The key to crafting a lusciously sweet wine lies in preserving a portion of the grape's natural sugars even after the fermentation process. When yeast is introduced to crushed grape juice during fermentation, a magical transformation occurs, where the grape sugars are converted into alcohol and carbon dioxide. Typically, this results in a dry wine, devoid of sweetness. However, to attain that delightful, natural sweetness in wine, vintners employ various techniques to safeguard a certain amount of grape sugar from the voracious appetite of yeast.
Introducing Sweetness Prior to Fermentation: Some of the most exquisite sweet wines are born from a deliberate act of enhancing the sugar content within the grapes right from the inception of the winemaking journey. This strategic move ensures that a portion of the grape's inherent sugars remains untouched by the fermentation process, escaping conversion into alcohol and carbon dioxide. The aim is to have grapes so rich in sugar that the yeast's vitality diminishes before it can fully metabolize all the sugars in the juice (naturally, yeast ceases activity around 15% alcohol by volume).
Grapes Dehydrated to Perfection: One method of elevating sugar concentration within the grapes involves the gentle removal of water from the fruit. Grapes left on the vine for an extended period can gradually desiccate, makingthem prime candidates for crafting sweet wine when harvested later in the season. Alternatively, winemakers sometimes lay freshly plucked, healthy grapes in well-ventilated, arid conditions to stimulate evaporation and gently desiccate the grapes before embarking on the fermentation process. An illustrious example of this technique is the world-renowned PX Sherry, which is crafted using sun-dried Pedro Ximénez grapes
Harvesting the Elegance of Noble Rot: Yet another pivotal technique for enhancing sugar concentration involves harnessing the captivating effects of mold, affectionately known as 'noble rot' or 'botrytis,' which selectively targets healthy grapes still clinging to the vine. Noble rot, with its enigmatic presence, weakens the grape skins, thereby accelerating the process of moisture evaporation from the grape flesh and causing the fruit to gracefully shrink. This unique fungal influence imparts its own distinct flavor profile to the wine. Successful growth of this mold relies on very specific environmental conditions, and it is therefore predominantly utilized in the production of premium sweet wines, such as Sauternes and Beerenauslese. Since the mold does not affect all grape clusters uniformly, crafting the finest wines in this manner entails the meticulous hand-picking of grapes from the vine.
Harvesting the Brilliance of Frozen Grapes: The ultimate technique for intensifying the sugar content within the grapes involves an extended period of patience, as the fruit remains on the vine well into the winter season. During this time, in the most extreme weather conditions, the water within the grapes undergoes a dramatic transformation—it freezes. When these frozen grapes are carefully harvested and subsequently crushed, a remarkable process unfolds. Ice crystals, naturally formed during freezing, can be skillfully separated, leaving behind a sumptuously concentrated, sugary grape syrup of unparalleled richness. What distinguishes this method is that the juice originates from perfectly healthy grapes, untouched by rot, imparting a pristine and notably pronounced flavor profile. Wines crafted using this approach bear the moniker "Eiswein" in Germany and Austria, or "Icewine" in Canada, capturing the essence of this extraordinary winemaking tradition.
- Philip Stephenson-Oliver