In
viticulture
Viticulture (, "vine-growing"), viniculture (, "wine-growing"), or winegrowing is the cultivation and harvesting of grapes. It is a branch of the science of horticulture. While the native territory of ''Vitis vinifera'', the common grape vine ...
, veraison (, ) is the onset of the ripening of the grapes. The official definition of ''veraison'' is "change of color of the grape berries".
Veraison represents the transition from
berry
A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit although many pips or seeds may be present. Common examples of berries in the cul ...
growth to
berry ripening, and many changes in berry development occur at veraison.
Process
Grape berries follow a
double sigmoid growth curve. The initial phase of berry growth is a result of
cell division
Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...
and
cell expansion. As berry growth of phase I slows this is termed the lag phase. The lag phase is not a physiological growth stage, but an artificial designation between the two growth periods of grape berry development.
Post-veraison,
fruit acidity decreases due to degradation of
malic acid
Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ( ...
. The degradation of malic acid during ripening makes
tartaric acid the predominant acid; grape berries also possess a small amount of citric acid. Tartaric acid accumulates early in phase I of berry growth, while malic acid accumulates at the end of phase I berry growth.
At the same time as acidity decreases,
hexose
In chemistry, a hexose is a monosaccharide (simple sugar) with six carbon atoms. The chemical formula for all hexoses is , and their molecular weight is 180.156 g/mol.
Hexoses exist in two forms, open-chain or cyclic, that easily convert into ...
sugars are accumulated.
[ The accumulation of hexose sugars (]glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...
, fructose
Fructose (), or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and gal ...
) is associated with the development of xylem
Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...
cell discontinuities which reduce the volume of water entering the berry relative to the volume of sugar, resulting in an increase in sugar concentration. Physiologically, the sugar concentration can increase to around 25 percent via sugar development. Further increases in sugar concentration are due to dehydration of the fruit. The deposition of sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecul ...
into the berry depends on the level of leaf photosynthesis
Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...
, the number of competing sinks on the vine and sugar accumulation.
As ripening continues, the fruit becomes attractive to animals due to changes in aroma from acidic to sweet with fruitiness. As ripening occurs, herbaceous aromas (e.g. methoxypyrazines) are degraded. It is unknown whether the degradation of herbaceous aromas allows fruit aromas to be detected, or if fruity aromas develop later in berry ripening.
The berry also changes in color, presumably because chlorophyll
Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...
is broken down. In white cultivars, carotenoids
Carotenoids () are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and Fungus, fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips ...
are formed, while in red cultivars, anthocyanin
Anthocyanins (), also called anthocyans, are solubility, water-soluble vacuole, vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart named a chemical compou ...
s and xanthophylls are formed.[
The trigger of veraison is unknown, but may signify the seed reaching maturity, an unlikely signal, however, because seedless berries also proceed through veraison.
]
Other uses
Fête de la Véraison is a medieval festival held in the famous winemaking village of Châteauneuf-du-Pape.
See also
* Annual growth cycle of grapevines
References
External links
Site showing images of Veraison
{{Viticulture
Viticulture