Wednesday, February 24, 2016

Vintage 2016 / Update 3

-Semillon harvested.
Baume 11.5°
pH 3.4 (satisfactory)
50ppm SO2* and ascorbic acid at crusher.
DAP added before yeast inoculation.
-Tempranillo harvested.
Baume 12.5°
pH 3.8 (high)
-Pinot Noir harvested.
Baume 12.3°
pH 3.9 (high)

Due to the small yield we crushed and then 'sulphured' the Tempranillo sealing it in a tank. We waited until the Pinot Noir harvest when we combined both varieties and fermented them together.
The red blend needed pH adjustment to 3.6 with tartaric acid.
Other additions apart from yeast were DAP and a MLF culture.
After 3 days the Semillon had not commenced fermentation. I went over my SO2 addition* and realized I had miscalculated and added too much.
Due to its antimicrobial effect this can retard fermentation or prevent it entirely.

So I decided to try the very tricky process of adding hydrogen peroxide. This converts the SO2 to a sulphate. It is also a very strong oxidizing agent and can ruin a batch of juice/wine very easily. So it is best to do it in stages while monitoring the resultant SO2 levels being careful not to reduce it to lower than 5ppm.
There is a specific formula and process for this operation. Details are here.
Then I added what was a 'stuck fermentation' level of yeast ie.4 times the normal, and fermentation started in 12 hours.
Note to self: be more careful with the maths next year!!!!
The Cabernet is enjoying some drier warmer weather and we don't expect to harvest until late March.

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