I've had someone ask recently about 'buttery' wines and even though some readers may find the concept basic, this is, after all, Wine 101.
When I hear of a wine as being 'buttery', I think of it as having an aroma that smells like, well, butter, but it is sometimes also used to describe a creamy texture on the wine's palate. It's a term usually reserved for a richer white wine and almost exclusively when talking about one specific grape variety: Chardonnay. That being said, you can also find butter in many other wines like a modern white Rioja, white Bordeaux, even some Marsanne/Roussanne blends.
So where does it come from? One answer is oak. When white wines are aged in young oak barrels, sweet wood flavours are imparted into the wine. These often come across as vanilla and baking spice notes, but are sometimes associated with butter.
The other answer is diacetyl. Diacetyl is a component found in wine that is the byproduct of a process that happens after fermentation called malo-lactic conversion (also called malo-lactic fermentation, ML, or malo). Malo doesn't happen in all wine, it can be encouraged or prevented, depending on whether the winemaker sees it as complimenting the style of wine he or she has set out to make. During the process, malo-lactic bacteria converts malic acid (think about the tart, racy acid in a green apple) to lactic acid (the softer acid found in milk). The result of the malo-lactic conversion is softer acidity and a rounder texture in the wine. This often best compliments a richer, fuller-bodied white, particularly made from a grape like Chardonnay. As well as plain butter, people sometimes associate a wine that has gone through malo with notes of puffed wheat and popcorn (buttered, of course).
When these characters are overwhelming in a wine, they can come across as obnoxious or domineering, however, when integrated subtly, they can add complexities to a great wine. Below are two examples of fantastic Chardonnays available on My Wine Canada where the latter is true.
Jake Skakun is a writer and sommelier from Vancouver, currently living in Toronto. He can be found most days pulling corks and twisting caps at the Black Hoof. He Tweets and Instagrams @jakeskakun.