In February this year I wrote about the upcoming 2011 harvest “another problem fungus is botrytis or grey rot or bunch rot. Botrytis cinerea results in a disintegration of grape berry structure and creates the ideal conditions for the infection of the fruit with yeasts and bacteria which increase volatile acidity and laccase activity.
The musts obtained from infected grapes are strongly compromised both microbiologically and chemically. This shows up as laccase enzymes, a high concentration of apiculated yeasts, acetic bacteria, lactic bacteria and high concentrations of gluconic and acetic acid.
The most important wine making problems are caused by the presence of laccase, an enzyme that oxidises wine polyphenols.
As an indirect consequence it causes the production of acetaldehyde, the reduction of the free sulphur dioxide, an increase in "faded" aromatics, the loss of primary aromas, the darkening of white wines, and an increase of orange notes in red wines.
So we have a bit of a battle on our hands this vintage to produce reasonable wine”
Then in March, post harvest, I wrote about the Semillon, “the fruit has been affected by botrytis much of which we managed to manually sort through and discard. It will be interesting to see if that fungus has any affect on the resultant wine quality particularly its oxidation 'resistance'.”
Well the chickens have well and truly come home to roost.
Despite increased levels of sulphur, maintenance of a low pH and as best as possible reducing the exposure of the wine to air during the various production procedures, the smell of acetaldehyde (sherry like) and a noticeable browning in colour is obvious.
The wine has become victim of oxidation almost surely caused by laccase enzyme activity.
Unfortunately it has become undrinkable and will have to be poured into the ground.
That’s the risk of a Vin de Garage operation with no real sophisticated quality control equipment available.
Better luck in 2012.
And for all those inquiring about the welfare of the 'assisted birth' calf I blogged about last month, I have included a pic taken a few days ago.
Both baby and mother are doing well. So that more than cancels out the disappointment of the loss of the wine.