Location: Horticultural Crops Production and Genetic Improvement Research Unit
Project Number: 2072-21000-060-023-A
Project Type: Cooperative Agreement
Start Date: Sep 1, 2026
End Date: Dec 31, 2029
Objective:
This proposal directly addresses Northwest Center for Small Fruit Research wine processing research priority 1D through the following objectives:
Screen collection of Oregon indigenous vineyard yeasts to identify strains with potential to positively impact fermentation outcomes and Pinot Noir quality.
Determine environmental conditions and winemaking strategies that enhance impact of “potential positive” Oregon indigenous vineyard yeasts.
Validate impacts of Oregon indigenous vineyard yeasts on Pinot Noir fermentations, wine volatile aroma compound profiles and sensory properties.
Deliver workshop to stakeholders summarizing project outcomes and guidelines for optimizing impacts of Oregon indigenous vineyard yeasts.
Approach:
This project will utilize a collection of 283 yeasts isolated from Oregon Pinot Noir vineyards during previous research. The collection spans 15 species and includes strains commonly detected in Oregon Pinot Noir fermentations. Some species are associated with undesirable aromas, while others may positively influence wine quality. The project aims to identify indigenous yeasts that suppress undesirable yeasts and persist during fermentation, increasing their influence on wine aroma and flavor.
Objective a) will evaluate competitive interactions between indigenous vineyard yeasts, undesirable yeast populations, and a commercial Pinot Noir yeast strain under relevant fermentation conditions. Experiments will assess effects of temperature, sugar concentration, ethanol, pH, nitrogen availability, and sulfur dioxide on yeast competitiveness and persistence.
Objective b) will validate promising yeast strains and fermentation conditions in laboratory-scale fermentations. Microbial enumeration methods will be used to monitor persistence of beneficial yeasts and identify winemaking conditions most likely to increase positive impacts on Pinot Noir fermentation outcomes.
Objective c) will evaluate impacts on wine quality through laboratory-scale and pilot-scale Pinot Noir fermentations conducted in the Oregon State University Research and Teaching Winery. Fermentation performance, wine chemistry, and volatile aroma compounds will be analyzed to identify treatments that significantly influence Pinot Noir quality. Wines will also undergo sensory evaluation by a trained panel to assess aroma, flavor, and mouthfeel differences among treatments.
Objective d) will deliver a workshop for Oregon wine industry stakeholders that summarizes project findings and provides practical guidance for managing indigenous vineyard yeasts to improve fermentation outcomes and wine quality.
A potential challenge is that yeast strains identified as competitive in laboratory conditions may not produce measurable impacts in Pinot Noir fermentations. However, previous research supports the use of this screening and validation approach for identifying indigenous yeasts capable of influencing wine quality.