There are generally two distinct styles of sweet wines made in almost all wine producing countries in the world. They fall loosely into two main categories, wines made from ultra-ripe, dried or rotten grapes, and those made by the addition of alcohol (fortified).
It is impossible to pin down exact dates, or even cultures, that by accident or design began making sweet wine. Records do show that the Romans drank a form of sweet wine fermented from very dry grapes – raisins – and the practice of adding grape spirit to fortify still wine began in various monastic outposts throughout Europe. But one thing is certain: over many centuries man has attempted to create sweet wine for the monastery or the court table of kings and queens, and to this day continues to make wines of such eloquence and unctuousness, in spite of the disproportionate work involved and the concomitant prices thereof.
In our own lifetimes wines labelled as “sweet” (remember Spanish Sauterne?) have often been wide of the mark, with still wine, mainly white, having an approximate dose of sugar added, creating bland sugary styles without the necessary balance of acidity to aid refreshment. With residual yeast in the wine, additional sugar would often re-commence fermentation producing gas, which at best, created a “petillant” style, ie fizzy and, at worst, could blow the cork out of the bottle. Adding insult to injury winemakers would then add considerable quantities of sulphur dioxide to kill off, or stun, any further yeast activity. The resultant wines rightly deserved the bad press they received.
Most commercially sweet wines from modern wineries avoid this chemical pendulum swing, resulting in some dessert wines being the finest and often most expensive wines in the world.
Sweet Wine – Noble Rot
By far and away the largest section of sweet wines produced occur because of a small, penetrating fungus generally called “Noble Rot” or Botrytis cinera. Contrary to popular belief Noble Rot can only work its inevitable magic upon grapes that have ripened and are already in a healthy undamaged form on the vine. Weather plays a fundamental part in this process. With the rising of the sun comes the early morning mist in selected vineyards often adjacent to rivers or lakes. These damp conditions encourage the botrytis fungus to spore and propagate on the skin of the grape with microscopic roots penetrating through to the fruit, releasing minute quantities of water to the air. This must be followed, as the sun rises in the sky, with a warm, often hot, burn on the fruit, which then dries out the grape bunches. Visually, the grapes look an ugly rotten mess at this stage, but are clearly poised for greater things to come. Affected grapes are by necessity picked by hand and many metres are walked back and forth through the vines during harvest time to collect the selected botrytised grapes over many days.
In France, Sauternes in southern Bordeaux and the regions of Alsace and the Loire are famed providers of the luscious wines, as are Tokay in Hungary, followed by Germany, Austria and even Italy.
Although botrytis is called Noble Rot by the English, in France it is known as “Purriture Noble”, in Germany, “Edelfäule” and in northern Italy it is called “Muffa”.
If confused by the label of such wines, which are far from self-explanatory by the way, look to Bordeaux for the long-lived Sauternes and the somewhat lesser sweet wines of Monbazillac. In the north of France, along the parts of the Loire Valley, wines are often labelled “Moelleux” alongside some stunning Botrytised Chenins in Savennieres. In the north east the sweet wines of the Alsace are generally labelled “Sélection de Grains Noble”. In Austria, alongside the vast lake near Burgenland, wines are labelled similarly to the German styles as “Beerenauslese” and “Trockenbeerenauslese”. From Hungary comes the traditional half litre bottle of sweet Tokay, with its tell-tale amber colour and overtones of fresh hive honey. Delineation of its sweetness rise in number from three to seven “puttonyos”.
As always with the proverbial “can-do” attitude of the new world, principally Australia and California, winemakers have developed a method to out-smart any naturally lacking elements of their arid micro-climates by spraying harvested grapes with botrytis spores, achieving some similarity to France and Germany in the resulting styles of wine.
Sweet wines – late picked and dried grapes
As with wines subjected to Noble Rot, late picked sweet wines are predominantly made from white grape varieties. These grapes are unusually ripe when picked, often approaching a raisined characteristic to the eye. It is during fermentation that such sweetness comes to the fore, whereby the natural grape sugars inherent in all varieties are not completely turned into alcohol by the additional or natural airborne yeasts. With high sugar levels, yeast struggles to work fully and often give up completely at 8% to 9% alcohol, leaving some sugar starches intact in the final taste. Some of Germany’s greatest sweet wines are evidenced by this simple process.
An additional tool brought into use is when the winemaker feels that refreshing acidity, suitable alcohol levels and the right degree of sweetness have been achieved, judicious introduction of Sulphur Dioxide will halt all further fermentation and therefore any additional chemical change. Sometimes this cessation of activity can be created by freezing or centrifuging. Another method of concentrating the natural sweetness of the chosen grape variety is to simply dry (or raisin) the grape. This can be undertaken in a number of ways, the simplest being to clear the vine canopy of its large, green leaves and flip the bunches on to the top of the vine to dry naturally in the sun. A more controlled system is to bring inside rich, ripe grapes and lay them on aerated racks supported by straw mats to avoid any mould or fungal growth. One famous example of this method are the wines of north east Italy such as “Recioto” or “Passito”. Small pockets of similarly styled wines in the Rhône Valley in France using this racking system are the delightfully sweet rustic wines known as “Vin de Paille”.
Sweet wines – Eiswein
One further method of producing intensely sweet wine with tremendous concentration is by leaving perfectly ripe grapes on the vine, often into the following year beyond harvest, in order to freeze the grapes solid. This clearly restricts such an occurrence to more northerly climes: Germany, Austria and, not surprisingly, Canada fit this category perfectly.
To make ice wine, or “Eiswein”, grapes are picked when frozen like bullets, effectively freezing the water out as crystals, once again concentrating the natural sugars and the all important acidity. Again, in on or two new world wine producing countries, grapes are frozen chemically to try and mirror the winter effects that nature provides.
Fortified wine
Fortified wines are made by the addition of grape spirit prior to the completion of the fermentation process, which has the effect of retaining some of the sugars prior to their conversion into alcohol. Port, Malmsey and Madeira are the classic examples. In certain French regions a similar technique is applied to barely fermented grape juice and effect the general category of “Vin Doux Naturels”. The most commonly drunk in this country is Muscat de Beaumes-de-Venise and Muscat de Rivesaltes. In the Rhône Valley a tawny Rasteau is widely known here as is Banyuls from the south.
Many fortified wines, which, when young, offer a raw, untamed taste, benefit greatly from years stored in barrel and bottle.