I’m often asked how wines attain their varied aromas and flavors. When we smell or taste lemon citrus, vanilla, blueberry, anise, pepper, tobacco and myriad other delights (some not so delightful!), are they present because the winemaker has added a dash of lemon or blackberry to the wine? How do they happen?
The short answer is that these aromas and flavors occur naturally in wine. The process of fermentation creates a complex stew of organic compounds and some of them are volatile. It is these volatile compounds which are chiefly responsible for wine’s scents and tastes. There are many groups of these naturally-occurring compounds but we’ll just cover a few of them; I’m not writing a textbook!
Esters: These are a form of organic acids responsible for many of wine’s flavors and aromas. They can be analyzed and replicated, which is one reason why we have the multi-billion dollar artificial flavor and aroma industries developing new food dishes and perfumes. For example, the scent of banana is the ester amyl acetate. If you could analyze and chart all the esters in a wine, some might be similar to the lemon citrus or blueberry notes wafting from the wine glass.
Aldehydes: Acetaldehydes give you that tang you find in many fino style sherries. Those vanilla notes you might observe in oak-treated wines are a type of benzaldehyde.
Terpenes: These are highly aromatic compounds. Those lovely smells of lychee and Alpine mountain flowers in Gewürztraminer result from terpenes.
Methoxypyrazines: A mouthful to say but this class of compound, found in Cabernet and Sauvignon Blanc, can give a wine herbaceous aromas; the grassiness of some Sauvignon Blancs or the green bell pepper scents of some Cabernets.
Sulfur compounds: In high concentrations they can be nasty and responsible for unpleasant compounds like mercaptans, which result from the presence of hydrogen sulfide in the wine. They can smell like a burnt match, cooked cabbage or geraniums – yecch!
This is just a brief, simple discussion of where wine’s aromas and flavors come from. There are many more important compounds I didn’t mention but you get the idea. These scents and tastes, in the right circumstances, give us the magic in wine.
If you’d like to explore this further, check out the book, “The Science of Wine from Vine to Glass” by Jamie Goode. It is an excellent primer on wine science and inspired this posting.