Winemaking
The 20th century saw many advances in winemaking technology and practices—particularly the introduction of temperature-controlled fermentation and controlled inducing of malolactic fermentation. One winemaking issue that has seen some controversy in the region is the use of oak. Historically Chablis was aged in old wooden feuillette barrels that were essentially neutral-meaning that they did not impart the characteristic oak flavors (vanilla, cinnamon, toast, coconut, etc.) that are today associated with ageing a wine in barrels. Hygiene was difficult to control with these older barrels, and they were prone to developing faults in the wine, including discoloration. Gradually the use of these old neutral barrels fell out of favor in lieu of stainless steel fermentation tanks which also added the benefit of controlling temperatures. The use of oak became controversial in the Chablis when some winemakers in the late 20th century "rediscovered" the use of wood barrels in winemaking and began using newer oak barrels that did impart oak flavoring the wine. So-called "tradionalist" winemakers dismissed the usage of oak as counter to the "Chablis style" or terroir while other so-called "modernist" winemakers embrace its use though not to the length that would characterize a "New World" Chardonnay.
The amount of "char" in oak barrels used in Chablis is often very light, which limits the amount of "toastiness" that is perceived in the wine. The advocates of oak in Chablis point to the positive benefits of allowing limited oxygenation with the wine through the permeable oak barrels. This can have the effect of softening the wine and make the generally austere and acidic Chablis more approachable at a younger age. The winemakers who prefer not to use oak, ferment and mature their wines in stainless steel or concrete tanks. The winemakers who do use oak tend to favor more neutral oak that doesn't impart the vanilla characteristic associated with American oak. These producers may only ferment the wine in oak and then mature in steel or concrete, or do the reverse and mature in oak. Rarely will a producer use oak for both fermentation and maturation. Grand Cru and Premier Cru wines are the candidates most likely to see oak due to the belief that they have necessary structure and enough extract to keep from being overwhelmed by oak influence. While there are style differences among producers, rarely is basic AOC Chablis or Petit Chablis oaked.
While chaptalization was widely practiced for most of the 20th century, there has been a trend of riper vintages in recent years, producing grapes with higher sugar levels that have diminished the need to chaptalize.
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