Where Does The Buttery Flavor in Some Chardonnay Come From?

Find out what microwave popcorn and buttery Chardonnay have in common in this edition of Ask The Expert!

Up next in our Ask The Expert series is a question that most wine lovers have wondered at one point or another – why is it that some Chardonnay has the unmistakable buttery taste and aroma of movie theatre popcorn? For our expert answer we turn to winemaker Anthony Beckman of Balletto Vineyards in the Russian River Valley.

Here’s Anthony’s insightful answer to the question: Where Does The Buttery Flavor in Some Chardonnay Come From?

Love it or hate it, that buttery aroma in Chardonnay is a stylistic decision that any winemaker can easily enhance or greatly diminish.

The aroma stems from one small molecule called diacetyl (C4H6O2, for the super geeks out there.) It is a natural by-product of fermentation, and in the case of wine fermentation, it occurs at high levels during the secondary fermentation when bacteria convert malic acid to lactic acid. The molecule itself is highly potent in terms of aromatic power and a little bit (0.02 mg/L) is enough to be detected in white wine. (Diacetyl is the same exact molecule used in microwave popcorn, margarines and other “buttery” foods.)

It turns out that while these bacteria produce good amounts of diacetyl, they also naturally consume it. So the buttery aroma will be most potent when the wine is at the height of malolactic fermentation and the bacteria are producing more diacetyl than they are consuming. But in the later phases of fermentation, the bacteria are able to convert nearly all the diacetyl, leaving the wine completely void of buttery aromas.

Removing the buttery aroma is as simple as waiting a few extra weeks and allowing the bacteria to naturally convert the diacetyl before disrupting the fermentation. Conversely, a winemaker who wants this element in their wines can stop the fermentation when the aroma is at its peak.

While these buttery – and often sweet – Chardonnays had their time in the spotlight more than a decade ago, most premium winemakers now (myself included) are pushing for the vineyard site and fruit to be front and center. To make this happen, the wine can’t be clobbered by a cloying and easy-to-create buttery profile. Sign me up for the “hate it” category.

Thanks to Anthony Beckman of Balletto Vineyards for his insightful and thorough answer to the question of Where Does The Buttery Flavor in Some Chardonnay Come From?

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