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The ultimate guide to winemaking

An Argentine winemaker once said that winemaking was 50% science and 50% emotion. New Zealand winemaker Paul Pujol replied that in his opinion it was 1% art, 1% science and 98% cleaning!

The Ultimate Guide to Winemaking

Whichever way one looks at it, the art, or craft, of making grapes into good wine (the adjective is all important, as much of the world's wine production is low-quality and industrial) is extremely hard work. This article shines a light on the process from vineyard to bottle.

Do Winemakers Even Exist? A Pause For Thought

Of course grapes could not be turned into good wine without man, but it is worth pausing briefly on the fact that neither the French, Spanish, Italian or German languages have a word for 'winemaker'.

What this seemingly peculiar fact shows is that that the act of making wine is entwined heavily with the philosophy of the person doing it. The French use the word vigneron, which is best translated as 'wine grower.' In doing so, a belief is being expressed: that it is nature that makes wine, not man.

Paul Draper: 'Wine Grower'

Paul Draper
Paul Draper

Ridge Vineyards make some of the most subtle, elegant and highly prized wines in California, and indeed the world. Its legendary former CEO, Paul Draper, also preferred to use the term 'wine grower', rather than 'winemaker', to describe the craft: 'My aim is to take these pieces of ground and allow them to express themselves. What I demand of a great wine is that it reflects nature, not the hand of the winemaker; it has to have that connection to the earth.'

Many others, however, are less abashed about using the word 'winemaker' to describe what they do. All this goes to show that winemaking at its highest level can be as philosophically as it is scientifically complex.

Without further ado then, let's look at how the winemaking, or wine growing, process begins: the grapes themselves.

The Grapes

The potential of the finished wine is found in the juice and skins of the grapes from the vineyard.

The raw materials with which the winemaker works have to be healthy and balanced in order for the task to be worth undertaking in the first place: a mantra many winemakers will tell you is that it is possible to make bad wine from good grapes, but impossible to make good wine from bad grapes.

Chardonnay Grapes
Chardonnay Grapes


The harvest is the result of a year of hard work (to ensure the grapes are given all they need to ripen healthily) and crossing appendages for the prerequisite good weather.

Provided all has gone well until now, deciding when to pick is the most important decision of all. Timing is all important, and the weather is still capable of ruining everything up until the very last minute.

The decision will be made when the grower is satisfied the grapes have attained physiological ripeness - that is to say, just the right balance of sugar, acidity and flavour - or when the caprice of nature means that picking must be done before bad weather comes.

Grapes are either hand picked by teams of workers or harvested by machine. Anyone who has undertaken a harvest will know how difficult and rigorous the hand-picking process is. Normally it involves spending long periods of time stooping and moving slowly through row after row of vines - not recommended for bad backs.

Machine harvesting is quicker, but opinion is divided as to whether the resultant wine is as good. Winemakers often have strong opinions about the relative merits of each method for different grape varieties and sites.

Joel Peterson

Joel Peterson
Joel Peterson

Another legend of the California wine industry, Joel's early endeavours at Ravenswood are a source of some fantastic stories; including an early vintage that was almost doomed before the grapes even made the winery. A pothole in the road sent four tons of Dry Creek Zinfandel off the truck transporting them from the vineyard. Traffic was suspended as a team of friends was called to help scrape up the grapes. The wine was made and, according to Joel, praised by critics for its 'complex, tarry quality'!

Into the Winery

The grapes' journey from sorting table to bottle varies considerably depending on the colour and type of wine being made. The sorting table, or selection table, is a conveyor belt along which the grapes pass, under several pairs of watchful eyes and careful hands, spotting and discarding any rotten or unripe grapes, as well as leaves and any other debris that has made it out of the vineyard.

The sorting table at Mendel, Argentina
The sorting table at Mendel, Argentina

Stems may also be removed here, though some makers of red wines prefer to leave the bunches of grapes intact for the fermentation, stems and all. Whole-bunch fermentation can in some cases produce more characterful wine (it is a technique favoured by several great Burgundy domaines for their pinot noir, for example). Unless perfectly judged though, the wines can take on an astringent unappealing, 'green' flavour.

Chester Osborn and The Money Spiders

Chester Osborn
Chester Osborn

The sorting table is also where any creepy crawlies are removed - that is, if the winemaker can bear to: 'The 2000 vintage of my first roussanne was covered in money spiders,' recalls Chester Osborn from d'Arenberg in McLaren Vale, Australia. 'There's an old wives' tale that says that if you're kind to money spiders it'll bring good luck - and maybe even some money. I decided not to send the little critters to their deaths and didn't make the wine that year. We named the next 2001 vintage The Money Spider, which it's still called. By then, [the spiders] had the good sense to move on to the bush.'

Before Fermentation

Prior to the grapes going into the fermenting vessel, the winemaker might need to think about the following:


Chardonnay grapes ready to be pressed
Chardonnay grapes ready to be pressed

While red wine grapes will be pressed afterwards (with the exception of some 'free run' wines), almost all white wine grapes are pressed before fermentation. This separates the skins and juice, so that the latter can be fermented.

Traditional wine presses are vertical, applying pressure to the grapes from a screw at the top of the device. These are still used by some wineries (particularly in Champagne). Most, however, now use horizontal presses, where the pressure can be controlled more accurately - either through a screw, or by inflating a rubber bag inside the vat.

Sulphur dioxide

The devil himself was of course thrown into a burning lake of sulphur, but for most winemakers SO2 is a necessary rather than a punitive evil. It is an important - many would say vital - preservative that can be used before and after fermentation:

  • Before fermentation, it can be used to kill off the bacteria found on the skins of the grapes.
  • After fermentation, it is added to prevent oxidation and to kill off any remaining bacteria or yeasts in the wine.
  • In a few cases, it is even used during fermentation: it can be added to sweet wines to stop yeasts fermenting, killing them off before they have fed on all the sugars.

Some have decreased usage markedly in order to make a more 'natural' wine, while a few producers make wine without it. Most, however, see it as indispensable and the vast majority of wines will have some sulphur dioxide present.

Good winemakers will only use just the right amount of sulphur and the aim is that it is not tasted in the wine. European legislation restricts the amount that can be added to a wine.

Chaptalisation in cool climates and acidification in hot climates

In some cases, a spoonful of sugar really can help the medicine go down. If the grapes do not possess enough sugar to give a sufficient alcohol level - a problem that can occur particularly in cool climates - the winemaker might consider chaptalisation. This is the process of adding sugar to the must, either before or during fermentation. The process is forbidden in many areas of the world, but where it is permitted, some wines do benefit from it.

The process must be carried out with great care and in just the right amounts. Too little sugar will fail to rectify the problem, while too much can result in an unbalanced and unfriendly wine whose fruit flavours will be out of synch with the elevated alcohol level.

In warmer climates, however, the problem is often that there is too little acidity in the grapes, meaning that the finished wine would taste flabby and over-alcoholic. Acidification is usually achieved by adding tartaric acid before fermentation. Like chaptalisation, it is not allowed in all winegrowing areas, and must be used very carefully.


Once the winemaker has considered any necessary and permitted enrichments and, in the case of white wines, pressed the grapes, fermentation can begin.

Fermentation converts the sugars present in the grapes into alcohol, via the interaction with yeast.

The vat

Oak Vats
Oak Vats

Fermentation vessels can be made from several materials, the most widely used being concrete, stainless steel and oak. Each has its own benefits to different types of wine. Fermenting a wine in oak, for instance, adds a creamy richness to the finished wine (such as a richly flavoured white Burgundy), while stainless steel vats retain the crispness and freshness so appealing in many livelier-tasting wines (eg the vast majority of New Zealand sauvignon blanc).

Starting fermentation

Most grapes will begin to ferment naturally once they are placed into a fermentation vessel and crushed, thanks to the natural or 'wild' yeasts present on the grapes and in the winery. Sometimes cultured yeasts are added, normally in powder form. This gives the winemaker a greater degree of control over the process.

Red wines: punching down and pumping over

Punching down
Punching down

To help the yeasts grow and to add colour and tannin to the wine, the skins of red grapes need to be kept in contact with the juice as much as possible. In some ways, this is comparable to coffee grounds needing to be kept in touch with water to make a finished brew. Two processes commonly used in the winery are very similar to those used in coffee making:

  • 'Punching down' acts like a cafetière: a plunger is applied to the skins at the top of the vat (either by machine or by hand using a pole), pushing it down into the juice below it.
  • 'Pumping over' acts like a percolator, pumping wine from the bottom of the tank back over the skins on the top of the vat.

There are other methods: some wineries use rotary fermenters, fermentation tanks that rotate and keep the juice and skins in regular contact. Carbonic maceration enables fermentation to take place inside the individual berries, and is started not by adding yeasts and crushing, but by storing the grapes in a closed container and replacing the oxygen therein with carbon dioxide. This method is often used in Beaujolais due to its ability to create soft and fruity wines.

Stopping fermentation

A stopped fermentation is one carried out by the winemaker's volition, once the wine is felt to have achieved the correct balance of alcohol and sweetness. This can be done by filtering out the yeasts or adding sulphur dioxide.

A 'stuck' fermentation on the other hand is an unhappy accident, which can occur if the heat produced during the process is not controlled properly or if there are insufficient yeasts or nutrients.

Malolactic fermentation

Red wines, and some white wines, will then undergo a second fermentation, in which lactic bacteria convert the malic acids (ie that found in apples) into the softer lactic acid (ie that found in milk). This is done by raising the temperature of the vat before any sulphur dioxide is added. This 'malolactic' fermentation, or 'malo' for short, results in a more softly textured wine with less acidity and more buttery and nutty flavours.

In very hot years like 2009 there is little malic acid in the grapes, whereas a cooler year like 2010 will have much more. In the cooler years the wine is transformed by [malolactic fermentation] and many ugly ducklings have become elegant swans. However, there is a Catch Twenty Two here. The higher acid the vintage, and thus the more beneficial to the wine for the malo to occur, the more difficult it is to start the process.
Toby Morrhall, Society buyer

Maturation: 'Wine Into Wood'

The winemaker may then decide to age the wine in oak before bottling it. Most of the world's fine wines undergo some sort of oak ageing (though there are some notable exceptions such as riesling). Broadly, this can have three beneficial effects:

  • Flavours: new oak barrels can add vanilla, butter or nutty flavours to the wine: for instance, the cedary flavour of top Bordeaux or the creamy, hazelnutty qualities of a fine white Burgundy.
  • Oxygen: the presence of oxygen can in some cases be necessary to soften the tannins (thus adding texture to the wine) and imbue the wine with more complex flavours.
  • Structure: sometimes the influence is more subtle, the wood merely providing tannins that give the wine greater stability and propensity for bottle age.

French oak vs American oak: spicing things up

When cooking and seasoning food, different spices can bring out different flavours in the dish. So it is with wine and the choice of which type of oak to use for maturation.

French oak can impart great elegance, like a complex mixture of spices. American oak is more like chilli: if you get it right, it can be the perfect complement, but get it wrong and it can dominate the wine's fruit flavours.
Pierre Mansour, Head of Buying

The two main types of oak used in winemaking have a number of marked differences, including, but not limited to, the following:

French oak

  • Subtler flavours, such as cedar and spice, that are less obviously 'oaky'. Wines aged in French oak are more likely to elicit adjectives such as 'elegant' and 'refined.'
  • Imparts more tannins, which tend to be silkier and often more complementary to the fruit.
  • More expensive: the tighter grain demands that the wood must be split, meaning that only 25% or so of the tree can be utilised.

American oak

  • More intensely flavoured, giving sweeter and more vanilla-like qualities to the wine. Wines aged in American oak are more likely to be described as 'opulent' or 'hedonistic' (or, indeed, 'oaky'!).
  • Imparts fewer tannins. The emphasis is more on flavour.
  • Less expensive: the tree can be serrated meaning that it is much more economical than French oak.

Age and size of vessel

The type of oak used is only part of the story.

  • The age of the vessel can have a marked influence on how the finished wine will taste. As barrels get older, the levels of flavour and tannins they impart diminish.
  • The size of the vessel also influences flavour and tannin, as the ratio of wood surface to wine will differ. A small barrique will have a far more pronounced effect on the wine than a large vat.

As with the type of wood, the winemaker has to decide what will work best for their wine.

Muga Barrels
Muga Barrels

There are also a number of less expensive shortcuts used by some winemakers to impart oak flavours and tannins without investing in vessels - including oak staves, oak chips or even oak essence. However, compared to barrel ageing these are somewhat crude techniques and this is often reflected in the taste of the finished wine!

Before Bottling: The Final Touches

A few more optional treatments remain for the winemaker to consider before the finished wine is bottled. These can be used to prevent spoilage or to ensure the wine reaches the consumer clean and bright in the glass. While the latter is aesthetically pleasing, and seen by some winemakers as essential, there is a danger that the processes that enable it can strip the wine of some of its flavour, complexity and character.

This is why some winemakers choose to bottle their wines unfined and/or unfiltered. While the wines can be very characterful, they will often appear 'hazy' in the glass. Some may well form a harmless sediment.


Many wines are filtered (of which more later) to make sure that they reach the table clear and bright, without cloudiness or sediment.

However, certain particles (tiny flecks of grape matter, for instance) are so small that they can still 'slip through the net'. These can be taken out of the wine before filtration via fining.

Separating egg whites at Bodegas Muga
Separating egg whites at Bodegas Muga

Fining involves stimulating these tiny molecules to coagulate together into lumps, which will either sink to the bottom of the wine and be drawn (or 'racked') off, or which can be removed easily by filtration afterwards.

The process can soften or remove tannin, which in some cases can improve the overall quality of the wine. Several agents can be used. The most popular include egg whites (albumen), bentonite (diatomaceous earth) and isinglass (a substance obtained from the dried bladders of fish).

Separating egg whites from their yolks for fining is often one of the more laborious and unsung processes. Bodegas Muga in Rioja, use a particularly special, if slightly eccentric, device:

You need 3 egg whites per 100 litres of wine to achieve crystal clear results, so you can imagine how busy the egg separator is kept in the run up to bottling. For those curious to know what happens to the yolks, they are sold off and used for baking the tasty local cakes sold in the town!
Tim Sykes, Society buyer


As well as grape matter, another obstacle in the way of a star-bright glass of wine can be tartrate crystals, which can occur in white wines. Tartrates are harmless, but do resemble small shards of glass and understandably can be a cause for concern with consumers! These can be removed by chilling the wine in bulk, precipitating the crystals before they have the chance to appear in the bottle, and removing them.

Preventing spoilage

A more serious problem can be the presence of yeasts and other bacteria that can spoil the wine by bringing on a secondary fermentation in bottle, rendering the wine deeply unstable and even more deeply unpleasant. These micro-organisms can be killed by adding sulphur dioxide, or in some extreme cases, exposing the wine to a rapid blast of heat, such as by pasteurisation.


If the winemaker wishes, the wine can then be filtered. Filters are not selective, so as a general rule, the gentler the process, the better chance the wine has of not losing any particles that will affect its flavours or its sense of character.

  • Surface filters are generally less expensive, and pass the wine through a membrane. The waste is left on the surface of the membrane, hence the name.
  • Depth filters remove particles and solids by passing them through a bed of, for instance, porous Kieselguhr clay or plastic plates interspersed with filter pads. The waste is left within the substance through which it passes, making the process often more costly.


Bottling at Chapel Down
Bottling at Chapel Down

The wine is now finished and so it's off to the bottling line. Many cellars have their own bottling lines, while others make use of bottling equipment on a hiring basis. Though the wine is done and dusted at this point, bottling is a crucial step and things can still go very wrong if the process is not done correctly.

The key is to ensure as hygienic and sterile an environment as possible to avoid spoilage: the bottles and equipment should be completely clean. Temperature is also important. While some cheaper wines are 'hot-bottled' (a crude form of pasteurisation carried out at the last), the majority rely on a cool temperature to avoid any nasty microbiological surprises.

Closures: corks, screwcaps and points in between

The choice of closure is important for a number of reasons and is an area of both continual innovation and, therefore, continual debate.

Natural corks, synthetic closures and indeed screwcaps all have different categories themselves, making the decision even more complicated. The broader benefits and potential disadvantages of each of these types of closure are as follows:

Natural cork

Natural corks
Natural corks
  • Benefits: The principal benefit is in ageing wines: its slight porosity enables tiny amounts of air into the bottle to help mature the wine. It is a tried and true, but - as we see below - not always trusted closure.
  • Disadvantages: 'Corkiness' or 'corked' wine affects a small number of bottles under cork: a substance called TCA (trichloroanisole) can contaminate the wine causing it to taste musty and unpleasant.

In addition, natural disparities in the physical makeup of different pieces of cork can sometimes result in bottle variation (where one bottle will have received more oxygen than another, meaning that the wine inside will taste different).

Synthetic closures

  • Benefits: There is a multitude of synthetic closures currently available. They range from plastic corks and glass stoppers to wrap-around pieces of plastic holding a lining material in the neck of the bottle. Some closures are also made using treated cork combined with synthetic materials, such as Diam 'technical corks', under which The Society is bottling an increasing number of wines. All of these are designed to ensure greater consistency without tainting the wine.
  • Disadvantages: As many of these closures are very new to the market, their suitability for ageing wines is uncertain. Some have proved difficult to extract, and some have raised environmental concerns, particularly those involving plastic.
Diam have solved two of the greatest problems of the otherwise excellent natural cork: firstly, a fault commonly called 'corkiness', a musty-smelling taint caused when a cork infected with a substance called trichloroanisole (TCA) communicates this to wine, and secondly, the natural variation between different corks in porosity to air, which can lead to extreme variation in the oxidation of wine.
Toby Morrhall, Society buyer


  • Benefits: The screwcap itself is not, strictly speaking, the closure: it is a means to hold a sealing liner in the bottle neck, of which there are two types: a metal version, which allows hardly any oxygen to enter the bottle, and a more porous version called Saranex.
    Screwcaps are excellent at retaining the freshness of a wine (which is particularly well suited to, for instance, young white wines) without needing as much sulphur dioxide, and without the risk of cork taint. They are also comparatively economical. Screwcaps are very popular, in particular in New Zealand and Australia.
  • Disadvantages: Increasingly, screwcaps are being used in tests of aged wines, with many performing favourably vs cork, but their suitability for very long-term ageing is still unknown. The metal version of the sealing liner allows for very little oxygen to enter a wine, which can be both an advantage and disadvantage, depending on the type of wine. Indeed, the main disadvantage of screwcaps is occasional reductive taint: the absence of oxygen can result in unappealing, rubbery smell. Screwcaps have also encountered resistance in some markets due to associations with cheapness, though thankfully these perceptions are waning.

Bottle Age and When To Drink

Rioja ageing in CVNE's cellars
Rioja ageing in CVNE's cellars

With the wine bottled, all that is left is to decide when to release the wine for sale.

In the vast majority of cases, the answer is 'immediately'. As a number of fine wines benefit from bottle age, however, some producers keep their wines in their cellars for a time before releasing it to the market, ensuring the consumer gets it at a point when it is à point (that is to say, ready to drink)!

The wine will need to be ageworthy and the producer will need to have resources to perform this laudable but expensive task. This practice is particularly commonplace in Rioja, where legal regulations demand that some wines be aged in this way: wines bearing the region's top classification, gran reserva, must spend at least three years in bottle before release.

The subject of when to drink an ageworthy wine is often debated and, in the end, it depends on one's personal taste. The Society offers drink dates for all of the wines we sell, and are always on hand for advice on when to broach a special bottle. You may also find our article on Storing Wine useful.

Above all, the most important thing - what this complicated and often arduous process is all in aid of - is that the resultant wine is enjoyed.

Martin Brown

The Society's Managing Editor

Martin Brown

Martin joined our team in 2011 having worked as a professional scribe in various capacities. He is responsible for much of our online and printed communications and is a regular contributor to our Discovery pages.

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