Adjusting Acid, Sugar, Alcohol

Question 1

Chaptalization + Sugar adds

Answer 1

Mutage:

• Ch Ste Michelle uses a kind of ‘sussreserve’ to adjust sweetness. Each year they take a couple of tanks of must, add loads of sulfur, clarify, and chill. Filter once a month and keep the sulfur around 70ppm free. Is cheaper than chaptalization and keeps the flavor the same.
• Sussreserve fallen out of favor but importer Terry Thiese is a fan. He thinks is less stressful and more control than trying to freeze out a ferment in process.
• Chaptalizing illegal in California and Italy. Is legal in France but sometimes requires permission.
  Example: 2016 Ch Giscours got fined 200 million Euro for chaptalizing two tanks. The problem was one contained 20% Merlot and Merlot not allowed to chaptalize, and the other tank added 75kg instead of 25kg which put them over the permitted addition of 1% ABV.

Question 2

De-Alc-ing

Answer 2

Reserve Osmosis:

• Randy Dunn ROs all his Cabernets to at or under 14% ABV
• likely a $30,000 machine
• a type of cross-flow filtration
• complicated and difficult to operate

Spinning cone:
can be $1 million machinery
- separates the wine into volatile fractions, can remove ABV of a section of the wine, the rest is blended back in

Watering back:

• Adding water dilutes must so it is more common to bleed the amount of water you want to add
• typically accompanied by a slight addition of tartaric because water has a pH of 7 and must 3-3.5 so adding water is effectively de-acidifying

Question 3

Acidification

Answer 3

• Ch Ste Michelle acidifies their Chardonnay with tartaric right after pick to pH of 3.5
• Almost all Sherries are acidified
• Legally can be done through the addition of tartaric (strongest), citric, or malic (weakest).
• Tartaric is most common.
  
  • 0.5–1 g/l of tartaric acid is needed to shift pH by 0.1
  • Negative of tartaric is it can come out of solution later to form crystals
  • Positive is that, as it is a strong acid, little has to be used
• Citric is next common, but isn’t advised when MLF is planned as can cause diacetyl
• Some illegally add sulfuric acid because that is the strongest

Question 4

Acids

Answer 4

3 Main Grape Acids:
Tartaric - The primary wine acid and specific to grapes.

Malic - Weak acid.

Citric - Medium weak acid.

Other:
Other organic acids present in grapes include D-gluconic acid, mucic acid, coumaric acid and coumaryl tartaric acid. Further acids are produced during fermentation, such as succinic, lactic and acetic acids. In addition, ascorbic acid may be added during winemaking as an antioxidant.

Question 5

De-Acidifying

Answer 5

Add calcium carbonate

Example: Heidi Barrett at Napa Wine Co used to acidify her wines through elevage and then de-acidify prior to bottling in order to keep the wine safe from microbes