Wine production by Afrah Aamer

-A Project by Afrah Aamer

Contents INTRODUCTION ............................................................................................................................................. 4 OVERVIEW..................................................................................................................................................... 4 VITICULTURE ................................................................................................................................................. 5 GREEN REVOLUTION ..................................................................................................................................... 5 VINEYARD REVOLUTION ............................................................................................................................... 5 APPROACHES TO VITICULTURE ..................................................................................................................... 5 Conventional Viticulture ....................................................................................................................... 5 La lutte raisonée .................................................................................................................................. 5 Organic viticulture................................................................................................................................. 6 Biodynamic viticulture .......................................................................................................................... 6 OVERVIEW..................................................................................................................................................... 6 Before fermentation ............................................................................................................................. 6 Fermentation ........................................................................................................................................ 6 After fermentation ................................................................................................................................ 6 HARVESTING ................................................................................................................................................. 6 Timing.................................................................................................................................................... 6 Method ................................................................................................................................................. 7 CRUSHING AND PRESSING ............................................................................................................................ 7 Maceration ............................................................................................................................................ 7 Carbonic maceration ............................................................................................................................. 7 FERMENTATION ............................................................................................................................................ 8 YEASTS........................................................................................................................................................... 9 SUGARS ....................................................................................................................................................... 10 MALOLACCTIC FERMENTATION .................................................................................................................. 10 AFTER FERMENTATION ............................................................................................................................... 11 MATURATION.............................................................................................................................................. 11 FINING ......................................................................................................................................................... 11 FILTERATION ............................................................................................................................................... 11 ADDING SULPHUR TO WINE ....................................................................................................................... 11 UNSULPHURED WINES ................................................................................................................................ 11 SULPHUR IN THE WINERY ........................................................................................................................... 12 ABOUT OXIDATION ..................................................................................................................................... 12

USES ............................................................................................................................................................ 12 SULPHITES IN WINE..................................................................................................................................... 12 WHAT ARE THE HEALTH IMPLICATIONS?.................................................................................................... 13 FILTERATION ............................................................................................................................................... 13 BOTTLING .................................................................................................................................................... 13 REFRENCES .................................................................................................................................................. 13

INTRODUCTION Winemaking is the production of wine, it starts by the selection of the grapes and ends by the bottling of the finished wine. Most wines are made from grapes but it may also be made from other fruits and plants. The science of wine and winemaking is known as oenology. Oenology is the science and study of all aspects of wine and winemaking excluding the process of vine-growing and grape-harvesting, which is a subfield called viticulture. A person who makes wine is traditionally and commonly called a winemaker or also known as a vintner.

OVERVIEW Once the grapes have been picked, they are transported to the winery, then certain preparatory steps must be taken before the actual winemaking can begin. Once the grapes are taken into a winery, they are made prepared for primary ferment. Cleanliness and sanitation are essential for good winemaking, as some bacteria could cause disastrous results. White wine and red wine diverge at this stage, i.e. after de-stemming and crushing.

ed wine is made from the pulp or must of the red or black grapes. Fermentation then occurs along with the skins of the grapes, which give the colour of the wine. White wine is made to ferment the extract which is first made by pressing the crushed grapes to extract a juice; the skins are removed so they play no role further in the winemaking process. Infrequently white wine is made from red grapes; this is done by extracting their juice with least contact with the grapes' skins. RosĂŠ wines are either made from red grapes where the juice is allowed to stay in contact with the dark skins long enough to collect a rose-pink color or also by blending red wine and white wine together. White and rosĂŠ wines extract little of the tannins contained in the skins. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of an unripened fruit or red wine.

Figure 1 the process of making of red and white wine Designed by Afrah Aamer 4

VITICULTURE Viticulture is the cultivation of grapes. It's been practiced for around 7,000 years, and has radically changed in the last 50 years.

GREEN REVOLUTION Along with all other forms of agriculture, grape-vine-growing has undertaken a chemical as well as the technological revolution beginning from the Second World War. During the time of 1950 and 1990, without a significant increase in the total area of agricultural land, world-wide agricultural yields were tripled. But the increases have come at a price. Chemically controlled agriculture, damages the fertility of the soil, and it also releases large quantities of toxic chemicals into the ecosystem, and promotes resistance in the pests it seeks to control. In addition to that, it is also detrimental to the quality of the crop which is harvested. When the unconventional occurring occurs as a famine, this is a price worth paying.

VINEYARD REVOLUTION In viticulture, the alternative is not famine. Wine is a luxurious product made out of a crop which grows best on the land which is unsuitable for the production of food. There is no shortage of such sites and locations. The accomplishment of the chemical viticulture has been performed and achieved only for purely commercial purposes. It is not really hard to see what pushes it. The interests of the grower-To guarantee his harvest, increase his yields, and not have to work as hard. The interests of agro-chemical companies-To sell as much of their product as possible, year after year. The indifference of the consumer-As to how the wine he drinks is produced and what it tastes like. It has been observed that many growers who have embraced the chemical approach earlier, have now become clear that it was only their short-term interests. But as long as most consumers are prepared to accept a bland, industrially-manufactured product, that is what most wine will be like.

APPROACHES TO VITICULTURE For as long as there have been chemicals in the vineyard, there have also been those who rejected their use.

Conventional Viticulture Conventional cultivators control the life of the vineyard with a progressions or series of toxic sprays. Their aim is to keep the vine 'healthy' by killing any substance that might be proved harmful to it.

La lutte raisonĂŠe La lutte raisonĂŠe means 'the purposeful struggle'. Growers who practice this kind of viticulture claim to use chemicals less often and less aggressively than conventional growers, but are not subject to any kinds of legal controls.

Organic viticulture The Viticulture in which the use of chemicals in organic farming is strictly controlled by law. Almost none of what is available to the conventional grower is permitted.

Biodynamic viticulture Biodynamic viticulture is a form of organic agriculture, which is based on the ideas of the Austrian philosopher Rudolph Steiner. He explained the involvement of a complex system of herbal sprays and composting techniques known as 'preparations'.

OVERVIEW The center to the process is the process fermentation, which involves the conversion of the grapesâ&#x20AC;&#x2122; natural sugars into alcohol and carbon dioxide. Winemaking can be roughly divided into what happens before, during, and after fermentation. Here is a brief sketch of the most important points.

Before fermentation Harvesting-Best done by hand, usually done by machine. Crushing/pressing-The skin of the grapes is torn and removed to release the sugary juices, and then exposing them to the yeasts for fermentation.

Fermentation There are generally two types of fermentation in wine, which may or may not take place simultaneously. Primary fermentation-The conversion of the grapesâ&#x20AC;&#x2122; stored sugars into alchohol and carbon dioxide. It is carried out by yeasts. Malolactic fermentation-The conversion of malic acid into lactic acid and carbon dioxide. This changes the taste of the wine but does not affect its alcohol content.

After fermentation Maturing- Wines may be left to mature in barrels for as much as about three years before being bottled for release. Clarification-Conventional wines can be cleaned up in a variety of ways, and sterile filtered before bottling.

Figure 2 Wine fermentation tanks

Bottling-It is almost universal practice to add sulphur dioxide at this point, to prevent or retard changes in the bottle. Some winemakers will mature their wines further in the bottle before they are sold.

HARVESTING Timing Choosing the right moment and time to harvest the grapes is essential to enhance the wine quality. A great wine can only be made from ripe grapes. But the longer it is left on the vine, the greater the chance that the crop will be damaged, either by cold or diseases. Conventional winemakers

get round this by picking early, before the grapes are ripe, and attempting to correct for it in the winery. For natural winemakers it's a question of instinct, bravado and nerve.

Method To make a good natural wine, it is preferred that the grapes must be hand-picked. There are several reasons for this: Hand-picking is selective and also unripe or damaged grapes can be rejected. Harvesting machines damage grapes. They work by smacking the vine foliage with fiberglass rods and catching the grapes as they fall. Harvesting machines are large and in order to accommodate them, vines have to be widely spaced and trellised in a certain way. These are both negotiations which damage the wine quality. As the grapes are picked, the fruit is in a must to be collected into small containers, to avoid being crushed by the force of its own weight, and it is then taken to the winery as quickly as possible.

CRUSHING AND PRESSING These are not the same thing, but are often confused with each other; crushing grapes means the breaking of their skins to release the juices so that the fermentation process can begin. Crushed grapes are a sugary pulp of juice and skins and is called the must. Pressing is the removal of the skins and any other solid matter from the must. The juice is just pressed out, just like as you might squeeze an orange, and the skins are thrown away. It is not necessary to press the must for the fermentation to begin.

Maceration The period between crushing and pressing, when the juice is still in contact with the skins, is called maceration. The skins may be removed before, during, or even after fermentation. For dark red wines, maceration takes longer than for lighter reds. White wines will be pressed Figure 3 Anatomy of Grapes and crushed simultaneously. The winemaker must also choose when to destem the fruit. Leaving the stems in during maceration gives a more tannic, astringent wine.

Carbonic maceration Carbonic maceration takes place whenever, whole bunches of grapes are held in carbon dioxide. Within the grapes, small amounts of sugar are converted into alcohol, without the need for yeasts.

Eventually this causes the grapes to burst out, so that normal fermentation can begin. It produces a light, and fruity red wine and is most famously used in Beaujolais and the Loire.

FERMENTATION The process of fermentation in winemaking turns grape juice into an alcoholic beverage. During fermentation, yeasts transform sugars present in the juice into ethanol and carbon dioxide. Even a very complex wine is only alcoholic grape juice. In winemaking, the temperature and speed of fermentation Figure 4 Fermenting Must are important considerations. The alcohol released, is produced by a process called fermentation. Fermentation requires two things: sugars and yeasts. A ripe organic grape is full of natural sugars and there are wild yeasts living on its skin. As soon as the skin of the grape is broken, fermentation can begin. To make wine, all the winemaker has to do is to collect his grapes and get them crushed, releasing the sugary juice and then exposing it to the yeasts. Fermentation will continue until all the sugar has been turned into alcohol or the level of alcohol in the extract reaches around 15%, whichever is sooner. At around 15% alcohol, the yeasts will die naturally and any leftover sugars will stay in the wine.

Figure 5 Pressing and Fermentation of Grapes

YEASTS The natural wine is fermented only with the wild yeasts which are native to its terroir. Yeast strains vary widely from place to place and they contribute considerably to the aroma of the finished wine. The yeasts indigenous to a particular area and are an important part of what gives its wines their character.

Figure 6 the process of making Red Wine

Usually grown grapes have very little or no wild yeast living on their skin. The winemaker will kill whatever yeast remains with sulphur dioxide, and he then reseeds the grapes with a single strain of commercially produced yeast. Wines which are fermented in this way will have less personality, all using the same few commercial yeast strains, and are less an expression of their terroir. This is

one of the reasons that they taste so similar. They are also less complex, as each of the many wild yeasts present on an organic grape will contribute something to the finished wine.

SUGARS The level of alcohol obtained in the finished wine is determined by the level of sugar present in the grapes from which it is made. More sugar means there is more for the yeast to convert into alcohol. Figure 7 the production of ethanol with yeast Grapes grown further north see less sun and therefore contain less stored sugar than those grown in the south. Traditionally, northern wines contain a lower level of alcohol. A natural wine is fermented only with its own sugars. Chaptalization is an efficient method of boosting the level of alcohol in the finished wine by adding sugar to the juice during fermentation process. The technique is named after Jean Antoine Chaptal. He was Napoleon's minister for agriculture, who is said to have invented the process.

MALOLACCTIC FERMENTATION Malolactic fermentation occurs when the lactic acid bacteria metabolizes malic acid and produce lactic acid and carbon dioxide. This process is either carried out as an intentional procedure, in which specially cultivated strains of such bacteria are introduced into the maturing wine, or it can happen by chance if uncultivated lactic acid bacteria are present. Malolactic fermentation can improve the taste of wine that has high levels of malic acid, because malic acid, in higher concentration, generally causes an unpleasant harsh and bitter taste sensation, whereas lactic acid is gentler and less sour. Lactic acid is an acid which is found in dairy products. Malolactic fermentation usually results in an increase on the pH of the wine. Malolactic fermentation is a secondary process involving bacterial conversion, which may follow or overlap with the primary fermentation. Harsher tasting malic acid is converted into softer, and less acidic, lactic acid. Carbon dioxide is also produced. In practical terms this means a reduction in the acidity of the wine and an increase in its complexity. The level of alcohol is unaffected. Like primary fermentation, malolactic fermentation can be induced by the introduction of cultured bacteria, or suppressed with sulphur dioxide. If a wine is bottled speedily, it may take place inside the bottle. One reason SO2 is used at bottling is to prevent this. A natural winemaker has to wait for the malolactic fermentation process to finish naturally before he can bottle his wine.

AFTER FERMENTATION Some wines are ready to drink immediately after fermentation, while the others are matured in oak barrels for anything up to three or four years before bottling. Conventional wines will be heavily filtered and dosed with sulphur dioxide before being put into the bottle.

MATURATION The age of the wood in which a wine is matured affects its flavor dramatically. Old oak will add subtly to a wine, new oak will give it a strongly woody, vanilla taste and smell. Heavily oaked wines are currently very popular. Most expensive wines are matured in 'one hundred percent new oak barrels' and proud of it. One reason for this is that it is a good way to disguise a bad wine. The oak overpowers the flavor of the grapes and their quality becomes less important. An oak effect can be achieved without the need for maturation by adding chips of wood to the wine directly, during fermentation. This is not uncommon.

FINING Fining is a way of clarifying wine by passing a foreign substance through it. The fining agent sinks slowly down from the top of the vat, collecting any particles as it goes. Most natural wines are not fined at all. Those that are will only be fined with organic egg-white. Fining agents used in conventional winemaking include in conbentonite, silicon dioxide gel, potassium Ferro cyanide, metatarcic acid, and isinglass.

FILTERATION Conventional wines are filtered to remove all bacterial life before they are bottled. Not only is this unnecessary, it damages the flavor of the wine. A natural wine will either have been subject to a very light filtration, or no filtration at all. Even a filtered natural wine may not be limpid. Sterile wine tastes sterile. A natural wine is a living thing, containing living bacteria, and it tastes alive.

ADDING SULPHUR TO WINE Sulphur dioxide (SO2) is the most widely used and controversial additive in winemaking. Its main functions include to inhibit or kill unwanted yeasts and bacteria, and to protect wine from oxidation. SO2 is added at several points in the process of conventional vinification and is present in the finished wine in the form of sulphites. Sulphites occur naturally in all living things and are present in small quantities even in unsulphured wines. They are capable of causing potentially fatal allergic reactions. HISTORY

UNSULPHURED WINES Most winemakers would confess that it is not possible to make good wine without sulphur dioxide. This is not true. But the risks are such that very few winemakers are prepared to take them. The myth that sulphur dioxide is always necessary needs to be fought. But we also recognise that in certain circumstances sulphur dioxide is the only option. Used at bottling in homeopathic doses it

does little or no damage to the flavour of the wine, and can help to protect it from being mishandled. There are some very natural winemakers who work in this way.

SULPHUR IN THE WINERY Sulphur dioxide (SO2) is the most extensively used and controversial preservative in winemaking. Its main functions are to inhibit or kill unwanted yeasts and bacteria, and to protect wine from oxidation.

ABOUT OXIDATION Oxidation is the reaction of wine with oxygen. It can alter its colour and odour, tending to make wines darker and dryer, and is often dismissed as a fault. Excessive oxidation does ruin wine. But controlled oxidisation can add complexity, and is crucial to certain styles.It is an important part of the ageing process. This is why most wine authorities will tell you that it is impossible to make a wine which ages well without using sulphur dioxide. The SO2 drastically inhibits the process of oxidation. Whether what you have is a wine which ages well, or merely one which ages is slowly, is a moot point.

USES There are four points at which sulphur dioxide is commonly used in conventional winemaking, although the winemaker may choose to make further additions if he is feeling nervous. Picking- It is applied in the form of metabisulfite to inhibit the action of wild yeasts and prevent the process of oxidation. It means the grapes don't have to be rushed to the winery. Crushing- It is to prevent fermentation from the beginning with wild yeasts before the cultured yeasts that can be added. Cultured yeasts are bred to be more resistant to SO2. Fermentation- At any point during fermentation, but most commonly at the end to stop or prevent malolactic fermentation. A natural winemaker has to wait for the malo to finish naturally. Bottling- To prevent oxidation, or any other microbial action, in the bottled wine. In sweet wines there is the danger that fermentation will restart. A natural winemaker would only ever use sulphur dioxide at bottling, only in white wines, and only in very small quantities. Many natural winemakers use none at all.

SULPHITES IN WINE All wines contain sulphur dioxide in various forms, collectively known as sulphites. Even in completely unsulphured wine it is present at concentrations of up to 10 milligrams per litre. Commercially-made wines contain from ten to twenty times that amount. There are three reasons you might not want sulphur dioxide added to your wine. Taste- Sulphur dioxide has an unpleasant smell, like that of a struck match, detectable at very low concentrations.

Health- Sulphur dioxide can cause potentially fatal allergic reactions and has been linked with numerous other health problems, including hangover. Principle- Adding sulphur dioxide breaks the principle of naturalness in wine.

WHAT ARE THE HEALTH IMPLICATIONS? The World Health Organisation recommends a maximum daily intake of 0.7mg of sulphur dioxide per kilogram of bodyweight. For a man of average weight this is less than a third of a bottle of a white wine with a concentration of 200 mg/l (the EU limit for dry white wine is 210mg/l). Regular consumption of conventional wines means regularly exceeding the RDA of sulphur dioxide by a large margin. Wine is not the only product with high levels of SO2. More specifically, sulphur dioxide can cause allergic reactions in some people. It is dangerous for asthmatics even at very low levels. Sulphur dioxide contributes significantly to hangovers. Heavy drinkers who also have to get up in the morning would be advised to stick to natural wine.

FILTERATION Filtration in winemaking is used to accomplish two objectives, clarification and microbial stabilization. In clarification, large particles that affect the visual appearance of the wine are removed. In microbial stabilization, organisms that affect the stability of the wine are removed therefore reducing the likelihood of re-fermentation or spoilage. The process of clarification is concerned with the removal of particles; those larger than 5–10 micrometers for coarse polishing, particles larger than 1–4 micrometers for clarifying or polishing. Microbial stabilization requires a filtration of at least 0.65 micrometers. However, filtration at this level may lighten a wine's color and body. Microbial stabilization does not imply sterility. It simply means that a significant amount of yeast and bacteria have been removed. Clarification of the wine can take place naturally by putting the wine into refrigeration at 35°F (2°C). The wine takes about a month to settle and it is clear. No chemicals are needed.

BOTTLING A final dose of sulfite is added to help preserve the wine and prevent unwanted fermentation in the bottle. The wine bottles then are traditionally sealed with a cork, although alternative wine closures such as synthetic corks and screw caps, which are less subject to cork taint, are becoming increasingly popular. The final step is adding a capsule to the top of the bottle which is then heated for a tight seal.

REFRENCES Heather Barr, 2000 (Accessed on 29/4/2014) http://www.whitman.edu/environmental_studies/WWRB/winemaking.htm Nil, 2014 (Accessed on 1/4/2014) http://en.wikipedia.org/wiki/Fermentation_in_winemaking Nil, 2014 (Accessed on 3/4/2014) http://www.bing.com/images/search?q=wine&go=&qs=ds&form=QBLH&filt=all