Compositional And Sensory Analysis Of Finger Lakes Riesling
As the wine world continues to globalize, and industry competition grows, wine regions have increasingly focused on promoting one or two grape varietals which result in consistently expressive wines that best represent the viticultural area. A variety of studies have concentrated on defining regional cultivar typicity not only to enhance marketing techniques, but also to increase the understanding of a specific cultivar within the region from viticultural, enological, and sensorial perspectives, and findings may be relevant to the entire field. The Finger Lakes region of New York State has put itself on the world wine map through production of Rieslings with definitive sensory character. Preliminary assessments also suggest unique sensory profiles exist in the Rieslings according to which Finger Lake the grapes are cultivated. The sensory properties of Finger Lakes Rieslings, and the presence of subregional character, have not previously been investigated through rigorous, formal sensory analysis. This experiment sought to determine whether Riesling grapes grown along Keuka, Seneca, and Cayuga Lakes and from two distinct clones produced wines with unique sensory and compositional profiles. Six similar blocks of Riesling were selected to reduce effects of viticultural practices on compositional and sensory outcomes. Two sites, exclusively planted with clone 90 or clone 239, were selected from the east side of each lake. Viticultural treatments were standardized throughout the growing season. Inherent site and seasonal characteristics were recorded, and specific vine physiology and status measurements were collected from each block. Grapes were vinified, in duplicate lots from each site, by a standard winemaking protocol to yield two fermentation replicates. Instrumental analyses (GC-FID and GC-MS) were performed to quantify selected volatile aroma constituents of the Riesling wines. Generic descriptive analysis (DA) was performed on the wines by eleven panelists, screened for white wine consumption habits and sensory acuity. Sensory reference standards were developed during training and utilized along with intensity standards during orthonasal evaluation of the wines. Wines were also analyzed by HPLC for phenolic acids profiling. Statistical analyses of the volatile data showed that significant differences existed among some compounds. However, most of these differences were likely of no biological significance based on similarity of overall volatile profiles and vineyard site characteristics such as canopy light environment, vine water status, and crop load, factors which may impact wine quality. Monoterpene and TDN levels were at or below sensory threshold, and linalool was the only compound with apparent correlation to sensory data. DA panelists established 11 aroma attributes important to Finger Lakes Riesling wines. Wine aroma profiles were similar across vineyard sites, and two-way ANOVA results of lake, clone, and their interaction were not significant. Citrus, pineapple, linalool/floral, melon, and stemmy were among the descriptors present at the highest intensities. Phenolics data were characteristic of white wines as hydroxycinnamic acids and their tartrate esters dominated the profile. Higher concentrations of fertaric acid than coutaric acid were observed. While ANOVA showed significant results for lake, clone, and their interactions, clone had the strongest effect. These experiments indicate that sensory and aroma profiles of Riesling wines were similar despite differences in clonal material and growing conditions. However, the importance of seasonal growing conditions should not be overlooked as this experiment should be repeated over multiple years. The Riesling wines were also analyzed with less than six months of bottle age, and aging has the potential to impact wine differentiation. This sensory and volatile data is among the first to be reported for Riesling in the Finger Lakes. Riesling clone may be of interest to growers and winemakers due to effect on phenolic profile which may impact volatile stability and oxidative browning.
Riesling; descriptive analysis; phenolic acids; aroma chemistry; Finger Lakes
Mansfield, Anna K.
Vanden Heuvel, Justine E.
Food Science and Technology
M.S., Food Science and Technology
Master of Science
dissertation or thesis