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Best Practices for Dealing With Underripe Grapes

Last Updated: 6/2021

Applies to: Producers dealing with underripe grapes. This article serves as an introduction to the complete guides which contain process and product recommendations.

The full best practices guides are available as pdf downloads at the end of the article.

Background

Among the many factors that influence grape ripeness are cultivar, vineyard management practices, climate and weather, soil, and the overall health of the vine. Other factors that may affect picking decisions are disease incidence, berry damage by birds, insects and animals, current and potential weather conditions, and logistics. At a minimum, ripeness assessment can be based on the sugar:acid balance and the phenolic maturity of the grapes. In some circumstances, we may have to harvest before the grapes have reached the desired maturity.

When dealing with under-ripe red fruit or grapes that taste vegetal due to the level of pyrazines and aldehydes, alternative and/or additional winemaking practices may be needed. Unripe fruit can result in limited extractability of the skin tannins due to thicker berry skins. It may also result in unripe seed tannins, lighter color, unbalanced mouthfeel, and diminished aromatic potential. The berry chemistry may also pose a challenge. The organic acid profile may affect fermentation choices. In under-ripe grapes, the YAN may not be sufficient to conduct a healthy and secure fermentation.

Quick Tips

Pre-fermentation:

  • Analysis is key! Berry sensory assessment and chemical analysis of must both be conducted to paint the full picture of the imbalance or underripeness you’re dealing with.
  • Eliminate MOG (material other than grapes) and stems as these can amplify herbaceous and green flavors
  • Treat the fruit gently throughout the process
  • Clarify pressed juice quickly and eliminate the press solids.Treat juice during settling to minimize and counterbalance vegetative flavors.

Fermentation:

  • Choose yeast and bacteria that optimize fruity flavors
  • Manage acid profile via both biological (malolactic fermentation) and chemical means
  • Ferment at a temperature that produces fruity secondary metabolites (esters)
  • Avoid using DAP as that will diminish the production of fruity flavors and promote the production of volatile sulfur compounds, which will heighten the green flavors
  • Mix the tank during the later stages of fermentation to keep the yeast in suspension and minimize yeast stress
  • Rack off fermentation solids as soon as possible


pdf Downloads

Red Grapes

Optimizing Wines made From Underripe Red Fruit

Download

White and Rosé Grapes

White and Rosé Winemaking from Underripe Fruit

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