wines - an introduction (1.1 to 1.3)

8/6/2019 Wines - An Introduction (1.1 to 1.3)

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Wines:: Introduction :: Vinification :: Classification ::The chemistry of fermentation is basic to making of all alcoholic beverages. Yeast

reacts with sugar and converts the sugar into alcohol and carbon dioxide and then, if

the liquid is not protected from air, into vinegar. Alcoholic beverages are obtained

from ingredients containing sugar, for example grape juice, apple juice and pear juice.

They are also obtained from ingredients such as grains, cereals and potatoes which

have no sugar but which have sugar potential because they are rich in starch. Once the

starch is converted into fermentable sugars, mainly maltose, yeast is introduced and

fermentation begins.

Yeast There are two main categories of yeast: Natural yeast and Cultured Yeast.

NATURAL YEASTS

Innumerable yeasts, moulds and bacteria are all around floating in the air, eventually

settling on or being carried onto ripe fruit, grapes and grain husks either by insects

and more specifically by the fruit fly drosophila.

CULTURED YEASTSThese are pedigree strains of natural yeast that are cultivated in a laboratory. They are

used because they are efficient in converting sugar into alcohol and are less

susceptible to sulphur in the fermenting process. Sometimes they are added to do a

specific job because they are more reliable than natural yeasts for that particular job.

They can also be used in situations where natural yeasts have been washed away by

heavy rain or when some of the yeasts have been brushed off in transit.

There are upto a thousand varieties of yeast, but the name is normally associated with

a type of unicellular fungi called Saccharomyces of which four varieties are important

regarding production of alcohol.

1. Saccharomyces cerevisiae - Refer notes on ‘Beer’.

2. Saccharomyces carlsbergensis - Refer notes on ‘Beer’.

3. Saccharomyces apiculatus - Know as ‘wild yeasts’ or ‘starter yeasts’ in the making of

wine, although these start the fermentation they are feeble fermenters and are only

Semester iii - wines [1.1]! compilation by ashish m. dighe

BVIHMCT - Chapter 1 (1.1 to 1.3)



danger to wine. The inside of the skin imparts color which is extracted during

fermentation.

Pips - Crushed pips impart tannic acid, oils and water. If left uncrushed they do not

contribute to the vinification.

Pulp - The flesh of the grape provides juice, also know as must , which is essential for

fermentation. The must contains:

• 78-80% water;

• 10-25% sugar;

• 5-6% acids.





THE VINIFICATION PROCESS

The making of the wine encompasses :

• the pressing of the grapes;

• the treatment and fermentation of the must ;

• maturing the wine and occasionally topping it up to keep the air out.

• racking, fining and filtration to make the wine star bright:

Racking: running the clear wine off its lees or sediment from one cask to

another.

Fining: a further clarification of wine usually before bottling. A fining agent

such as isinglass is added and this attracts the sediment suspended in the wine,

causing it to coagulate and fall to the bottom of the container.

Filtration: the final clarification before bottling. It removes any remaining

suspended matter and leaves the wine healthy and star bright in appearance.• blending - compensatory or otherwise.

• bottling for further maturing or for sale.

Luck of the yearIn some years, everything in the vineyards and cellars go well, combining to produce a

wine of excellence - a vintage wine. In other years, there can be great disappointments

brought on by an excess of sun, rain, snow, frost and the dreaded hail, which will

produce either poor wine or worse.

Enemies of the vine Phylloxera -These small yellow aphids puncture

the roots of the vine and form galls on the

underside of the leaves. The larvae stick to the

roots and sucks the sap which kill the vine roots.

Once it feeds on the sap, the aphid multiples at

lightning speed to continue to lay waste the

vineyards. This affects the Vitis vinifera vinesalthough vines like Vitis rupestris are immune to

the raving aphids. The solution is to graft a

vinifera scion to a rupestris root stock.

Oidium - Known as powdery mildew, this forms patches of dusty mould on the grapes

and leaves, causing the grapes to split and shrivel. Treatment: sulphur powder.





Mildew - Mildew develops in damp areas. It is a very

common vine disease which is noticeable when yellow

patches appear o the leaves. When the leaves whither

the grapes grapes become deprived of nourishment.Treatment - Spraying with copper sulphate.

Grey rot - This can be malevolent or benevolent. In most regions and at a certain time

of year, it produces, in humid conditions, a grey mould which destroys color

pigmentation in black grapes and gives an unpleasant

taste to the wine. Treatment - Anti-rot spraying. However

the same fungus, known as Botrytis cinerea, in certain

areas produces wonderful sweet wines when conditions

are favorable.

Coulure - This happens when there is soil deficiency or

too much rain or uneven temperature. The flowers on the

vine are infertile, resulting in a disappointing yield of

grapes. Treatment - use good fertilizers.

Chlorosis - Too much limestone in the soil causes

yellowing, even death of the plant. Treatment - iron sulphate.

Pyralis, Endemis and Cochylis -These tiny butterfly moths pierce the grapes and destroy

the crop within hours. Treatment - spray with insecticides.

Frost - Especially in spring, frost stunts the formation of the buds which greatly

reduces yield. Treatment - fire, heat and spraying with water.

Hail - Hail is a particular danger, especially just before the vintage when the grape

skins are very thin and the grapes are very vulnerable. Hail can easily puncture the

skins and ruin the crop.





HOW WINE IS MADE (The Vinification Process)





RED WINE: Red wine is made from black grapes. Modern wine making calls for a

wine without too much tannic acid so the grapes are de-stemmed or include only a

small percentage of stems depending on the wine styles. The grapes are crushed in a

wine press.

The must - a combination of juice, skins and pips - is put into fermentation vats. A

small amount of sulphur dioxide is added to kill off the wild yeast and undesirable

bacteria and to protect against oxidation. The juice remains with the skin from 10 to 30

days to extract color and tannin; the lighter the color required the less time it needs

with the skins. During fermentation, the yeast transforms the sugar into alcohol and

carbon dioxide. This action also

g e n e r a t e s h e a t s o t h e

temperature has to be carefully

controlled. When ferementation

is completed most of the liquid

will be run off. This is known as

free-run wine or vin de goutte.

The remaining pulp is pressed

again, resulting in a very

dark ,tannic wine known as

press wine or vin de presse. These

a r e m a t u r e d s e p a r a t e l y ,classically in oak casks, where

they undergo malolactic fermentation. They are racked several times, leaving the lees

or sediment behind. With each racking the wine becomes clearer. Before bottling, the

wine is fined to get rid of unwanted solid particles held in suspension which cause

cloudiness. Isinglass, egg whites, gelatine, dried albumen and bentonite are used as

fining agents as they drag the dregs down to the bottom of the casks leaving behind

brilliantly clear wine. The free run wine and the pressed wine is now blended and may

be again fined or filtered or both before being bottled.

WHITE WINE: White wine can be made from white grapes or black grapes. After

pressing, the must may or may not be left with the skins. The must will usually be

treated with sulphur dioxide and then passes through a centrifuge to be cleansed of

suspended matter such as pips and skin pieces. Cultured yeast may be added and a

slow, cool fermentation takes place which lasts a month or more and gives the wine





greater intensity of flavor. After fermentation, the new wine is matured in casks for a

short time. It may be racked and fined and stored in sterilized tanks for bottling.

Sometimes a little amount of concentrated grape must is added if a sweeter wine is

desired.

White wine can also be obtained from black grapes. The grapes are pressed to separatethe clear juice from the skins. Speed is of the essence because the liquid must not

contain any dyes from skins. Some wines are matured sur lie - on the lees - which

means they are not racked or filtered before being bottled. This practice gives a greater

depth of flavor to the wine and an enhanced freshness and liveliness.

ROSÉ WINE: Made from black grapes, the must is left to macerate with the skins for

about one day or until the correct degree of coloring has been achieved.

Then the must is removed to continue fermenting at a low

temperature elsewhere. (Saignée method)

BLUSH WINE: Made from black grapes

and with the Saignée method. The skins

are in contact with the must

for only an hour or two.

The whiter the wine the

better.

AMBER WINE: It is also commonly known as orange wine. It is wine

made from white wine grape varieties that have spent some

maceration time in contact with the grape skins. Orange wines get

their name from the darker, slightly orange tinge that the white wines

receive due to their contact with the coloring pigments of the grape

skins. This winemaking style is essentially the opposite of rosé

production which involves getting red wine grapes quickly off theirskins, leaving the wine with a slightly pinkish hue.

SPARKLING WINE: Sparkling wine is a wine with significant levels of

carbon dioxide in it making it fizzy. The carbon dioxide may result from natural

fermentation, either in a bottle, as with the methodé champenoise/ methodé traditionnelle;





In a large tank designed to withstand the

pressures involved, as in Charmat process; as a

result of carbon dioxide injection ( methodé

gazifié) or using the Transfer method ( methode

tranvasement).

(As the bubbles come up to the surface of the glassthey form, what is called a champagne ‘mousse’.)

NATURAL/ ORGANIC WINE: In an ideal

natural wine, nothing is added and nothing is

taken away from the grapes, must or wine. A natural wine may include some or all of

the following features:

■ Organically grown grapes, with or without certification.

■ Dry-farmed, low-yielding vineyards.

■ Hand-picked.

■ No added sugars, no foreign yeasts, no foreign bacteria.

■ No adjustments for acidity.

■ No additives for color, mouth-feel, minerality, etc.

■ No external flavor additives, including those derived from barrels, staves, chips,

or liquid extract.

■

Minimal or no fining and filtration.■ Minimal or no added sulfites.

FORTIFIED WINE: Wines that are strengthened by the addition of alcohol, usually

brandy. This is done either during fermentation (for Port) or after fermentation (for

Sherry)

AROMATIZED WINE: Wines that are flavored and fortified. Vermouth, Dubonnet

and Punt-E-Mes are examples of aromatized wines.

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wines - an introduction (1.1 to 1.3)

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