Final Report: June 2023

Principal Investigator: Jim Harbertson, Washington State University, Richland

Telephone: 509-372-7506

Cooperators: Katie Nelson, Chateau Ste. Michelle Wine Estates

Summary: Wine acidity has been identified as one of the principal chemical and sensory wine attributes to be impacted by climate change. Understanding how to alter our wines to achieve the sensory and chemical outcomes is key to remaining competitive on the global wine market. This was a one-year demonstration project funded through the Washington State Wine Commission.

Three acid adjustment experiments were conducted during the 2022 vintage. Acid was added early at the fermentor and later post malo-lactic conversion or pre-cold stabilization for a red and white cultivar (Cabernet Sauvignon and Chardonnay). An additional acid adjustment experiment was conducted varying the malo-lactic conversion with Chardonnay. Key findings include:

  • Effectiveness of acid addition on high pH wines that had undergone malolactic fermentation was impacted by timing. Changes seen in the early addition were not observed closer to bottling but late additions were obvious.
  • Early and late additions of acid on high pH wine that had not undergone malolactic fermentation were equivalent. 
  • Use of ion exchange to target wine titratable acidity and match pH wored effectively for the wines that underwent malolactic fermentation. Use of ion exchange may prevent further changes in wine acidity over time due to lower concentrations of potassium.
  • Formal sensory results were compromised but informal evaluation showed changes in sourness, which was related to changes in concentration for wines that underwent malolactic fermentation. Late acid additions were more sour than early additions as much of the acid added early was gone. 

 Read more by downloading the full report above.

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