How is Wine MadeWine is an alcoholic beverage made by fermenting juice. All wine is made this way. There are always exceptions, and you can indeed make wine out of other fruit, out of dandelions and even out of the sugars found in elderflower petals. However, we will focus on the alcoholic beverage made of fermented grape juice.
Of course, the simple description of fermented grape juice doesn’t begin to describe the infinite variety of wines available. Wine can be white, light, crisp, fresh and refreshing. It can also be ruby, rich, spicy, robust and hot on the palate. Wine is made in many countries throughout the world. Different combinations of grape type, soil, climate and winemaking practices provide almost endless possibilities for variety. Add to this the seasonal changes in regional weather conditions, ongoing advances in winemaking technology and the skill of the particular winemaker, and wine becomes an ever-changing subject of study. Mind you, there is no need to feel overwhelmed by this – no individual ever really masters it all nor is there any need to. All that is needed is a solid understanding of the basics and you carry on an informed discussion about the world’s great wines. Interested in making your own wine with a little help? Get a head start with our winemaking kits.
Harvesting Wine - Making Wine From Grapes
The grapes themselves are the most important aspect of winemaking. Without good grapes, you cannot make good wine. Over the centuries that wine has been made, certain varieties make the finest wines and accordingly these have been planted in many wine-producing areas. Among them are four particular types: Chardonnay, Cabernet Sauvignon, Riesling and Pinot Noir. Although these are only a small fraction of the many existing grapes varieties, they account for many of the great wines produced throughout the world.
Along with good grapes, you need good timing. As harvest time approaches, the tension in the vineyards becomes almost palpable. Grape growers constantly check the grapes and try to pick them at the peak of ripeness. They look for a balance between sugar and acid. As the grapes ripen, sugar increases while acids decrease. The trick is to harvest when both of these elements are in harmony. Too much sugar and the wine will be flat and flabby. Too much acid and the wine will be sharp and thin. Timing is critical.
More important are the conditions that lead up to this. An ideal vintage would be one that was warm, dry and sunny throughout both the growing and ripening seasons. Ideal vintages are rare. Late frost can appear when you don’t want it, and damage the newly formed buds. Rain has this nasty habit of showing up when it is least wanted and swelling the fruit. Fog can cling to the grape skins and attract unwanted bacteria that lead to rot.
The winemaker hopes that these things don’t happen- the best climate conditions produce the best fruit. Ultimately the winemaker picks when the grapes are ripe and does the best he/she can with what there is to work with.
Once the word is given for the harvest to begin, there is a flurry of activity in the vineyard. The grapes are picked by hand or by mechanical harvest. When they are picked by a machine, the grape skins are usually broken and some of the juice is exposed to air. At this point, the preservative sulphur dioxide may be added to prevent premature fermentation and browning. Premature fermentation can begin at any time.
Pick up any grape, and you will observe a white film on the outside of the skin that looks like dust. This is actually a waxy substance which will have already trapped wild yeast and bacteria that have been floating around in the air. Even limited exposure of the juice to this yeast could start the fermentation process before the winemaker ever wanted it to begin. Sulphur dioxide stops this and will also control the browning or oxidation that could also begin.
When grapes arrive at the winery, they are put into a machine called a crusher/destemmer which removes the stems and crushes the berries. In most wines, the stems must be removed as they may add a bitter flavour to the wine. From the crusher/destemmer, the grapes are moved quickly into the press. In the press, the juice is separated from the pips, skins and stems, and this becomes the base for making wine.
If a grape is cut in half you will notice the juice and the pulp of most grapes is white. Only the skin has any colour. To make red wines, the skins of the red grapes are left with the juice, releasing their colour during fermentation. In most white wines, the skins are removed completely- no skins, no colour.
To produce a rose wine with just a trace of pink colour, the skins of red are left in the fermentation vat for a very short time and then removed.
How a wine is aged can greatly affect the flavour of the wine. It will depend largely on the intentions of the winemaker. Some wines will be bottled immediately, and consumed young. Some wines will age in stainless steel or in glass-lined tanks but the result is not the same as if they were aged in barrels. However, barrel aging is very expensive.
Many of the aging reactions that take place need the presence of oxygen. In most cellars, they are topped twice weekly in winter and three times in summer to compensate for evaporation. The air space between the top of the wine and the top of the barrel is called ullage. Ullage is also the proper term for the air space between the cork and the wine itself in a bottle of wine.
During the early stages of aging, the wine rests undisturbed. Any particles left over from the fermentation process slowly settles to the bottom of the container, be it oak or stainless steel. Racking is generally done four times during the first year. Depending on the quality of the wine, it might be aged longer and racked accordingly.
Wine Fermentation - And Why It's Important
Alcoholic fermentation is the conversion of sugar in a liquid into ethyl alcohol and carbon dioxide through the action of yeast. In other words, the yeast feeds on the sugar in the liquid, thereby producing alcohol and carbon dioxide. If you look at a fermenting liquid, you will see it bubbles and froths as carbon dioxide gas escapes into the air. This bubbling activity can be very vigorous, resulting in an almost boiling appearance.
Although the wild yeasts on the skins of the grapes will start the fermentation ( in fact, it’s rather hard to stop them), most winemakers use cultured yeasts in order to get the results they want as cultured yeasts creates heat. In warm climates such as California’s, the winemaker must cool the fermentation tanks in order to prevent the wine from tasting coked. When fermentation is finished, the wine is drained off and either held in stainless steel tanks to rest and clear or put into oak barrels to age and mature.
Fining is the process that ensures that the wine will be perfectly clear and free of suspended particles. Gelatin or egg white is added to the cask; these substances congeal, attracting to themselves any minute particles which may been floating in the wine. The whole mass then settles to the bottom of the cask. In white wines, organic fining substances such as Spanish clay, or bentonite, are also used to clear the wine. None of the substances will in any way add to or change the flavour. When the sediment has settled, the wine is racked and bottled, or transferred to barrels.
Filtering is done through filter pads, diatomaceous earth or even ceramic micropore filters. Even this process must be done carefully because while it will enhance the clarity, it can also strip some of the flavouring elements out of the wine.
Racking is the draining or pumping of the wine from one barrel into another clean and sterile barrel, leaving the less or sediment behind. In some areas, racking has become obsolete.
So How Is Red Wine Made?
Red grapes are harvested and crushed, and the combination of broken skins, juice, pulp, seeds and sometimes stems are left to ferment together to extract colour from the skins and tannins from the seeds and stems.
The amount of fermentation on the skins varies from a few days to a few weeks, depending on the type of wine desired. The lighter wines are drained off earlier than the heavier ones. With longer fermentation on the skins, some tannin, other acids and flavouring substances are extracted from the skins and the seeds. These substances play a vital role in the maturation of richer red wines.
Another method of extracting colour from the grape skins is by hot pressing. In this process, the grapes are crushed and the resulting must is heated to between 60 and 80 Centigrade. It is held at this temperature for up to one hour or until the desired degree of colour extraction is reached. The must is then pressed and the deeply coloured juice is fermented. This process is useful when quick production is necessary, as it takes a fraction of the time.
The classic method for rose is start the process as if you were making a red wine, but remove the skins from the juice after a short while. This period can vary from 8 to 48 hours depending on the temperature and the amount of colour the winemaker has in mind. The maturation of a rose will usually last a little longer than that of a white. A good rose will have the depth of flavour of a light red but the crisp, clean finish of a good dry white. There was a trend in the 1980’s especially in California, to call paler version of this a blush, as they are more faint in colour than the traditional rose. Some of these were even made by blending red and white wines together. This trend is now fading and traditional dry, crisp, refreshing roses are coming back into their own. Looking to make your own red wine at home? Get help with our red wine kits.
And How is White Wine Made?
Each type of wine, be it red, white or rose, requires specific treatment or handling. With white wines, the grapes are crushed and pressed immediately upon arrival at the winery and the juice is separated from the skins, seeds and pulp. The juice is then transferred to tanks or casks, ready for fermentation. White wine may be fermented in large vats or small barrels, but better quality fermentation can be achieved in large temperature controlled stainless steel vats. The secret of making a fine white wine lies in a slow, controlled fermentation at a low temperature. Vats are only partially filled since the must, or fermenting juice, expands and foams, and grape particles will rise to the top. When the first bubbling fermentation has ended, the leftover yeast particles called the lees begin to settle and a light racking is done. The most common problem to occur in white wines is the formation of a white protein cloud, a situation, which is best, prevented by fining with bentonite.
White wine is kept at lower temperatures than red wine. This encourages tartrates and similar substances to drop out in the tank and be left behind when the wine is bottled. Due to the relative lack of tannins, white wines do not take as long to mature as red wines- usually six months to a year. The lighter fruit flavours of white wines tend to be overwhelmed by wood flavour. In order to prevent this, many winemakers store their white strickly in stainless steel or glass lined vats, which cannot add any flavour to the wine. Some white wines made from Chardonnay, Sauvignon Blanc, Semillon or Marsanne grapes with the right amount of oak aging can take on a depth of character and flavour that they might never otherwise achieve. But, the winemaker must be particularly careful to achieve fruit and oak.
It is fresh scent and taste of the grape that is most appreciated in white wine. Most lightly bodied white wines are bottled five to eight months after the harvest. Some fuller bodied whites may be kept in the tank or the cask a bit longer. Again, the vintner can make a white wine that is intended for long aging but most white wines are vented for immediate drinking. Looking to make your own white wine? Get help with our white wine kits.