How Makes a Wine Grassy?
Ah, the inspiring scent of freshly mown grass. When Tesco launched a selection of 4 inexpensive wines labelled not by country or grape but by flavour, it was not the tempting-sounding Summer Pudding, Citrus Squeezer or Jam Pot that tumbled into trolleys, but a white sporting an image of a grass-cutter and the name Cut Grass.
It was made of sauvignon blanc and came from New Zealand, not a place I'd keep an eye open for the greatest value in my £4 bottle ; also, Loire sauvignon blanc is generally more clearly lush, while the green notes in an NZ sauvignon blanc have a tendency to be balanced with passion fruit and catty smells. But there had been some grassiness all right.
No, that's not another nugget of insanity mined from the tunnels of a wine writer's brain those grassy notes are no fancy of the imagination. "There are may be 2 hundred different smells in a wine," announces flavour chemist Bradley Strange, "so it depends which are far more outstanding. Grassiness comes essentially from the following aldehydes: hexenal, trans-2-hexenal and cis-3-hexenal, which are formed from the enzymatic cleavage [for those among us without chemistry A-level, that is the splitting of a compound under the action of an enzyme] of linoleic and linolenic acids, which are found in grapes and, particularly, unripe (i.e. green) grapes.
They have an inclination to be reduced to the reciprocal alcohols during fermentation.0020Cis-3-hexenal, particularly, is just about sweetly grassy. But it is the leftover aldehydes that drive the perception of grassiness for the straightforward reason that they are also found in grass. following wines chemically analysed, but my nose informs me you will find plenty of fresh, cool, summer field grassiness in Domaine Jacky Marteau Sauvignon Blanc 2009 (£6.49, Marks & Spencer; 14% abv). It has only just been bottled, is one of my buys for the season and will be in store any time now.
There also are clean, lean, green notes in Fox Hollow Hunter Valley Verdelho 2008 (£9.99, selected Marks & Spencer; 12% abv) an Australian that curls in the mouth like a smooth blade and, though unoaked, has a faint suggestion of toast and mingled with the nectarine and gooseberry flavours in Villa Maria Single Vineyard Taylor's Pass Sauvignon Blanc 2008, New Zealand (£13.49, Tesco; 14% abv). Therefore about that "catty" smells... "That comes from sulphur-containing scent chemicals," asserts Peculiar, "like para-mentha-8-thiol-3-one and 4-mercapto-4pentan-2-one. They've been identified in sauvignon Blanc, blackcurrants, passion fruit, and gooseberry and, I am sorry to tell you, cat's pee. So there we are.