Originating in south-west France, but grown in almost every region where the climate is warm enough to ripen the grapes, Cabernet Sauvignon is a thick-skinned, low-yielding, late-ripening variety producing deep coloured, tannic wines with a strong varietal flavour used in the production of rosé, sparkling red medium to full-bodied styles with aging potential or blended with other varieties for added complexity. Tannins and affinity with oak allow the wines to improve in bottle, developing a range of vanilla, cedar, sandalwood, tobacco, coffee, musk and spicy notes. It is equally capable of producing affordable, everyday reds as it is of producing wines with finesse and class. For most of the 20th century, it was the world's most widely planted premium red grape until surpassed by Merlot in the 1990s.
First identified as Vidure due to hard woody stalks DNA fingerprinting revealed a 17th century chance cross-pollination between Cabernet Franc and Sauvignon Blanc produced a single hybrid vine from which all Cabernet Sauvignon vines are descended, confirming the combination of names and the fact Cabernet Sauvignon displays both the black currant and pencil box aromas of Cabernet Franc and the grassiness of Sauvignon Blanc.
Cabernet Sauvignon produces bunches of small, thick-skinned, blue-black berries with a high ratio of solids to juice. The vines are hardy and resistant to most grape diseases (with powdery mildew the most noted exception) and frost. It is one of the last varieties to bud and ripen (a week or two after Merlot and Cabernet Franc) and the climate affects how early the grapes will be harvested.
When young, the wines tend towards flavours of black cherries and plum with aromas of black currants. The wines may also show hints of eucalyptus, mint and tobacco. As the wines age they develop aromas associated with cedar, cigar boxes and pencil shavings. New World examples tend to have more pronounced fruity notes while Old World wines are more austere with heightened earthy notes.
In cooler climates, vines produce foliage to capture sunlight for photosynthesis, rather than ripening grapes, so canopy management and pruning are important considerations for growers. Unripe Cabernet from regions that are too cool can be herbaceous with capsicum and grassy undertones, but as it ripens it tends towards blackcurrant and cassis. In regions where the grape is exposed to excess warmth and over-ripening, the wine develops flavours of cooked or stewed blackcurrants.
Harvest yields can also influence the quality and flavours of Cabernet Sauvignon. Excessive yields result in less concentrated wine with green or herbaceous flavours. To reduce yields, producers can plant the vines on less vigorous rootstock and practice green harvesting with aggressive pruning of grape clusters soon after veraison.
The most noted flavours tied to viticulture and climate are herbaceous or green bell pepper flavour from pyrazines in under-ripe grapes. These compounds are present in all Cabernet Sauvignon grapes but are sunlight gradually destroys them as the grapes ripen. In cooler climates it is difficult to get Cabernet Sauvignon to ripen fully and while the green bell pepper flavour is not considered a fault it may not be desirable either.
Mint flavours are associated with regions warm enough to have low pyrazine levels but are still relatively cool, such as Coonawarra. Soil could also be a contributor since the flavour appears in wines from the Pauillac but not from similar climate of Margaux. Eucalyptus flavours tend to appear in regions that are habitats for the eucalyptus tree, but there has been no evidence to prove a link between nearby eucalyptus trees and the presence of that flavour in the wine.
High proportions of phenols and tannins influence the structure and flavour of the wine— especially if the must undergoes lengthy maceration before fermentation with more tannins extracted from the skin. In Bordeaux, maceration traditionally took three weeks, producing tannic wines needing years of aging.
If winemakers choose to maximise colour and flavour, tannin levels can be softened by aging in oak, which exposes the wine to gradual oxidation, mellowing harsh grape tannins, introducing softer wood tannins and introducing vanilla and spice notes which complement natural grape flavours of black currant and tobacco. American oak, particularly from new barrels, imparts stronger flavours than French oak. Winemakers often use a variety of barrels from different locations and of different ages and blend the wine as if they are blending different grape varieties.
Winemakers can also use large barrels with a smaller wood-to-wine ratio, resulting in less pronounced oak flavours. Another method involves tea bagging with oak chips or adding oak planks to the wines while fermenting or aging in stainless steel tanks. While these methods are cheaper than using barrels, they create pronounced flavours, which tend not to mellow or integrate with the rest of the wine's components; nor do they provide the gradual oxidation of barrel aging.
Fining agents including gelatin and egg whites bond with some of the tannins which are removed from the wine during filtration. Micro-oxygenation mimics some of the effects of barrel aging, with exposure to oxygen aiding the polymerisation of tannins into larger molecules, which are perceived as softer on the palate.
After maceration, the must can be fermented at temperatures up to 30 °C, with deeper colours and flavour components extracted at higher temperatures while more fruit flavours are maintained at lower temperature.