Wine Production

4.1 Viticulture
4.2 Vinification
4.3 Wine Care

Wine production can be divided into 3 stages
4.1 Viticulture
4.2 Vinification
4.3 Wine Care

Wine is an alcoholic beverage made from fermented grapes or other fruits. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, water, or other nutrients

Wines made from fruits besides grapes are usually named after the fruit from which they are produced (for example, pomegranate wine, apple wine and elderberry wine) and are generically called fruit wine.

For the purpose of this study, wine would mean, the drink made from Grapes.

Wine making can be broken down into three stages as illustrated in Figure 1.1 below.

Figure Wine making

4.1 Viticulture
Viticulture is the science, production and study of grapes that deals with the events that occur in the vineyard.

Duties of the viticulturist include: monitoring and controlling pests and diseases, fertilizing, irrigation, canopy management, monitoring fruit development and characteristics, deciding when to harvest and vine pruning during the winter months. Viticulturists are often intimately involved with winemakers, because vineyard management and the resulting grape characteristics provide the basis from which winemaking can begin.

The grape vine is the source of all wine. Reaching the highest level of quality in wine is only possible by starting with the highest quality fruit. Maximizing fruit quality from any vineyard site can be a lengthy process, because the end results are revealed only after several seasons of comparison.

4.1.1 Vine Species

Vitis (grapevines) is a genus of about 60 species of vining plants in the flowering plant family Vitaceae. The genus is made up of species predominantly from the Northern hemisphere. It is economically important as the source of grapes, both for direct consumption of the fruit and for fermentation to produce wine.

The exact number of species is not certain, with species in Asia in particular being poorly defined. Estimates range from 40 to more than 60. Some of the more notable ones include:

Vitis Vinifera, the European grapevine. Native to the Mediterranean and Central Asia.

Vitis Labrusca, the Fox grapevine, sometimes used for wine. Native to the Eastern United States and Canada.

Vitis Aestivalis, the Summer Grape, native to the Eastern United States, especially the Southeastern United States.

Vitis Coignetiae Crimson Glory Vine, a species from East Asia grown as an ornamental plant for its crimson autumn foliage.

Vitis Amurensis, native to the Asian continent, includes parts of Siberia and China.

There are many cultivars of grapevines; most are cultivars of Vitis vinifera. Hybrid grapes also exist, and these are primarily crosses between Vitis vinifera and one or more of Vitis labrusca, Vitis riparia or Vitis aestivalis. Hybrids tend to be less susceptible to frost and disease (notably phylloxera), but wine from some hybrids may have a little of the characteristic "foxy" taste of Vitis labrusca.

Grapes

The Grape vine belongs to the Ampelidaceace family. It is only the genus vitis (vine) that is usually used by the wine maker.
There are 5 families of vines kept in the nursery for 12 to 14 months. They are then transplanted to the Vineyards for the first 5 years. Fruits are not allowed to be on the vine because the vine is allowed to nourish and get stronger. If the vine survies in the poorest soil for the first two years it will even survive in droughts. Vineyards are grown on mountain slopes so that -

1. Water doesn’t accumulate.

2. They also grow near lakes and river because of the reflection of sunlight.

3. The vineyards are mostly grown in the North South direction and never in the East West direction (as the ground is not heated enough due to the sun’s shadow).

The Vine creeper is a delicate creeper with a life span of 20 years. Vine is grown from a shoot i.e. by grafting method so that the same grapes are grown.

Soil: It can grow in any type of soil and will survive in the poorest of the soil.

Climate: The required climate for the development of vines is :

i. Winter: It should be short, cold but not severe.

ii. Spring: It should be mild with good supply of rain.

iii. Summer: It should be long, hot with mild showers and plenty of morning and evening dew.

Temperature: The growth and every other functions of vine is link to the ground temperature of about 10 degree Celsius an optimum temperature for the vine 25 degree Celsius to 28 degree Celsius. The relative humidity should be about 60 % to 80%. Enough sunlight gives health to the grapes and to develop sugar.

Structure of grape: -

Fig. 4.2 Composition of Grape

The grape is made of stalk, skin, pips and pulp.

Stalk: It imparts tannic acid to wine. It is mostly used in the making of florescent red wine (not used when making white wine and light wines) Tannin is necessary as it acts as a preservative and anti oxidant. It is recognized on the palate by its tongue furring properties.

Skin : The outer skin or cuticle has a whitish downy or cloudy coat known as the “bloom “. This waxy substance contains wild yeast and wine yeast and millions of minute enzymes which contribute to the fermentation process. The inside of the skin imparts colour which is extracted during fermentation.

Pips: Crushed pips impart tannic acid, oil and water. If left uncrushed they do not contribute to Vinification (Manufacturing or making wine)

Pulp: The flesh of the grapes provides the juice (must) which is essential for the fermentation. The must contains 78 to 80% water, 10 to 25% sugar, 5 to 6% acid.

Examples of white grapes:

Chardonnay
Chenin Blanc
Semillon
Sauvignon blanc
Sylvaner
Aligote
Riesling
Gewürztraminer
Pinot Grigio
Muscat

Examples of Black Grapes or Red Grapes :
Cabernet Sauvignon
Gamay
Merlot
Pinot Noir
Syrah / Shiraz
Zinfandel
Cabernet Franc
Malbec
Hermitage

4.1.2 Climatic conditions required

Beyond establishing whether or not viticulture can even be sustained in an area, the climatic influences of a particular area goes a long way in influencing the type of grape varieties grown in a region and the type of viticulture practices that will be used. The presence of adequate sun, heat and water are vital to the healthy growth and development of grapevines during the growing season.

The grapevine prefers the temperate climate in which it evolved, with warm, dry summers and mild winters. Winters of sustained cold kill grapevines. High humidity promotes vine disease. Tropical temperatures disrupt the normal vine cycle of winter dormancy.

In addition to temperature, the amount of rainfall is another defining characteristics. On average, a grapevine needs around 28 inches (700 mm) of water for sustenance during the growing season.

In Mediterranean and many continental climates, the climate during the growing season may be quite dry and require additional irrigation. In contrast, maritime climates often suffer the opposite extreme of having too much rainfall during the growing season, which poses its own viticulture hazards [4]

Other climate factors such as wind, humidity, atmospheric pressure, sunlight as well as diurnal temperature variations which can define different climate categories, can also have pronounced influences on the viticulture of an area[5]

Grapevines are fairly adaptable plants, growing in a wide variety of soil types, from light sand to packed clay, and flourishing around the globe in the temperate bands between 20° and 50° Latitude, north or south of the Equator.

They are successfully grown in Europe, the Balkans, Asia, Mediterranean and South Africa, South Australia and New Zealand, most of North America and a good portion of South America.

Wine makers’ calendar

Month

Activity

January

The Pruning of the Vines. Vines can survive -18 C

February

Finish pruning and take cuttings for grafting. Machine preparation

March

The vines begin to emerge from dormancy. Tend to soil; aerate it and uncover bases of the vine

April

Vineyard clean up continues, stakes are checked and replaced if needed. Plant one-year-old cuttings from nursery.

May

Frost danger is high and the vines must be watched through the night. Working of the soil, weed control. Removing of unwanted suckers

June

The vines begin to flower, shoots are thinned and the best ones are tied to the wire

July

Continuous care of vines and soil. Third cultivation of soil

August

Ensure equipment is ready for harvest. Weeding and care of vines continues.

September

Vintage! Protect the grapes. Keep vines trimmed. Watch for the perfect moment to pick the grapes

October

Harvesting continues until finished. Soil is fertilized and deep ploughed

November

Place soil over base of vines to protect them against the cold. Cut off the long vine shoots

December

Ice wine – (Eis Wein in Germany)

Starting over again

4.1.3 Viticulture Methods

Viticulture is name given to grape growing. The vineyard cycle follows the seasons of the year

Winemaking falls into two stages: the growing of the grapes, vinification. Traditionally, it has been the winemaker who has gained the glory, but now one regularly hears the expression, ‘the wine is made in vineyard’. Great wine needs great grapes, which in turn require suitable soil, climate, weather and expert viticulture. However it is possible for poor weather or bad farming to result in poor grapes from sites with great potential, and grapes can also be turned into bad wine.

A vine may be planted for two reasons: to create a new vineyard or to replace an existing one. The life of vine can be long; there are century-old vines in production around the world. Some old vines produce fruit of exceptional quality, though the older it is, the less fruit a vine produces.

Before the young vines are planted, where possible, the soil should be prepared to a fine tilth. The young vines may be protected against weeds by covering the land around the vine with black plastic or against animals by an individual plastic sleeves.

How a vineyard is planted depends on a number of factors, which may, or may not, include legislation, yield and the degree of mechanism used. The density of planting might be anything from 3000 to 15,000 vines per hectare. The more dense the planting, the more the stress on the vine and, hopefully, the better the fruit.

Every vine has distinct parts;

Roots

Trunk

Cane/spur

Flower/fruit

Leaves

There are two methods of viticulture

4.1.3.1 Pruning

4.1.3.2 Training

4.1.3.1 Pruning
Pruning is removal of unwanted parts of the vine, mostly wood that is one year old, or less, in order to regulate the yield and control the vine’s shape. The main pruning usually carries out by hand, is during the vine’s dormant period in the winter. Pruning may also be used to control buds – just one factor that will ultimately affect the yield of the vine and the quality of the fruit.

Basically there are two types of pruning: spur, in which a number of short, two – or three – bud spurs are left on the vine: and cane, when one or two longer canes, each 8 – 15 buds are left.

4.1.3.2 Training
once the vines has pruned, any remaining canes will then be trained. The object is to display the foliage and the fruit. The training system will depend on the type of pruning employed. In some areas vine will be free-standing, and in others, they will be trained along wires. The vines may be trained low to benefit from reflected heat or maximum exposure to wind and sun.

There are for main systems for training vine:

Four main systems for training vines are;

Bush training or gobelet
(the vines are free standing)

The replacement cane system (guyot)
(canes are trained along lateral wires)

Cordon spur
(the trunks of the vine is developed horizontally)

Parral or pergola
(vines are trained high on pergolas, with bunches of grapes being generally head-high)

WINTER

The wine rests. Winter pruning takes place. The controls the shape and size of the vine and regulates the size of the crop.

The vineyard is tidied up, and fertilizers applied. The stake and wires are repaired and replaced if necessary. In cold regions soil is ploughed up round the base of the vine for protection against frost.

SPRING

The ground is plough again to aerated it, so that the spring warmth will simulate growth. The new vines are planted.

As new growth begins, vines are sprayed for protection against pests and diseases, and this will continue at intervals until a few weeks before the harvest.

Vines are either trained along wires (guyot style) or as individual bushes, with or without support (goblelet style)

AUTUMN

Wine making equipment is cleaned and sterilized. About 100 days after flowering, the grape is ready for harvesting.

SUMMER

As the wine comes into growth it is sprayed against pests and diseases. For the most common of these and their treatment.

The vine flower. This is a most important time, when still warm conditions are essential for a good set (i.e. successful formation of fruit from flower)

As the grapes are growing the vines are given their summer pruning. This prevents the vine putting too much energy into developing foliage at expenses of ripening the grapes.

4.1.4 Vine Diseases

Likely every plant, the vine is subject to certain pests and fungal diseases. The diseases usually attacks the vine during the growth season and, as prevention is always better than cure, most vineyards begin spraying the vine as soon as growth starts.

Pests

Hazards arising due to poor weather or unsuitable soil, vine growing can be adversely affected by a number of pests and diseases.

Phylloxera the most serious insect pest of the vine. It feeds on its roots and , in the case of European V, vinifera, will kill it. There is no known way of eradicating the lose, but its effect can be stopped by grafting the V, vinifera scion. On to American root stock.

Grape Moths’ caterpillars attack the buds in the spring and the grapes themselves later in the year. Treatment is by spraying the vine with insecticides.

Red spider mite and yellow spider mite these are most prevalent in hot, dry weather. They have become increasingly common because insecticides have killed off their neutral predators.

Birds and animals

In many vineyards region birds will consume large quantities of ripe grapes. They often learn to ignore bird-scorers. Netting is the most effective solution but is expensive. Many animals such as deer, wild boar and badgers will also eat ripe grapes. Other common enemies of the vine include deer, rabbits, birds, grape berry moths, red spiders, wasps and weeds.

Diseases -
The most serious diseases are

1. Mildew

1. Powdery mildew (oudium) – the fungus reached Europe from North America in 1850. It leaves a white deposit on new growth and on developing grapes which split and shrivel.

It is combated by spraying with sulphur at flowering time. After flowering the vines are dusted with sulphur powder.

2. Downy mildew (peronospera) – the fungus first appeared in Europe asn in 1878 and thrives in damp, humid conditions. The first signs are only, transparent patches on the leaves and if not related, the fungus will destroy the grapes.

3. grey rot (pourriture grise) – a fungus called botrytis cinerea attacks the vine in humid conditions. Covering leaves and grapes with a grey mould. It destroys colour pigments in black grapes and gives an unpleasant taste to the wine from both black and white grapes. It is controlled by using anti-rot spray.

2. Rot

Noble rot

When humid conditions in the morning are followed by heat during the rest of the day, the same fungus, botrytis cinerea, can appear in its beneficial form, noble rot or porriture noble

In this form it results in shriveled grapes with very high sugar levels. Certain white grapes with thin skin are particularly susceptible to noble rot and these include Semillon and Riesling. The great sweet wines, such as Sauternes and Trockenbeerenauslese, are made from grapes attacked by noble rot.

Having survived all the hazards of the vineyard, the grapes will complete their ripening in the autumn. This point is reached normally a hundred days after the flowering of the vine.

Black rot

It is second common rot fungus, brought on by heavy rain and affecting both the leaves and the grapes. It is treated by spreading with Bordeaux mixture.

3. Long term diseases

While rot and mildew affects the quality and quantity of grapes of one harvest, other diseases attack the vine itself, with long-term effect.

Long term fungal diseases of the vine include Eutypa dieback (dead arm). It attacks the vine wood through pruning cuts, causing part of the vine to rot and die, and greatly reducing yields, though it does not adversely affects quality. No successful treatment has yet discovered.

4.2 Vinification

Winemaking, or Vinification, is the production of wine, starting with selection of the grapes and ending with bottling the finished wine

Winemaking can be divided into two general categories: still wine production (without carbonation) and sparkling wine production (with carbonation — natural or injected).

The science of wine and winemaking is known as oenology. A person who makes wine is traditionally called a winemaker or vintner.

Vinification of Still wines are done using following process:

Stages / Steps of Vinification –

i) Harvesting

ii) De- Stalking

iii) Crushing Pressing

iv)Fermentation

v) Racking

vi)Fining and Filtration

vii) Sulphuring

viii) Maturing

ix) Bottling

x) Labeling

i) Harvesting

Harvest is the picking of the grapes and in many ways the first step in wine production. Grapes are either harvested mechanically or by hand.

The decision to harvest grapes is typically made by the winemaker and informed by the level of sugar, acid and pH of the grapes.

In the case of the wine maker wanting a sweeter wine, the grapes are left to ripen for a longer period increasing the content of sugar in them. The balance of acidity and sugar is the critical element in the grapes, which gives the taste to the finished wine.

Other factors include grape flavor and tannin development. Tannin is the flavour derived from the seeds, skin and the stalk.

ii) De- Stalking

A de-stalking machine nowadays does the removal of stalks from the grapes. Stalks have a bitter taste due to the presence of Tannin and are removed so that they do not come in contact with the juice.

iii) Crushing Pressing

Crushing is the process when gently squeezing the grapes and breaking the skins to get the “must” (fresh grape juice)

The Must is obtained by Trampling on the grapes, Balloon press, Hydraulic press and Vertical press.

Methods of crushing and pressings are:

a) Trampling

b) Balloon Press

c) Hydraulic Press

d) Vertical Press

a) Trampling

Grapes are placed in large shallow tanks and persons wearing special boots trample on the grapes, crushing them and releasing the must. This was the traditional method before automation and is now done only as Promotional or Publicity event.

b) Balloon Press

This is an expandable balloon fitting in a tank filled with grapes. The balloon is expanded and this gently crushes the grapes against the sides of the tanks releasing the must. This method is used when the wine maker wants less tannin flavour in the Must.

c) Hydraulic Press

This press has a lid on the tank, which descends hydraulically crushing the grapes in the tank and releasing the must.

d) Vertical Press

This press consists of a roller with a plate surrounding it. The grapes are crushed between the roller and plate, releasing the must.

Red wine is made from the must of red or black grapes and fermentation occurs together with the grape skins, which give the wine its color.

White wine is made with Must that is not allowed to come in contact with the skins.

Occasionally white wine is made from red grapes. The Must is extracted and there is minimal contact with the grapes' skins.

Rosé wines are either made from red grapes where the juice is allowed to stay in contact with the dark skins long enough to pick up a pinkish color, or by blending red wine and white wine. White and Rosé wines extract little of thetannins contained in the skins.

iv) Fermentation

Fermentation is the process where the natural yeast on the Grape skin acts on the sugar in the Must, converting it into ethanol and carbon-di-oxide. The carbon-di-oxide is allowed to escape out.

This fermentation is carried out in Stainless steel tanks, which are controlled thermostatically at around 60 to 80 deg. F.

The fermentation can last from 2 days up to 2 weeks. This time is determined by the tradition of the wine making house. The process of fermentation continues as long as there is sugar left in the Must, and until the alcohol percentage reaches 12% - 14%. At this level the ethanol kills the yeast in the Must and fermentation stops.

If all the sugar gets converted to alcohol by this stage the wine becomes a dry wine. If there is unconverted sugar remaining the wine is a sweeter wine. In some cases, sugar is later added to drier wines to make the sweet, during the bottling process.

v) Racking

The fermented wine is transferred to Casks in the next stage, to mature. Lees (dead yeast) collects in the wine over a period of time. The wine from this cask is removed and transferred to another cask leaving the Lees behind. This process is repeated numerous times and is what gives clarity to the wines.

vi)Fining and FiltrationFining and filtration converts the cloudy wine to a clear liquid. A gelatinous substance or fining agent such as egg whites, isinglass or gelatine is introduced into the wine.

This substance attracts all the particulate matter in the wine and settles at the bottom. The clear wine is siphoned off the top and additionally passed through fine filters to further removes any particles.

vii) Sulphuring

Some wine makers add sulphur-di-oxide to the wine as a preservative. Others leave the wine, as it is, preservative free.

viii) Maturing

Wines are matured in Oak casks and the maturing period varies greatly from region to region and for different types of wines.

Maturing makes the wine mellow and smooth and also allows for the wine to acquire a certain colour from the cask in which they mature.

This is also called “Aging a Wine”

ix) Bottling

The wine is then bottled and traditionally sealed with a cork. Today, alternative wine closures like synthetic corks and screw caps, which are becoming increasingly popular.

Some wines continue the maturing process even after bottling.

x) Labeling

Wine labels are important sources of information for the buyer since they tell the type and origin of the wine.

Certain information is ordinarily included in the wine label, such as the country of origin, grading, type of grape, style of wine, alcohol percentage, producer, bottler, or importer.

Vinification – Sparkling Wine

Méthode Champenoise (Champagne making method)

The oldest and most traditional way to make sparkling wine was supposedly developed by Dom (Pierre) Perignon, a Benedictine Monk in the Champagne district of France, born in1638, and is known as Méthode Champenoise. Therefore only the sparkling wine from this region can be called champagne

Fig.4.4 Méthode Champenoise (Traditional Champagne making)

A blend of a number of wines is used to achieve consistency year after year. The wines are assembled into a "cuvée", which just means a blend of wines.

The "liquer de tirage"(yeast and sugar) is added to the cuvée, bottled, stoppered, and laid up "en tirage" to trap the carbon dioxide gas produced by the yeast as it reacts with the sugar in the wine.

The wine is then fermented "en tirage" until the yeast has reacted with all of the sugar and produced the tiny CO2 bubbles.

At the end of this fermentation in the bottle, the wine will clear and leave a deposit of yeast. It is now ready for "riddling"

The bottles are kept in "riddling racks” in an upturned position. The process known as "remuage," is the where the yeast deposits into the neck of the bottle. This takes several weeks to several months.

The bottles are then set in a freezing brine solution to freeze the yeast sediment and form a "plug" at the neck of the bottle. This is then ejected. This process is called “disgorgement”

“Dosage” is the next step in the process. Here, sugar is added to the wine if a sweeter wine is required. Typically sparkling wine is Brut (very dry), Sec (dry), Demi Sec (semi-sweet) and Doux (sweet)

Corking is done next and a wire cage in place to prevent any possible premature de corking from the high pressure contained in the bottle.

This is the traditional method of making Champagne. This is an expensive and time-consuming method. Sparkling wines can also be made where secondary fermentation takes place in the tanks itself, or by carbonating the wine and then bottling.

4.3 Wine Care

4.3.1 Wine storage

4.3.2 Wine faults

4.3.1 Wine storage
The Place where wine is stored is known as “Cellar”. The ideal cellar conditions for the storage of wine are:

The temperature should be cool & constant. The ideal temperature is 13°C. Variation between 10°C to15°C is acceptable. Too much heat will deteriorate the wine. 50% humidity should be maintained in cellar.

The storage area should not be exposed to strong light as it can age wine prematurely as well as can cause the labels to fade.

The area should be dry & clean. Damp conditions can cause deterioration of labels & cartons.

The area should be free from any vibration, which would disturb wine.

Bottles should be kept lying on their sides, with the label uppermost. In this way, corks are kept most by contact with the wine. If a cork dries out it will shrink allowing air & bacteria to enter & spoil the wine.

4.3.2 Wine faults

Faults in wine

Faults occasionally developed in wines as it matures in the bottle. Nowadays, through improved technique and attention to detail regarding bottling and storage, faulty wine is rarity. Some of the more common causes of faulty wines are given below.

Corked wines

These are wines affected by a diseased cork through bacterial action or excessive bottle age. TCA (trichloroanisole) cause the wine to taste and smell foul. This is not to be confused with cork residue in the wine, which is harmless.

Maderisation or oxidation

This is caused by bad storage leading to too much exposer to sir, often because the cork has dried out. The color of the wine browns or darkens and the taste slightly resembles that of Madeira, hence the name. The wine tastes spoilt.

Acetification

This is caused with the wine is over exposed to the air. The vinegar microbe develops a film on the surface of the wine and acetic acid is produced, making the taste sour, resembling wine vinegar.

Tartare flake

This is the crystallisation of potassium bitartrate. These crystal like flake, sometimes seen in white wines, may cause anxiety to some customers as they spoil the appearance of the wine, which is otherwise perfect to drink. If the wine is stabilized before bottling, this condition should not occur.

Excess Sulphurdioxide

Sulphur dioxide is added to wine to preserve it and keep it healthy. Once the bottle is opened, the smell will disappear and, after a few minutes, the wine is perfectly drinkable.

Secondary fermentation

This happen when trace of sugar and yeast are left in the wine in the bottle. It leaves the wine an unpleasant, prickly taste that should not be confused with the petillant or spiritzig characteristics associated with other styles of healthy and refreshing wines.

Foreign contaminationExample includes splintered or powdered glass caused by faulty bottling machinery or reused bottles which previously held some kind of disinfectant.Hydrogen sulphide

The wine smells and tastes of rotten egg and should be thrown away.

Sediment, lees, crust or dregs

This is organic matter discarded by the wine as it matures in the cask or bottle. It can be removed by racking, fining or, in the case of bottle wine, by decanting.

Cloudiness

This is causedby suspended ma5er in wine, which disguises its true color. It may also be caused by extremes in storage temperature.

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Basics of Wine Production Process

Beverages Service
Paperback
January 2020 Edition
Author:
Dr. Deepa Prasad Venkatraman
Ulhas Chaudhari

Food & Beverage Services Practical & Techniques
Paperback
January 2020 Edition
Author:
Dr. Deepa Prasad Venkatraman
Ulhas Chaudhari