a decanter centrifuge is used. This
new tool - studied by INRA - enables the extraction of juice with a yield that
is comparable to that of a wine press, and with a degree of clarification that
is generally adapted to the winemaking process, notably in the case of white
and rosé musts.
When the wine macerates...
© Inra - Christophe Maître
14
News Office I +33 1 42 75 91 69 I [email protected]
Maceration in fermentation vats consists in extracting constituents from the solid
parts of the harvest (tannins, anthocyanins, colorants, aroma precursors). This
is a crucial stage in the production of a red wine, and there may be differences
between wines; for example, those for laying down require a longer maceration.
Cold, pre-fermentation maceration (4 - 15°C for a few days) is a variant of
traditional maceration: using ripe grapes, it can obtain red wines expressing
more intense, fruity notes. For white and rosé wines, maceration consists in the
contact for just a few hours between the grape skins and the juice, thus allowing
aromatic precursors and anthocyanins (for rosé wines) to leach into the latter.
Automated fermentation
This process allows the yeasts to gradually transform sugar into alcohol. It is carried out in a vat (generally made of stainless
steel) and lasts from a few days (for a dry wine) to several months (for a sweet wine). Fermentation generates large
quantities of carbon dioxide and a rise in temperature that may be harmful to both the yeasts and product quality. INRA
teams have proposed new control strategies for fermentation based on the on-line monitoring of its kinetics (measuring
the rate of carbon dioxide emissions) and vat-by-vat optimisation of the temperature profile and nutrient supplementations
(mainly assimilable nitrogen and oxygen). These strategies are already enabling more reliable fermentations. The next
phase in this work will consist in using automation to drive the aromatic profile of wines.
Winemaking vats.
Wine remains unstable for as long as it is not protected by the addition
of sulphites, and if malolactic fermentation has not yet occurred.
This malolactic fermentation is able to reduce the acidity of wines
by facilitating the transformation of malic acid into lactic acid by lactic
acid bacteria, at a temperature of around 20°C. Of particular value in red
wines, this fermentation is not desirable for white wines. The wines
then continue to follow their path: racking consists in running the wine
out of the vat by separating it from the cap of marc 7 and the lees
(deposit of dead yeasts). This stage enables elimination of the carbon
dioxide acquired during the alcoholic and malolactic fermentation
processes.
© Inra - Yves Cadot
The end of the road
During fermentation, racking and returning (delestage) consists in recovering all the must that has accumulated
in the bottom of the vat and transferring it to a second vat. It is then poured over the marc cap that has become
compacted in the bottom of the maceration vat. As for piégeage, this is an operation specific to red wine
production during which the marc cap is punched downwards and crushed into the fermenting juice in order
to encourage the dissemination of phenolic compounds and aromas.
The chemistry of sulphites
SO2, or sulphur dioxide, is used during winemaking
for its antiseptic and antioxidant properties. It prevents
”bad“ micro-organisms from turning the wine
into vinegar, while at the same time allowing other
micro-organisms to do their work, or in other words,
turn grapes into wine. The sulphiting of wine can
protect it from oxidation. In France, it is compulsory
to indicate on a wine label whether sulphites have
been used during its production. Current research
is trying to develop wines that contain less or even
no sulphites but which retain their organoleptic
characteristics.
The wine continues its voyage with the assembly of components from the different vats available. Once
assembled, the wine is aged in vats (under micro-oxygenation) or in barrels. ”Primeur“ wines (in the sense of
”new“, such as Beaujolais nouveau) are not aged. Topping up consists in ensuring the periodic filling of barrels
to compensate for losses from evaporation. Fining involves the addition of a protein-based substance. Egg white
was used in the past, but numerous other techniques and compounds are now available to clarify and stabilise
wines by causing the precipitation of particles in suspension. Finally, the wine may be filtered before bottling.
The largest collection
of vine varieties in the world is held by INRA!
7 The marc cap designates the solid parts of the grapes
© Inra - Florence Carreras
On the shores of the Mediterranean, between Sète and MarseillanPlage (Hérault), INRA owns and manages the largest conservatory
of vines in the world. The Domaine de Vassal experimental farm
groups more than 7500 accessions (elemental samples in a
collection of varieties) grown on 19 hectares that are wholly
dedicated to the conservation, characterisation and exploitation
of vine biodiversity. In Bordeaux, Colmar and Angers, INRA also
holds other collections of varieties, accessions and rootstocks 8.
(stems, pips, skins) that are macerated during fermentation
and rise to the surface under the action of carbon dioxide release.
8 Main underground part of a vine that is resistant to phylloxera
(a vine pest), onto which the scion of a fruit-producing variety
is grafted.
News Office I +33 1 42 75 91 69 I [email protected]
15
These yeasts
that can make good wine
Grapes turn into wine under the action of fermentation yeasts, micro-organisms whose
role no longer needs to be proved. They are to wine what breadmaking yeasts are to
bread. Thanks to them, almost all the sugars present in grapes are transformed into
alcohol. The diversity of yeast species and strains contributes to the sensory complexity
of wines. But how do they react to disturbances? How can these strains be improved?
These micro-organisms are the subject of particular attention from researchers.
Yeasts and genes
In 2009, INRA teams working in collaboration with the National
Sequencing Centre, were able to sequence the genome of a wine
yeast: Saccharomyces cerevisiae. The scientists showed how its
genome has evolved in a spectacular manner by retrieving genes
from other yeasts in wine. This was the first time that the acquisition of eukaryote genes 9 belonging to species distant from
yeasts had been demonstrated in Saccharomyces cerevisiae. The acquisition, maintenance and amplification of
these foreign genes suggest that they may contribute
to adapting these strains to their particular ecosystem,
and understanding these molecular mechanisms facilitates the choice of yeasts for winemaking. This has led
to efforts to improve Saccharomyces cerevisiae strains, for
example by endowing them with a nutritional advantage
at the end of fermentation. These studies also enabled the
development of a strain overproducing esters (compounds
which participate in the bouquet of a wine, giving it a fruity
note), and reducing the production of acetate (a compound that
is undesirable at high levels). Trials confirmed this strain’s potential to produce aromatic, fruity wines, and it was put on the market in 2012. A strain producing low levels of sulphur dioxide was also
selected, while another - producing little alcohol - is currently under development. Finally, global mathematical modelling studies are ongoing to analyse
the respective roles of the metabolism of carbon and nitrogen and aromas, which will
help to understand and predict the behaviour of yeast during fermentation and at the production of aromas which play a key role in the organoleptic balance of wines.
9 Living organisms with a nucleus containing DNA that is isolated from the cytoplasm by a membrane.
Yeasts are single-cell eukaryotes. On the other hand, bacteria are prokaryotes (their DNA is not bundled up in a nucleus).
16
News Office I +33 1 42 75 91 69 I [email protected]
Budding of Sacchromyces cerevisiae
(scanning electron microscopy).
© Inra - Jean-Michel Salmon
Winemaking wasps!
Secondary aromas and aroma precursors
By far the most abundant, secondary (or fermentation) aromas contribute fruity,
floral or vegetable components. These aromas are linked to the activity of yeasts
and bacteria during alcoholic and malolactic fermentation processes. Some of
these aromas are common to all types of wine, while others result from the release
of varietal aroma precursors and are more typical. While aromas suggestive of
brioche, bread and beer are attributed to yeasts, milky and buttery aromas are
a result of bacterial fermentation.
Driving aroma production during fermentation? Fermentation aromas
play an important role in the aromatic profile of young wines. Several studies,
performed using original approaches (post-genomics, on-line monitoring, etc.)
have enabled major advances in our understanding of their synthesis by yeasts,
and particularly that of esters and higher alcohols linked to nitrogen metabolism.
A study currently under way at INRA will try to propose management methods
for fermentation that can drive the aromatic profile of wines.
© Fotolia
FOCUS on aromas
The essential role of these insects was revealed for the first time in 2012 by INRA researchers, who showed how wasps are
reservoirs and vectors for the yeasts present in grapes from year to year. Their results demonstrated the close relationship
between these microflora and the fauna associated with a vineyard, and suggested that any environmental change
affecting insect biodiversity might create a major risk of diminishing the biodiversity of yeasts and hence have an impact
on the quality of fermented products.
Aromas as new, natural food ingredients! Working with their industrial partners, INRA researchers have developed a
technique to capture the aromas that are released from fermentation vats. These trapped aromas are extracted and can be added
to drinks such as alcohol-free wines or sodas, contributing a fruity flavour, a fermented character and freshness; in other words,
a new and natural ingredient for the food industry.
Aroma precursors: the case of volatile thiols. Some aromas exist initially in the form of precursors that are odourless in
grapes. Under the action of yeasts or bacteria, molecular transformations occur and these precursors then release their aromas.
This is the case of volatile thiols. They are highly characteristic of Sauvignon blanc wines, whose principal descriptors are broom,
blackcurrant buds, grapefruit, passion fruit, citrus notes and in some cases smokiness or roasted meat. INRA researchers have
developed methods that can determine different classes of volatile compounds and their precursors. For example, they have
identified the aromas specific to Syrah and Grenache varieties, and varietal thiols in Sauvignon blanc.
The aromas of Riesling. Riesling and Sauvignon blanc are two historic varieties whose wines are much appreciated for their
remarkable aromatic characteristics. In collaboration with colleagues in Germany, a team from Université Bordeaux Segalen,
involving INRA, has studied the aromas of Riesling wines by comparison with those of Sauvignon blanc. Citrus and yellow
fruits are the descriptors associated with Riesling. Furthermore, this wine contains high levels of 3-sulfanylhexanol, a highly
odorant volatile thiol reminiscent of the odours of grapefruit and rhubarb. In addition, studies have led to the unexpected
identification of ethyl trans-cinnamate, a highly odorant compound with fruity and floral notes, which is present in Riesling
wines at concentrations that are sufficiently high to contribute to their aroma.
News Office I +33 1 42 75 91 69 I [email protected]
17
New winemaking practices
At the end of fermentation, the wine is cloudy, gassy and unstable. It is then run off
into stainless steel vats or oak barrels reserved for ageing, during which it becomes
refined and clarified. INRA researchers have developed a certain number of innovations
and processes that can help winemakers to improve the quality of their wines. The
objectives are optimum microbiological stability, ideal clarity and rapid and efficient
bottling. Studies are ongoing at all levels of winemaking, and include processing the
waste it generates, with notably the development by INRA of a biological pollution
control process that uses activated sludge.
The Pech Rouge Experimental Unit
© Inra - Christophe Maître
With its experimental facilities and different
installations (winemaking unit, microbiology,
delayed fermentation, extraction and separation
techniques, ageing, etc.) - covering a total
of nearly 5000 m2 - the INRA Pech Rouge
Experimental Unit (Montpellier Research Centre)
based in Gruissan near Narbonne is the focus for
the transfer by INRA for all findings that affect
winemaking and the vine-grape-wine continuum.
Its mission: to innovate in collaboration with
the Sciences for Oenology Joint Research Unit
(Montpellier) and coordinate the dissemination
of information to development agents. To achieve
this work, the Experimental Unit runs a
170-hectare estate (40 hectares of which is
planted with vines) that also contains analytical
laboratories, technological tools and finally a
Sensory Analysis Laboratory which enables the
tasting of different wines.
www.montpellier.inra.fr/pechrouge
Capsuling and labelling.
Through the membrane
For the past 20 years, researchers have constantly been imagining new membrane-based processes. These include
electromembrane systems that can extract ions from wine to ensure its sustainable stability once it has been bottled.
Other processes, using dense or porous membranes, enable a reduction in the alcohol content of wines. These membranes
of different types and with selective permeability, can all improve wine quality.
18
News Office I +33 1 42 75 91 69 I [email protected]
◗ Eliminating tartrate deposits
In bottles of wine, tartaric acid, potassium and calcium may combine naturally to form tartrate salts whose presence
is not appreciated by consumers. INRA researchers have developed a technique that can prevent these deposits by
eliminating excess potassium and tartaric acid from wine before it is bottled: tartrate stabilisation by membrane
electrodialysis. This involves the simultaneous extraction of anions (negative ions) and cations (positive ions),
resulting from the alternation of anionic and cationic membranes. This technique has been authorised since January
2002, including for PDO wines. This highly qualitative process is now being developed in all winemaking countries
throughout the world because of its reliability. This membrane technology also means it is no longer necessary to add
various stabilising compounds to the wine.
Calcium tartrate. Deposit in wine.
◗ Acidifying/de-acidifying wine
© Inra - J.P. Meyer
For numerous reasons (climate change, viticultural practices, etc.), the pH of wines has
tended to rise in recent years; in other words, wine has become less acid. But acidity has
a crucial effect on both bacteria and the organoleptic properties of a wine. To lower the
pH of wine, INRA researchers have developed a electromembrane process to acidify wine
that is both controlled and reliable. Approved since January 2011, this treatment is now
available at an industrial scale, including via service providers operating mobile units. By
contrast, in order to raise the pH, it is possible to de-acidify wine using electromembrane
processes that have been authorised for winemaking since February 2013 and involve
the extraction of excess organic acids. This new research area is of particular interest
to Northern winegrowing countries.
◗ Optimum filtration!
For commercial purposes, it is necessary to achieve the highest possible clarity and microbiological
stability of a wine, and this is the objective of tangential microfiltration. Having been the subject
of basic research by INRA, clarification by tangential filtration allows the liquid to circulate
along a special membrane at a relatively high rate (a few metres per second) and then pass
it through the membrane under the action of pressure. These processes are now being
used increasingly by producers.
At present, the most sophisticated installations combine these different technologies:
the on-line treatment of raw wine to enable rapid bottling that also ensures the clarity
and microbiological and tartrate stability of wines. A major advance for producer-based
bottling plants, these continuous, on-line and automated treatments can guarantee the
quality and traceability of wines. Traditionally, winemaking practices involved the use
of technological auxiliaries, inputs that were subsequently eliminated from the wine (e.g.
fining). At present, INRA is devoting many of its research projects to the development of wines
that contain the fewest possible additives, thus avoiding recourse to stabilisers or ion exchange resins.
Surface crust that has formed during the tangential
microfiltration of a red wine.
© Inra - Didier Cot et Aude Vernhet
Pulsed electric fields
This technology under study at INRA enables satisfactory microbiological stabilisation by varying electrical intensities
and treatment times. This work has shown that the process is efficient in increasing the extractability of phenolic
compounds from the skin (tannins and anthocyanins). The quality of the vines produced using this low-energy technique
complies with that obtained using traditional winemaking methods.
News Office I +33 1 42 75 91 69 I [email protected]
19
Clouds in white wines
What happens at ambient temperature in a white wine? During the transport or storage of these wines, a “protein
breakdown” (visual disturbance) may occur and constitutes a defect in the eyes of consumers. This breakdown is attributed
to slow modifications to the conformation of proteins, leading to clumping phenomena. Although the mechanisms
underlying this instability are well known at high temperatures, INRA researchers have now studied this phenomenon
at ambient temperatures. They have demonstrated the combined impact of pH, ionic force and temperature on the
onset of these protein disturbances. Two paths can be followed in order to limit this phenomenon. Firstly, it is possible to
apply a fining treatment to the must; research has shown that this can lower the level of bentonite 10, stabilise the wines
without slowing down alcoholic fermentation (in fact, on the contrary), and above all reduce the undesirable effects of
fining on the quality of the finished wine. Another method is currently under development: specific elimination of the
proteins that are responsible for this breakdown. This work opens new
perspectives regarding methods which could replace current stability
tests and treatments.
10 Used for the fining of white wines, bentonite is a natural clay with
a negative electrostatic charge that enables the adsorption of proteins
with a positive electric charge.
The control of dissolved gases
FOCUS on aromas
© Inra - J.P. Meyer
Thermal emission from the bottom of a barrel, visualised using an infrared camera.
Tertiary aromas
Vanilla, coconut, spicy or toasty aromas after ageing in oak barrels; chocolate, prune or
walnut aromas with some naturally sweet wines; leather, animal or earthy aromas in
some bottled wines. These tertiary aromas develop while wines are aged in vats, barrels
or bottles. Generation of these aromas is closely linked to the oxidation-reduction
reactions that occur in wine. For this reason, the presence of higher or lower levels of
oxygen, and how it penetrates into the wine, play a crucial role.
© Inra - Christophe Maître
20
News Office I +33 1 42 75 91 69 I [email protected]
Since winemaking first started, it has been known that oxygen plays
a very important role in stabilising the colour of red wine and and the
development of its aromatic notes. Too much oxygen, and oxidation
phenomena appear. Insufficient oxygen, and reduction phenomena
will develop, which may even product sulphur-based compounds
with an odour reminiscent of rotten eggs... After cork taint, these
oxidation and reduction defects are the principal changes that can
affect wine quality; hence the importance of controlling oxygen levels
throughout wine production. Today, recent technological advances have
made it possible to measure oxygen levels at the different stages of
winemaking. At an experimental level, research has produced a tool
that can control dissolved gas levels using a membrane technology
(by raising or lowering carbon dioxide or oxygen levels). Another
INRA advance in the analytical control of dissolved gases consists in
measuring oxygen levels by luminescence and carbon dioxide levels
by laser spectroscopy, without affecting wine samples.
In addition, INRA is currently developing a cutting-edge innovation: the
packaging of wines containing controlled dissolved gas levels, called
Condinnov. This project involves studying wine in bottles or a bag-inbox 11 system at an experimental scale of 20 to 100 litres on the one
hand, and at an industrial scale of 10 to 100 hectolitres on the other.
With Condinnov, oxygen and carbon dioxide levels are adjusted by
bubbling gas through the preparation vat (or in other words, through
the liquid) and/or using a membrane contactor system. A ”line“ has
enabled the homogeneous bottling of experimental batches.
11 Bag-in-Box ou BIB®: a widely-studied packaging system that takes the form
of a bag filled with wine under a vacuum.
© Fotolia
Corked wine?
A new range of synthetic corks
As both a lung and a filter, the cork allows the circulation of gases between the wine and the external environment.
Depending on whether this exchange is equilibrated or not, the wine will age well or poorly. A short and porous cork
facilitates these exchanges and activates ageing. For great wines that are meant to be kept for many years under optimum
conditions, very long, top quality corks are used. Another essential quality of a cork is its flexibility. After being compressed
during corking, it must be able to ”re-expand“ in order to seal the bottle’s neck in an airtight manner. In this area, INRA
researchers and their industrial partner Nomacorc have studied the influence of the oxygen transfer rate on the sensory
attributes of wines made using Grenache grapes during ageing. A series of four synthetic, more or less hermetic corks was
tested for 10 months on wines packaged in 375 millilitre bottles (the equivalent of about 20 months of ageing for a standard
bottle of 750 millilitres). Their findings demonstrated the potential offered by the appropriate management of oxygen to
encourage the expression of certain sensory attributes. Based on these results, Nomacorc has pursued the development
of a new range of synthetic corks that are classified according to different oxygen transfer rates.
Most blame for this combined odour
of mould and wet cardboard can be laid
on cork. This natural product, made from
the bark of the cork oak, is endowed with all
the essential qualities necessary to close a
bottle: airtightness, flexibility and porosity.
However, natural cork may also be partly
responsible for cork taint, because of the
presence of a compound that can develop in
the bark of the cork oak: trichloroanisol (TCA).
Studies have revealed other possible reasons
for cork taint: wooden barrels, conditions
during shipment, etc.
An innovative and ecological packaging system
INRA is a partner in the Novinpak® project that was set up in 2009. It aims to develop lightweight packaging systems for
high-quality wines, based on recycled PET plastic. This new packaging must comply with regulatory requirements and
be adapted to the demands of both consumers and distributors.
AND HEALTH
Is drinking wine good for your health? This is a thorny problem.
In France, wine accounts for two-thirds of all the alcohol consumed
by individuals. Twenty years ago, the concept of the French paradox
was born of the observation that despite identical risk factors, French people benefited from better cardiovascular health than their neighbours
in northern Europe or among Americans. International studies focused on certain components in wine (such as particular polyphenols) and
suggested their protective effects on our cardiovascular system. But it is not that simple, because the cardiovascular health of an individual results
from both genetic and behavioural factors, such as diet, physical activity, alcohol consumption or smoking, etc.
In the context of this complex relationship between wine and health, cancer has been the subject of numerous studies which have shown that
the risk of onset of a cancer (upper airways, colon, breast or liver) increases statistically significantly as from an average consumption of 10 grammes
of alcohol (or one standard glass) per day. The risk increases in line with the amount of alcohol consumed. INRA and INSERM researchers studied
the consumption of alcoholic beverages, including wine, by 29,566 adults belonging to the NutriNet-Sante cohort. They demonstrated that the
share of wine in alcohol intake increased in line with age and income, and observed that people consuming more than 10 grammes of alcohol
per day cumulated more risk factors for cancer (e.g. age, smoking, excess weight, sedentary lifestyle, poor diet, etc.) than those consuming less
alcohol. This observation demonstrates the importance of increasing efforts with respect to prevention.
News Office I +33 1 42 75 91 69 I [email protected]
21
Climate change:
which wines for tomorrow?
What are the effects of climate change on vines and wines? How can winegrowers
adapt to this change? Which scenarios can be applied to French winegrowing regions
in 2050? In March 2012, INRA initiated a multidisciplinary project federating 23
research units around these high priority issues. Named Laccave (Long term impacts
and Adaptations to Climate Change in Viticulture and Enology), this programme aims
to examine the principal effects of climate change on vines and wines and to explore
different innovations and strategies for adaptation.
3 weeks ahead
in 30 years
© Fotolia
Data collected by INRA over the past thirty years
have proved that combined with changes to certain
cultivation methods, global warming has already
pushed forwards the entire growing cycle of vines,
from flowering to harvest. Today, grapes are harvested
between two and three weeks earlier than they were
thirty years ago! The berries are sweeter and less
acid, which produces wines containing more alcohol
and less acidity. In the longer term, climate change
may also have an impact on yields, the varieties
grown, diseases and pests. In southern France, the
principal consequences may be a reduction in yields
and wines that are more concentrated, including in
alcohol. In northern areas, grapes will ripen better,
causing modifications to the aromatic profiles of
wines. New regions may also start producing wine,
such as Brittany or south-eastern counties in the UK.
Vines and vineyards in the future
In each winegrowing region, actors are mobilising their efforts and envisaging levers for possible adaptations, which
include selecting later varieties or those producing less sweet grapes, using yeasts that limit the transformation of sugar,
managing future planting schemes based on simulations of climate change, modifying the regulations, etc. Numerous
ideas are under study in the context of the Laccave project; here are a few examples:
◗ Analysis of economic strategies
What are the economic conditions for the adaptation of producers and consumers to global warming? At INRA and the
Institute of Vine and Wine Sciences in Bordeaux, economists and oenologists are analysing the heterogeneity of consumer
tastes and willingness to pay for wines produced under specific conditions of late harvesting and the overmaturation of
grapes. In 2013, they initiated a study that notably involves some thirty tasting experts and a hundred regular consumers. Its
results will supplement other work being carried out at INRA on how consumers perceive a lower alcohol content in wines.
22
News Office I +33 1 42 75 91 69 I [email protected]
© Fotolia
◗ Facilities that are unique in the world
In the context of potential changes to the varieties grown in the Bordeaux region, an experimental plot grouping some
fifty varieties has been set up on INRA’s experimental farm, with the support of professionals from the Bordeaux vine and
wine industry. Planted in June 2009, this plot - named Vitadapt - is unique in the world: 52 varieties, all grafted on the
same rootstock, were selected and will be monitored each year for at least thirty years. Numerous measurements are
being performed and include vine phenology and grape ripening parameters. This plot is now coming into production
(first harvest in 2011) and micro-vinifications are planned in the years to come in order to characterise the winemaking
qualities of the varieties planted. This work will supplement other INRA research on the vine developmental cycle and
varieties producing grapes with a lower sugar content.
◗ Loire Valley: studying the climate at a mini-scale
One of the major French wine-producing regions, the Loire Valley, experiences quite marked climatic nuances that
partly explain the diversity of the wines produced. By experimenting on pilot sites (Coteaux du Layon and Saumur
Champigny), INRA researchers have shown that this diversity also exists at the scale of wine-growing terroirs or
appellations. Furthermore, they have analysed the evolution of the composition of grapes from the six varieties most
widely grown in the Loire Valley. Their results have revealed a widespread rise in temperature and in the bioclimatic
indices 12 affecting vines during the past 60 years. Thus the perspective of climate change may involve a major variability
in grape quality and changes to the typicality of wines. However, this work has also indicated margins for adaptation in
the short or medium term that will ensure maintenance of the quality and typicality of the wines produced at present.
Measuring the heterogeneity
of berries at harvest on a grille
(for random sampling).
© Inra - Yves Cadot
12 These bioclimatic indexes calculate the climatic factors which influence grape quality; they take into account for example the daily
average temperatures above 10°C, cool night temperatures, sugar content, soil properties, etc.
◗ The spectre of drought:
agronomy and precision irrigation
By acting on the opportunities for, and intensity of, irrigation, it is
possible to produce wines with markedly different qualities. INRA
researchers are developing tools to evaluate the water requirements
of different varieties and to manage precision irrigation. The
challenge is to ensure the efficient use of water, with particular
emphasis on preserving this resource. To achieve this, studies are also
ongoing on the use of alternative water sources, such as the collection
of winter rainfall or the use of water from water treatment plants.
News Office I +33 1 42 75 91 69 I [email protected]
© Inra - UEPR
Zoning within a plot of a Syrah plot situated in the Massif de la Clape as a function of changes to the water status of vines between flowering
and ripeness. 1, 2, 3 and 4: zones with rising levels of water stress. 0: irrigated zone. INRA Experimental Farm in Pech Rouge.
23
It’s trendy!
Less sugar and less alcohol
◗ A new range of grape juices
A particular image has always been attached to grape juice: that of a product that is too sweet and is mainly intended
for children! Fijus-R@isol was set up by Foulon-Sopagly, the leading European producer of grape juice, in order to change
this image. Their plan was to create a range of juices with improved nutritional value, containing less sugar, higher levels
of polyphenols and controlled acidity. INRA is involved in the project regarding the choice of new varieties and
the optimisation of cultivation practices. The aim of this programme - which started in 2008 - is to develop
a ”grape juice“ sector that at present only accounts for 4% of the French fruit juice market in volume terms.
This is a real opportunity for growers in this sector, who produce a million hectolitres of grape juice each year.
◗ Alcohol-free wine
Annual wine consumption in France has fallen by half in 40 years, while its alcohol content has constantly
risen (to 12, 14 or even 16%), in contradiction with policies on public health and road safety and also
with changes in dietary behaviour. INRA researchers have been developing high-quality, reduced-alcohol
wines (VDQA), with levels between 6% and 12%. At completion of the VDQA project, four varieties
were selected and different technologies to reduce the final alcohol content were studied (reducing the
sugar content of the must, de-alcoholising the must during fermentation or in the finished wine). The
VDQA project also addressed socio-economic and sensory perception issues. From an aromatic point
of view, these wines are less ”powerful“, but this sometimes allows the development of fruity notes in
the finish. Another observation: consumers tend no longer to consider the product as a wine when its
alcohol content is lower than 9% per volume. Blind tastings concluded that French consumers could
not differentiate VDQA wines from standard wines, when up to 3% of alcohol was removed. Population
surveys, on the other hand, revealed the existence of a market for VDQA wines, notably among women
and the elderly, with men remaining more reticent..
© Inra
Low-calorie, refreshing... an option that is
seeing growing success! An alcohol-free
and low-calorie wine, produced from red
or white wine, has been marketed since
1989 under an INRA licence by the Union
des Caves Coopératives de l’Ouest Audois
et du Razes (UCCOAR). After removing
alcohol by a distillation process under
vacuum and at a low temperature, the
wine-based, alcohol-free drink is notably
enriched with concentrated grape must.
Marketed under the brand name of Bonne
Nouvelle (Good News), more than a million
bottles are currently being sold each year.
◗ Wine with a lower alcohol content
Di@gnoplant
The INRA application Di@gnoplantR-Vigne is a diagnostic tool
that can visually identify some fifty diseases and pests that
affect plants in the vineyard. Images enable users to zoom in
on the cause of the problem they have encountered, whether
it concerns a parasite or not. And for the initiated, a list by
name provides direct access to datasheets that summarise the
knowledge available on diseases and pests.
© Inra - Pascale Inzerillo
24
Service de presse I 01 42 75 91 86 I [email protected]
© Fotolia
And what about organic wine?
The concept of sustainable viticulture refers to a practice that is viable
from both the economic, environmental and human points of view. This
may involve using varieties that are disease-resistant, controlling vine
development, planting hedges around vineyards, etc. Several approaches
to vineyard management can be seen, ranging from sustainable viticulture
to production systems that are even more environmentally friendly. INRA
is supporting the transition towards viticulture that is less dependent
on pesticides. On its experimental plots in Languedoc-Roussillon, in
particular, a multidisciplinary project called Aidy is being carried out,
designed to analyse management practices using an integrated approach
from the plot to the vineyard. The researchers are examining the effects
of switching to organic management (yield dynamics, vigour, weeds,
soil fertility and pest pressures - both diseases and insects). They are also
studying the short and medium term performance of the vineyard, and
the socioeconomic implications of this change. At a European scale, INRA is coordinating a major project called Innovine.
Initiated in February 2013, it aims to develop farming practices that are able to maximise harvest quality in a fluctuating
environment (epidemics, resistance to climate change, etc.). Another objective is to exploit the knowledge generated by
European and international genomics studies in order to improve and diversify vine varieties that are adapted to these
new viticultural practices. Finally, the scientists also intend to develop decision-support tools for winegrowers.
Although organic wines comply with a specification designed to strictly limit the use of certain additives (notably sulphur
dioxide or copper sulphate) and ban others (particularly synthetic compounds), can they be the subject of new winemaking
practices? The answer is ”yes“ in the USA, where electromembrane processes are physical winemaking techniques that do
not require the use of inputs. In Europe, use of the Flash détente system and electromembrane processes is not acceptable,
but these options are likely to be re-examined between now and 2015.
New resistant varieties
New varieties that are resistant to two vine diseases have been created by INRA and are currently being evaluated in the
context of a network involving INRA centres in Colmar, Angers, Bordeaux and Montpellier. The success of these varieties,
resistant to downy mildew and powdery mildew (two diseases caused by pathogenic fungi), will depend on the sustainability of this resistance, the quality of the wines produced and their potential to adapt to climate change. Current studies are aiming to control these parameters in order to develop the best adapted varieties and management practices.
The first varieties - two white grape and two black grape varieties - will be submitted for registration in the official catalogue as early as 2016.
Château Couhins, a cru classé (officially classified)
Graves wine for sustainable viticulture
News Office I +33 1 42 75 91 69 I [email protected]
© Inra
Situated in the outskirts of Bordeaux, the Couhins estate belongs to INRA and benefits from the most
advanced research in terms of sustainable viticulture. The principal research areas addressed are precision
viticulture, integrated production and efforts to reduce inputs. A global approach designed to preserve
soil life and restrict treatments is being applied in this 25-hectare vineyard. Couhins was where the sexual
confusion method was developed, designed to control grape moth, a parasite that perforates grape skins.
In 2010, Château Couhins joined a pilot group of Bordeaux vineyards responsible for demonstrating the value
and feasibility of the Environmental Management System (EMS), a management tool designed to reduce
the environmental impact of companies. And in June 2013, a new, High Environmental Quality building,
and facilities to welcome professionals and lovers of this fine wine, were both opened on the estate.
www.chateau-couhins.fr
25
SCIENTIFIC CONTACTS
4/5
Tasting as the centre of attention
From chemistry to subjectivity
Alain Samson, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] - T. +33 4 68 49 44 17
The mouth, nose or brain... wine for all the senses
Thierry Thomas-Danguin, Centre for Taste, Food and Nutrition Sciences
(Inra, CNRS, Université de Bourgogne), Inra-Dijon
[email protected] - T. +33 3 80 69 30 84
Fruity notes that are difficult to perceive
Do experts have special noses?
Philippe Darriet, Joint Research Unit for Oenology
(ISVV-Université Bordeaux Segalen-INRA), Inra-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 57 58 60
6 It’s in the bouquet!
The softness of dry wines
Philippe Darriet, Joint Research Unit for Oenology
(ISVV-Université Bordeaux Segalen-INRA), Inra-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 57 58 60
Understanding astringency
Veronique Cheynier, Sciences for Oenology Joint Research Unit
(INRA-Montpellier SupAgro-Université Montpellier I), INRA-Montpellier
[email protected] - T. +33 4 99 61 22 98
7 Wines of every hue
La vie en rosé
Veronique Cheynier, Sciences for Oenology Joint Research Unit
(INRA-Montpellier SupAgro-Université Montpellier I), INRA-Montpellier
[email protected] - T. +33 4 99 61 22 98
8/9 AOC wines, a family resemblance
Soil does not make a terroir. Predicting the evolution of appellations
Yves Cadot, Grapevine and Wine Experimental Unit, INRA-Angers-Nantes
[email protected] - T. +33 2 41 22 56 63
And why are consumers attached to AOC wines?
Eric Giraud-Héraud, Nutrition and Social Sciences Research Unit, INRA-Versailles-Grignon
[email protected] - T. +33 1 49 59 69 33
26
News Office I +33 1 42 75 91 69 I [email protected]
10 Spotlight on prices
Sebastien Lecocq, Nutrition and Social Sciences Research Unit,
INRA-Versailles-Grignon
[email protected] - T. +33 1 49 59 69 42
11/12
Grapes that are good enough to eat
Polyphenols under the microscope
Agnes Ageorges, Sciences for Oenology Joint Research Unit
(INRA-Montpellier SupAgro-Universite Montpellier I), INRA-Montpellier
[email protected] T. +33 4 99 61 27 56
Step by step cuisine: Wöhler sauce with polyphenols!
Herve This, Joint Research Unit for Food Process Engineering
(INRA-AgroParisTech-CNAM), INRA-Jouy-en-Josas
[email protected] - T. +33 1 44 08 72 90
The secret of Pinot gris lies in its skin
Frederique Pelsy, Joint Research Unit for Grapevine Health and Wine Quality, INRA-Colmar
[email protected] - T. +33 3 89 22 49 46
Sugars and maths
Zhanwu Dai, Joint Research Unit for Ecophysiology and Grape Functional Genomics
(INRA-Bordeaux Sciences Agro-Universites Bordeaux 1 and Bordeaux Segalen),
INRA-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 57 59 22
Primary aromas
Philippe Hugueney, Joint Research Unit for Grapevine Health and Wine Quality
(INRA-Universite de Strasbourg), INRA-Colmar
[email protected] - T. +33 3 89 22 49 74
13/15
Innovations from harvest to the bottle
A new concept: ”precision oenology“,
Dynamic grape crushing, A hot flash on the harvest,
Continuous juice production, While wine macerates...
Magali Bes, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] - T. +33 4 68 49 44 05
Automated fermentation
Jean-Marie Sablayrolles, Sciences for Oenology Joint Research Unit
(INRA-Montpellier SupAgro-Universite Montpellier I), INRA-Montpellier
[email protected] - T. +33 4 99 61 25 00
The largest collection of vine varieties in the world is held by INRA!
Thierry Lacombe, Joint Research Unit for the Genetic Improvement
and Adaptation of Mediterranean and Tropical Plants, INRA-Montpellier
[email protected] - T. +33 4 99 61 22 53
16/17
These yeasts that can make good wine
Yeasts and genes
Sylvie Dequin, Sciences for Oenology Joint Research Unit
(INRA-Montpellier SupAgro-Universite Montpellier I), INRA-Montpellier
[email protected] - T. +33 4 99 61 25 28
Winemaking wasps!
Jean-Luc Legras, Sciences for Oenology Joint Research Unit
(INRA-Montpellier SupAgro-Universite Montpellier I), INRA-Montpellier
[email protected] - T. +33 4 99 61 31 70
Secondary aromas and aroma precursors
Jean-Michel Salmon, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] – T. +33 4 99 61 25 05
and Philippe Darriet, Joint Research Unit for Oenology
(ISVV-Université Bordeaux Segalen-INRA), INRA-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 57 58 60
18/21
New winemaking practices
Through the membrane
Jean-Louis Escudier, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] - T. +33 4 68 49 44 01
Pulsed electric fields
Philippe Darriet, Joint Research Unit for Oenology
(ISVV-Université Bordeaux Segalen-INRA), INRA-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 57 58 60
Clouds in white wines
François-Xavier Sauvage, Sciences for Oenology Joint Research Unit
(INRA-Montpellier SupAgro-Universite Montpellier I), INRA-Montpellier
[email protected] - T. +33 4 99 61 25 01
The control of dissolved gases
Jean-Claude Vidal, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] - T. +33 4 68 49 74 00
Wine and health
Nutrinet Study, Paule Martel, Joint Research Unit for Nutritional Epidemiology
(INRA-INSERM-CNAM-Université Paris 13), INRA-Jouy-en-Josas
[email protected] - T. +33 1 34 65 22 54
22 Climate change: which wines for tomorrow?
Joint coordinators of the Laccave projec: Jean-Marc Touzard,
Joint Research Unit for Innovation and Development in Agriculture
and the Agri-Food Sector (INRA-SupAgro-CIRAD), INRA-Montpellier
[email protected] - T. +33 4 99 61 24 65
and Nathalie Ollat, Joint Research Unit for Ecophysiology and Grape Functional
Genomics (INRA-Bordeaux Sciences Agro-Universites Bordeaux 1 and Bordeaux Segalen),
INRA-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 57 59 30
22
It’s trendy!
Wine with a lower alcohol content
Magali Bes, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] - T. +33 4 68 49 44 05
Di@gnoplant
Denis Thiery, Joint Research Unit for Vine Health and Agroecology
(INRA-Bordeaux Sciences Agro), INRA-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 12 26 39
New resistant varieties
Didier Merdinoglu, Joint Research Unit for Grapevine Health and Wine Quality
(INRA-Universite de Strasbourg), INRA-Colmar
[email protected] - T. +33 3 89 22 49 48
And what about organic wine?
Jean-Michel Salmon, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] - T. +33 4 99 61 25 05
Château Couhins, a cru classé Graves wine for sustainable viticulture
Dominique Forget, Bordeaux Viticultural Experimental Farm, INRA-Bordeaux-Aquitaine
[email protected] - T. +33 5 56 30 77 61
Other contacts:
Gerard Barbeau, Director, Grapevine and Wine Experimental Unit, INRA-Angers-Nantes
[email protected] - T. +33 2 41 22 56 72
Serge Delrot, Director, Joint Research Unit for Ecophysiology and Grape Functional
Genomics (INRA-Bordeaux Sciences Agro-Universites Bordeaux 1 and Bordeaux Segalen),
INRA-Bordeaux-Aquitaine
[email protected] - T. +33 5 57 57 59 00
Hernan Ojeda, Director, Pech Rouge Experimental Unit, INRA-Montpellier
[email protected] - T. +33 4 68 49 44 08
Patrick Bertuzzi, Director, Agroclim, INRA-PACA
[email protected] - T. +33 4 32 72 22 25
Jean-Philippe Steyer, Director, Laboratory for Environmental Biotechnology,
INRA-Montpellier
[email protected] - T. +33 4 68 42 51 78
147, rue de l’Université
75338 Paris Cedex 07
France
Tél. : + 33 1 42 75 91 86
Fax : + 33 1 42 75 91 72
www.inra.fr
Creation and production: Pascale Inzerillo - Inra-Micom
Cover pictures: ©Fotolia