WINE TEACH-IN: 🍷WHERE DO AROMAS COME FROM IN WINE???🍷
Ever wondered why something smells as it does in your glass?
Typically 4 main sources, namely:
Aromas from Grapes
Aromas By Fermentation
Aromas From Fermentation and It's By-Products
and Aromas from Other Sources
AROMAS FROM GRAPES
Ever wondered where those herbaceous, grassy, peppery aromas come from in your glass of NZ Sauvignon Blanc? I know I have and they come from what's known as Methoxypyrazines, just like in a glass of Syrah/Shiraz or an Austrian Gruner Veltliner wines you may also get those lovely, delicious peppery notes too - from Rotundones.
Ok....but then what about all of the lovely, juicy fruit and floral aromas that I get in my wine.....
AROMAS BY FERMENTATION
So THIOLS are aromatic compounds released during the grape juice's fermentation period (getting slightly technical but still remaining with the Sav Blanc theme above - as an example 4MMP). Another example and probably best understand for most who are thinking about those floral and fruity aromas - these come from TERPENES again an aromatic compound.
OK...so that makes sense and that is it? No.
AROMAS FROM FERMENTATION AND IT'S BY-PRODUCTS
So then you also get aromas developing as by-products of the fermentation process such as lees (which are dead yeast cells). You also get what is known as ESTHERS which are compounds formed by the reaction of acids and alcohols, the majority of which are created through action of yeasts during fermentation. (Recall that yeast is eating the sugar content in the grape juice to produce alcohol). It is these Esthers that are responsible for a lot of the fresh, vibrancy and fruity aromas that end in your glass and are especially warranted when talking about young wines whose primary goal is to be drunk as soon as bottled rather than for ageing.
Going a step further, the most common Esther is ISOAMYL ACETATE - which typically gives us a few big clues based on the aromas it produces, one of which when in high concentration is banana which can be very reminiscent of the wines some of us probably tasted most recently in a bottle of Beaujolais Nouveau. Most Esthers are temporary or put another way, tend to be 'unstable' - it sounds like it is dangerous, but I promise it is not. More so that it will tend to fade after time - which is why when we talk of wines who are best drunk immediately, ie they are full of primary flavours like NZ Sav Blancs.
You do find other by-products, the other two to mention are things like ACETALDEHYDE which typically occurs when the wines has begun to oxidise the ethanol (alcohol) in the wine. This isn't always bad though, for example Fino Sherry gives off this type of aroma which is perfectly normal....but talking of Sherry is for another time and a future fortified wine teach-in. DIACETYL is another produced during fermentation producing buttery notes and yeast itself can also produce by-products.
AROMAS FROM OTHER SOURCES - eg Vanillin and Eucalpytol.
Feel free to discuss, message us if you would like to know more but herein ends the teach-in for today :)
Best Regards
The Devon Wine Guy
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