Best Practices for Dealing With Underripe Grapes
Last Updated: 9/2021
Applies to: Producers dealing with underripe grapes. Please download the complete guides which contain process and product recommendations.
Working with Underripe Grapes
The main issues in making wines from underripe grapes are vegetal aromas and flavors, high malic acid, and possibly deficient YAN. Additionally, in reds, lack of phenolic maturity can result in bitter/aggressive sensations and challenges with color.
Beyond the sensory impacts of underripeness, high malic acid has some potential fermentation consequences including:
- Juices/musts with high TAs (>15 g/L) and low pHs may not complete alcoholic fermentation.
- High lactic acid (>3 g/L) resulting from high malic acid (>6 g/L) can lead to stuck malolactic fermentation.
The degree of unripeness of your fruit is based on juice chemistry, juice sensory, and the physiological characteristics of your fruit prior to crush.
Assessing Physiological Underripeness
We recommend a rigorous berry sensory assessment. The Institut Coopératif du Vin method of berry sensory evaluation, developed by Jacques Rousseau, is a popular and excellent method for this. This method evaluates berries from 4 perspectives:
- Visual and tactile sensations: Color, berry firmness and ease of stalk removal
- Pulp assessment: Pulp firmness and adhesion to skin, sweetness, acidity and flavor balance (herbaceousness, fruitness)
- Skin tasting/maturity: Crushability, acidity, tannic intensity, drying, astringency and aroma
- Seed tasting/maturity: Crushability, color, tannic intensity, astringency and bitterness
The level of underripeness as determined by this method is relative and subjective. It is dependent on vintage conditions, varietal, site, and intended style.
Once you have assessed the level of underripeness that you're dealing with, download the following guides for:
- Winemaking advice and mitigation techniques
- Product recommendations where applicable