The New York Wine Census - Total Quality Focus

Methoxypyrazines and Green Flavors

Comprehensive GC - Mass Spectrometry (GCxGC-MS)

Flavors in Non-Vinifera Grapes

Stable Isotope Measurements in Complex Matrices

Graduate Students
  Imelda Ryona, Food Science, MS, 2007-current

Undergraduates
  Kerri Bailey (RIT), 2007

  Kristin Alongi (Hamilton), 2007

Modern analytical techniques such as GC-MS and LC-MS have given enologists a window into the fascinating complexity of wine chemistry. Approximately 1000 volatile aroma compounds have been identified in wine as well as hundreds of anthocyanins, flavanols, and other non-volatiles responsible for wine’s body, color, and astringency.  

Of particular interest are the compounds associated with "unripe" and "green" aromas.  In particular, methoxypyrazines (MP) may impart undesirable “green pepper” and “vegetative” characteristics to wines at breathtakingly low levels not far above their sensory threshold in wine (10 ng/L), especially in the so-called Bordeaux varieties (e.g. Cabernet Sauvignon, Cabernet Franc). High MP content is generally associated with insufficient sun exposure, short growing seasons, and excessive vegetative growth and therefore is of particular concern to cool climates like the Finger Lakes.  However, conflicting reports exist in the literature about the role of sunlight exposure in MP formation and degradation.  In collaboration with Justine Vanden Heuvel and Alan Lakso in Horticultural Sciences, we are interested in the factors responsible for MP synthesis and accumulation, and to understand where and when in the growing season this accumulation occurs.  We are also interested in developing means to selectively remediate wine and juice with high MP levels.  This information should assist cool-climate growers in producing high quality wines even in difficult growing seasons, as well as improving our general understanding of flavor development in grapes.

We are also interested in developing comprehensive 2-D gas chromatography – mass spectrometry (GCxGC-MS) as a tool for comprehensive analysis of grapes and wines produced under different conditions.  Because of its improved separation and sensitivity compared to conventional GC-MS, GCxGC-MS has the ability to rapidly distinguish subtle differences between complex mixtures in an unbiased manner.  These tools are particularly useful for taking a broad snapshots of samples where multiple changes are expected to occur.  Examples of ongoing applications range from profiling headspace volatiles in wines from different treatments to "viticultural metabolomics", where the goal is to understanding the multivariant changes that occur in grapes at the small molecule level.

In collaboration with Justine Vanden Heuvel (Horticultural Sciences) and Terry Acree (Food Science and Technology) our group is interested in the compounds responsible for the "hybrid off-aroma".  Hybrids of American grapes (V. riparia, V. rupestris, etc..) and European varieties (V. vinifera) are popular among Eastern and Midwest growers due their improved cold tolerance, disease resistance, and yield.  However, the ability of hybrids to deliver high price points is often limited by the presence of distinctive off-aromas related to their American parentage.  Identifying the compounds responsible for these aromas will assist in ongoing viticultural and breeding efforts to improve the quality of hybrid wine grapes.

Finally, we are interested in understanding the origin and flux of aromatic volatiles during fermentation and aging. Often, enological research focuses on measuring static levels of analytes of interest; that is, the concentration of the analyte at a particular time point in the grape growing or winemaking processes. With stable isotope tracers, it is possible to elucidate both the synthesis-degradation rates and precursors of a particular compound.  We expect this information will be useful for optimizing fermentations to preserve or avoid particular flavor profiles.

Professional Societies
 

American Society for Mass Spectrometry (ASMS)
American Society of Enology and Viticulture (ASEV)

Institute of Food Technology (IFT)

American Chemical Society (ACS)

Honors and Awards
Charles J. Quillman Jr. Fellowship, 2004
NIH Training Grant, 2003
NSF Graduate Fellowship (Honorable Mention), 2001
Cornell Graduate Fellowship, 2000