HomeNorthern Grapes Project Owner’s ManualChapter 3: The Winery

Chapter 3: The Winery

Objective 3: Develop and optimize winemaking practices to sustainably produce and market distinctive, high quality wines from cold climate cultivars.

Assess yeast strains for selected cold-hardy cultivars.

Enologists conducted trials with select cold-hardy grape varieties to determine which yeast strains will work best with unique juice chemistry, using yeasts known to enhance desirable wine aromas.

Yeast Trials for Improved Wine Quality in Cold Climate Cultivars.  Seven cold-hardy grape cultivars (Brianna, Chancellor, Frontenac gris, Frontenac, La Crescent, Marquette, and Prairie Star) from Vermont and New York we fermented with different yeasts for 25 different wines.  Finished wines were then evaluated for sensory properties.
Anna Katharine Mansfield

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Optimize deacidification methods for cold climate cultivars.

High acidity of cold-hardy cultivars challenge even the most skilled winemakers.  Enologists evaluated biological and chemical methods to reduce acidity (reduce malic acid and retain tartaric acid) during the winemaking process.

Using Malic Acid-Reducing Yeasts for Cold Climate Wine Grapes.  Three yeast strains that purportedly metabolize malic acid at higher rates reduced total acidity in La Crescent wines and Frontenac rose wines.
James Luby and Andrew Horton, University of Minnesota. 

Optimizing deacidification methods for cold climate cultivars.  Studies indicate that pH has the greatest impact on malic acid loss.  In a scaled-up wine production trial, malic acid loss was slightly higher at ambient temperature in Frontenac gris, but under refrigeration in La Crescent.  No parameters were successful for preferential removal of malic acid.
Anna Katharine Mansfield and Chris Gerling, Cornell University 

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Skin contact trials on aromatic white cold hardy cultivars.

While regional and viticultural variables impact wine aroma and flavor, the final sensory profile is also influenced by processing.  Pre-fermentation skin contact treatments are used by winemakers to produce aromatic styles of white wines, but the effects of this have not been studied on cold climate varieties.  The goal of this work is to determine if pre-fermentation skin contact treatments on La Crescent and Edelweiss grapes have a positive impact on wine aroma.

Skin Contact Trial in La Crescent.  Researchers studied the effects of 24-hours pre-fermentation skin contact, at two temperatures, on the aroma intensity of La Crescent wines.
Murli Dharmadhikari, Jacek Koziel, Somchai Rice, Iowa State University, and Anna Katharine Mansfield, Cornell University

Edelweiss Skin Contact Trial. Murli Dharmadhikari, Erin Norton, Drew Horton, Iowa State University

Anthocyanins in red cold-hardy cultivars.

While extensive research has been performed on V. vinifera monoglucosides (anthocyanins, or pigments, that influence color in traditional red wine grapes), little is known about  diglucoside anthocyanin types and quantities in interspecific cold-hardy red hybrid grapes.  In these non-vinifera varieties, the structure of diglucoside anthocyanins make them less capable of binding in molecules that stabilize color, leading to atypical hues.

Bench-top anthocyanin kinetic experiments help researches describe color formation in red hybrid wines. Photo by Claire Burtch.

Characterizing anthocyanins in red cold hardy hybrids
While the color of cold-hardy red hybrids is different from that of traditional V. vinifera reds, little is known about the type and amount of anthocyanins in these cultivars.  This study characterized hybrid grape anthocyanins and found that diglucoside concentrations are higher than monoglucosides in hybrid grapes.  Higher diglucoside concentrations suggest different color hues of hybrid wines from traditional reds, and that color compounds are less likely to form expected stable, brick-red colors during aging.
Anna Katharine Mansfield, Cornell University

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Tannins

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Winery operations

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