Saturday, February 13, 2010

Vintage 2010 Begins

We had around 80mm of rain in the first week of February. Not enough to produce any run off but plenty to get the botrytis fungus (grey rot) going in the grapes. It is especially difficult to control even with protective sprays in grape varieties with "tight" bunches ie. where the grape berries are pressing up against one another eg. Pinot Noir, Semillon, Chardonnay etc. Any excess swelling caused by water absorption (through the vine roots) can cause the berry to split and the fungus to take hold. There was also some concern that the rain might have also diluted the juice but I had a theory that the soil is so dry it would be absorbing the water and binding it quicker than the grapes roots could take it up. So we picked the Pinot Noir on a hot (30° C) and steamy (95% RH) day before the next rain event which had been forecast in a few days time. There was some botrytis but nothing serious. It seemed to be in patches. This may be because of the uneven budburst and that when these particular vines were sprayed, along with the rest of the vineyard, they had already passed the critical spray time criteria ie. at 80% capfall and just before bunch closure.

Baume reading was 12.0° so my dilution theory could have been right. Who knows!
We crushed and inoculated with a yeast culture that evening. It was bubbling away less than 24 hours later. The smell of fermenting Pinot Noir is like violets. Wonderful!
So we are out there every 4 hours or so ‘punching’ the cap down ie. mixing the skins that rise to the surface, because of the carbon dioxide evolved, back into the fermenting juice. This increases the extraction of colour and tannins as well as prevents skin oxidation.
The following day we hit the Semillon. Another really sultry day and again some evidence of botrytis so we were right to pick. I added the slightly unripe fruit from some ‘rogue’ Chardonnay I have growing in my Cabernet Sauvignon block. They came inadvertantly with the original cuttings and despite my lame attempts over the years to graft Cabernet onto them, they remain Chardonnay. I don’t spray the Cabernet block for botrytis (the chemicals are a bit 'nasty' to use when not really needed) and this was obvious from the condition of some of the Chardonnay bunches. The really bad ones were cut and dropped.

Botrytis (Botrytis cinerea) is a problem in winemaking because the fungus imparts an oxidative enzyme, Laccase, to the juice. It is resistant to sulphur, oxidises many phenols, is stable in wine and can bring about serious and permanent browning and oxidation. Split grapes also encourage other damaging moulds and yeasts as well as acetic acid bacteria (vinegar!).
Of course there are two sides to every story and botrytis, when called and performs as ‘noble rot’, imparts desirable characteristics to some of the world’s great sweet dessert wines. Unfortunately the climatic conditions in our area are seldom really conducive for this situation to occur. However a neighbour of mine made some botrytis Chardonnay last year and won a bronze medal for it at this year's wine show.
The Semillon was crushed that afternoon and after letting the added pectin enzymes do their juice extraction task, we pressed and transferred the juice to a stainless steel tank. This year we only pressed lightly so the wine will be mainly based on free run juice. I thought because of the low Baume 10.0° (and thus 10% alcohol wine), a minimum of extracted phenolics would enhance the wine.

The yeast culture was rehydrated and added. Because sulphur was added (50ppm + 50ppm ascorbic acid) during the crushing process to protect the juice from oxidation, fermentation will be delayed for a while. Once the sulphur starts getting bound and the ‘stronger’ yeast cells take over then we should see some action in the next 24-36 hours.
That was a 10 hour day of hard work for the co-driver and me. Not only does it involve picking and processing but pre crush equipment cleaning and disinfecting and the post crush clean up.
As a result we fell into bed pretty early, fairly much exhausted.
Harvest Festival 'drinkies' would have to wait until another time.

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