# Influence of Region on Sensory and Chemical Profiles of Pennsylvania Gruner Veltliner Wines
## 3 Results and Discussion
### Chemical Analysis
#### 3.2.3 Phenolic and Color Analysis  
In Year 1, relative abundance significantly differed by wine for the three phenolic compounds examined. Relative abundances of (\(-\))-epicatechin and (\(+\))-catechin also varied by region, however, gallic acid abundance did not differ between regions (Table S10). Regional differences were likely found due to (\(-\))-epicatechin being undetectable in NC wines, while (\(+\))-catechin was not detected in NC1 and SE5 samples.  
In Year 2 samples, relative abundance significantly differed for all compounds by wine; however, no compounds were significantly different by region (Table S10). NW2 was significantly higher in both gallic acid and (\(-\))-epicatechin than all other wines. NW1 and NW3 wines were lowest in all compounds ((\(-\))-epicatechin and (\(+\))-catechin were not detected in these samples), which may be due to limited cluster thinning at these sites. Clusters per vine counts at these sites were high (54 clusters per vine in Year 2). Cluster thinning is used to improve grape quality and control crop load in over cropping wines, and phenolic levels can increase in grapes when cluster thinning is employed [44; 45; 46]. It is likely that lack of adequate crop thinning at the NW1 and NW3 sites altered phenolic composition and resulted in lower phenolic concentrations in these wines.  
Although not significantly different by wine, the NW1 and NW3 samples still had the highest ratings of astringent mouthfeel in Year 2. Astringency can be caused by a number of compounds present in wines, including phenolics. However, high acidity can also lead to high astringency ratings in white wines regardless of total phenolic concentration [47]. NW1 and NW3 wines had the lowest pH and highest TA values of the samples, suggesting that astringency ratings were at least partially due to higher acidity levels and not concentration of phenolics.  
Colorimetric coordinates \(L^{\star}\), \(a^{\star}\), and \(b^{\star}\) were used to examine color variation among wine samples. In Year 1 wines, there was variation in \(L^{\star}\) for samples regardless of region. All but four replicates of SE wines and all but one replicate of NW wines had \(L^{\star}\) values higher than 99.00. NE wines and one replicate of NC wines had \(L^{\star}\) values less than 99.00. \(a^{\star}\) values also varied within region for SE wines, ranging from \(-\)0.37 to \(-\)0.81. NW wines generally had lower \(a^{\star}\) values than wines from other regions, ranging from \(-\)0.78 to \(-\)0.88. A clearer regional trend was seen in \(b^{\star}\) values, with SE and NC wines having \(b^{\star}\) values less than 3.00 and NW and NE wines having \(b^{\star}\) values greater than 3.00. These results are consistent with visual sensory evaluation, in which the trained panel found NW and NE wines to be significantly higher in yellow color than wines from the SE and NC regions.  
\(L^{\star}\) values generally similar across regions for Year 2, consistent with Year 1 results. All but 3 of 15 fermentation replicates had \(L^{\star}\) values measuring between 98.00 and 99.00. There was variation in \(a^{\star}\) measurements across wines, ranging from \(-\)0.40 to 0.03 for SE wines and \(-\)0.36 to \(-\)0.16 for NW wines. NW wines had the highest \(b^{\star}\) values ranging from 4.36 to 5.07. These results are consistent with visual sensory evaluation, in which the trained panel rated NW wines significantly higher in yellow color than other regions. The trained panel rated NC wines higher in yellow color than SE wines. However, \(b^{\star}\) values for NC wines were lower than those of SE wines.