I prefer unoaked Chardonnay with my meals, unless I’m having barbequed white meats or fish. But even Chardonnays with “unoaked” on the label can taste as if they have spent some time in oak. Why is that? To find the answer, I recently put the question to several vintners I know and people in the wine industry with whom I deal. Everyone I spoke to agreed that the term "unoaked" whether it appears on the front label or in the "poetic" descriptive material on the back label, allows the vintner quite a bit of leeway, since "unoaked" is an unregulated term.
One vintner explained, "..sometimes a wine is originally meant to be unoaked, but the winemaker finds it to be lacking in acid, richness and overall complexity. In order to counter that flatness he/she might blend back a little of their oaked Chard." This idea was further elaborated on by one of our major California wine distributors, who said, "... I would say that it is very common for California vintners to ferment the wine in tank and then move it to old barrels for 4-6 months to give it texture and some oxygen. Really not “unoaked”, but by California standards it is considered to be. There are almost no Chardonnays, or even Sauvignon Blancs from California that don't see any oak."
As to the difficulty of even deciding whether an "unoaked" label is truthful or not, one vintner posited, “... If a producer makes a Chard that is fermented primary in oak and then puts it through malolactic fermentation in oak again (so that it has a huge oak character), and also makes another Chard which is 90% stainless, …well by comparison the second is unoaked. So while it is possible that the label police could come after the producer, it's not likely."
But if the wine is truly unoaked, how can it taste oaked? A few vintners said that leaving Chardonnay on the skins (or the lees) for an extended period would allow for more phenolics than you might expect from a Chardonnay. One vintner said, "…these phenolics from the skins could form phenolic aldehydes, which are normally contributed to whites through the breakdown of oak lignin. So, that could explain some vanilla or spice aroma."
Another vintner highlighted the need to distinguish the "buttery" aspect of malolactic fermentation from the "vanillin" aspect of barrel aging. "Many tasters will attribute any buttery character to oak, but the buttery aromas are mostly diacetyl -- which is a metabolic by-product of malolactic fermentation. Diacetyl, by the way, is the chemical used to flavor microwave popcorn. Vanillin can be found in oak, and I have noticed that some tasters will confuse vanillin with diacetyl."
What I've learned from this exercise is that I shouldn't put much stock in the term "unoaked" on a wine label other than to regard it to mean "minimally oaked, if at all" – Jay Roelof – www.suburbanwines.com