Sweetness of wine

The subjective sweetness of a wine is determined by the interaction of several factors, including the amount of sugar in the wine, but also the relative levels of alcohol, acids, and tannins. Sugars and alcohol enhance a wine's sweetness, while acids cause sourness and bitter tannins cause bitterness. These principles are outlined in the 1987 work by Émile Peynaud, The Taste of Wine.^[1]

According to the International Organization of Vine and Wine (OIV), wines can be classified based in their sugar content. A wine is considered dry when it contains no more than 4g/L of glucose plus fructose or when its acidic strength is at least 2g/L relative to glucose plus fructose. Medium dry wines have a sugar content higher than that of dry wines. Mellow or semi-sweet wines contain more sugar than the medium dry wines but no more than 45g/L. Sweet wines contain at least 45g/L of glucose plus fructose.^[2]

Vintage: The Story of Wine, a book authored by British wine writer Hugh Johnson, presents several methods that have been used throughout history to sweeten wine. The most common way was to harvest the grapes as late as possible.^[3] This method was advocated by Virgil and Martial in Roman times. In contrast, the ancient Greeks would harvest the grapes early, to preserve some of their acidity, and then leave them in the sun for a few days to allow them to shrivel and concentrate the sugar. In Crete, a similar effect was achieved by twisting the stalks of the grape to deprive them of sap and letting them dry on the vine—a method that produced passum and the modern Italian equivalent, passito.^[3]

Stopping the fermentation also enhanced a wine's potential sweetness. In ancient times, this was achieved by submerging the amphorae in cold water until winter.^[3]

El vino también puede endulzarse añadiéndole azúcar de alguna forma, una vez finalizada la fermentación, como en el método alemán del Süssreserve . En la época romana, esto se hacía para preparar el mulsum , un vino recién endulzado con miel y aromatizado con especias, que se consumía como aperitivo, y también para elaborar el conditum , que tenía ingredientes similares pero se maduraba y almacenaba antes de beberlo. Desde la época romana hasta hace relativamente poco , también era común endulzar el vino con azúcar de plomo , una sustancia tóxica que aumenta el dulzor aparente de los vinos y otras bebidas. Esta práctica continuó hasta bien entrado el siglo XIX, aunque el uso de plomo se limitó principalmente a vinos muy baratos después de que se demostrara su naturaleza nociva en el siglo XVII. ^{[ 4 ]}

Entre los componentes que influyen en el dulzor de un vino se encuentra el azúcar residual. Este se suele medir en gramos de azúcar por litro de vino, a menudo abreviado como g/L. El azúcar residual se refiere normalmente al azúcar que queda después de que la fermentación se detiene, o se interrumpe, pero también puede ser el resultado de la adición de mosto sin fermentar (una técnica practicada en Alemania y conocida como Süssreserve ) o azúcar de mesa común.

Incluso entre los vinos más secos, es raro encontrar vinos con un nivel inferior a 1 g/L, debido a la no fermentabilidad de ciertos tipos de azúcares, como la pentosa . Por el contrario, cualquier vino con más de 45 g/L se consideraría dulce, aunque muchos de los grandes vinos dulces tienen niveles mucho más altos. Por ejemplo, las grandes añadas de Château d'Yquem contienen entre 100 y 150 g/L de azúcar residual. La forma más dulce del Tokaji , el Eszencia, contiene más de 450 g/L, con añadas excepcionales que registran 900 g/L. Estos vinos son equilibrados, evitando que resulten empalagosos, gracias a un uso cuidadosamente desarrollado de la acidez . Esto significa que los mejores vinos dulces se elaboran con variedades de uva que mantienen su acidez incluso en niveles de madurez muy altos , como Riesling y Chenin blanc .

How sweet a wine will taste is also controlled by factors such as the acidity and alcohol levels, the amount of tannin present, and whether the wine is sparkling or not. A sweet wine such as a Vouvray can actually taste dry due to the high level of acidity. A dry wine can taste sweet if the alcohol level is elevated.^{[1]:198–199} Medium and sweet wines have a perception among many consumers of being of lower quality than dry wines. However, many of the world's great wines, such as those from Sauternes (including Barsac) or Tokaj, have a high level of residual sugar, which is carefully balanced with additional acidity to produce a harmonious result.

Süssreserve (German: Süßreserve; lit.'sweet reserve') is a wine term referring to a portion of selected unfermented grape must, free of microorganisms, to be added to wine as a sweetening component. This technique was developed in Germany and is used with German-style wines such as semi-sweet Riesling or Müller-Thurgau.^[5] The technique not only raises the sugar level of the wine, but also lowers the amount of alcohol. Under German law, no more than fifteen percent of the final wine's volume may be the reserved juice.^[6] This practice is allowed also for Prädikatswein, the highest level in the German wine classification. It is often used for semi-sweet Kabinett and Spätlese, but more rarely for Auslese and upward.

The use of Süssreserve results in a different composition of sugars in the wine in comparison to residual sugar from arrested fermentation. Grape must contains mainly the sugars glucose and fructose. When wine ferments, glucose is fermented at a faster rate than fructose. Thus, arresting fermentation after a significant portion of the sugars have fermented results in a wine where the residual sugar consists mainly of fructose, while the use of Süssreserve will result in a wine where the sweetness comes from a mixture of glucose and fructose.

• Efectos del vino en la salud
• Maridaje de vinos y comida