right|thumb|Barolo, like most nebbiolo-based wines, is known for its light colour and lack of [[opacity (optics)|opacity.]]
Barolo ( , , ; ) is a red (DOCG) wine produced in the northern Italian region of Piedmont. It is made from the nebbiolo grape and is often described as one of Italy's greatest wines.
The zone of production extends into the communes of Barolo, Castiglione Falletto, Serralunga d'Alba and parts of the communes of Cherasco, Diano d'Alba, Grinzane Cavour, La Morra, Monforte d'Alba, Novello, Roddi, and Verduno, all in the province of Cuneo, south-west of Alba. Although production codes have always stipulated that vineyards must be located on hillsides, the most recent revision of the production code released in 2010 goes further, categorically excluding valley floors, humid and flat areas, areas without sufficient sunlight, and areas with full-on northern exposures.
Barolo is often described as having the aromas of tar and roses, and the wines are noted for their ability to age and usually take on a rust red tinge as they mature. Barolo must be aged for at least 36 months after the harvest before release, of which at least 18 months must be in wood.
In the past, Barolo wines tended to be rich in tannin. It can take more than 10 years for the wine to soften and become ready for drinking. Fermenting wine sits on the grape skins for at least three weeks, extracting huge amounts of tannins, and is then aged in large, wooden casks for years. In order to appeal to more modern international tastes, those that prefer fruitier, earlier-drinking wine styles, several producers began to cut fermentation times to a maximum of ten days and age the wine in new French oak barriques (small barrels). "Traditionalists" have argued that the wines produced in this way are not recognizable as Barolo and taste more of new oak than of wine. The controversies between traditionalists and modernists have been called the "Barolo wars". This was attributed to the fact that the nebbiolo grape ripens late in October, meaning that temperatures would be steadily dropping by harvest. By November and December, temperatures in the Piedmont region would be cold enough to halt fermentation, leaving a significant amount of residual sugar in the wine. Another popular idea was that in the mid-19th century, Camillo Benso, Conte di Cavour, the mayor of Grinzane Cavour, invited the French enologist Louis Oudart to the Barolo region to improve the winemaking techniques of the local producers. Using techniques focusing on improving the hygiene of the cellar, Oudart was able to ferment the nebbiolo must completely dry, making the first modern Barolo. This new, "dry" red wine soon became a favourite among the nobility of Turin and the ruling House of Savoy, giving rise to the popular description of Barolo as "the wine of kings, the king of wines".
By the mid-20th century, wine production in the Barolo zone was dominated by large negociants who purchased grapes and wines from across the zone and blended them into a house style. In the 1960s, individual proprietors began estate bottling and producing single vineyard wines from their holdings. By the 1980s, a wide range of single-vineyard bottlings was available, which led to a discussion among the region's producers about the prospect of developing a Cru classification for the area's vineyards. The cataloguing of Barolo's vineyards has a long history dating back to the work of Lorenzo Fantini in the late 19th century and Renato Ratti and Luigi Veronelli in the late 20th century, but as of 2009 there is still no official classification within the region. By using modern technology, including specialized tanks that allow the wine to be pumped out from underneath the cap of skins and then pumped over, they found ways to maximize colour extraction and minimize harsh tannins. Prior to this "modernist" movement, nebbiolo was often harvested slightly unripe and at high yields, which left the grapes with harsh green tannins that had not had time to fully polymerize. To maximize colour extraction, producers subjected the wine to extended periods of maceration, taking up to several weeks, and then several years of ageing in large oak casks to soften the wine. Through the long slow process of oxidation, the perception of tannins lessened (such as occurs when decanting wine), but the fruit would also fade and become oxidized. The decline in fruit would no longer be able to balance the remaining harsh tannins, leaving a bitter, astringent wine with withered fruit. To counter this change, some producers would blend in other grape varieties such as Arneis and Barbera to add colour, fruit or softness to the wine.
Located among the Langhe hills, the Barolo zone is a collection of different mesoclimate, soil types, altitudes and expositions that can have a pronounced effect on the development of the nebbiolo grape and the resulting Barolo wine. In Jan 2007 Filippo Bartolotta indicated how a vertical tasting of Barolo, from 1985 to the present "showcased Barolo's longevity, intense aromatics, freshness, silk-and-cashmere tannins and also highlighted the considerable contrast between production zones".
Being dependent on a grape that is slow to ripen, global warming has had a beneficial influence on the Barolo zone. Theoretically, the increased temperatures of summer followed by mild autumns that promote misty fog that keeps the grapes from burning has helped to increase sugar levels and led to riper phenolic compounds such as tannins. To empirically link this to anthropogenic global warming is speculative. More likely, better vineyard management and winemaking techniques have contributed to a string of successful vintages for Barolo in the last 20 years.
The Barolo zone can be broadly divided into two valleys. The Serralunga Valley to the east includes the communes of Castiglione Falletto, Monforte d'Alba and Serralunga d'Alba. Planted with soils higher in sand, limestone, iron, phosphorus and potassium, the wines of Serralunga Valley tend to be austere and powerful and require significant ageing (at least 12–15 years) to develop. The Central Valley to the west includes the communes of Barolo and La Morra with soils higher in clay, manganese and magnesium oxide. This region tends to produce wines with more perfumed aromas and velvety textures. These wines tend to be less tannic and full-bodied than those from the Serralunga Valley and can require less ageing (8 to 10 years). According to DOCG regulations, Barolos are to be composed of 100% nebbiolo. Historically producers would blend other grapes such as Barbera and today there is speculation that modern Barolo producers may be blending in Barbera, Cabernet Sauvignon, Merlot and Syrah but there has been no conclusive proof of this practice. In the 1990s producers in the Barolo zone petitioned that the required nebbiolo content be lowered from 100% to 90% but this petition was eventually defeated. In Piedmont, the wines are often paired with meat dishes, heavy plates of pasta and rich risotti; the tannins bind to the food proteins and come across as softer.