## 1 Introduction  
The business of grapes and wine generated over $7.5 billion U.S. dollars (USD) in the upper Midwestern states of Iowa, Illinois, Michigan, Minnesota, North Dakota, South Dakota, and Wisconsin in 2017 [1]. This included the direct economic impact from vineyard and winery activities as well as tourism, resulting in over 110,000 jobs and over $3 billion in wages (Table 1). In Iowa, the number of grape growers, vineyards of grapes, wineries, and wine production has increased in the last two decades (Figures 1 and 2) [2]. In a report by Tuck and Gartner in 2014, 100 hectares of grapes planted in Iowa were of the cold-hardy white varieties [3]. These numbers were extrapolated from self-reported surveys to determine the baseline of activity involving cold-hardy grape varieties. Of this estimated 100 hectares, 27% of the plantings were Frontenac gris and Brianna varieties. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**State**} & **Economic** & \multirow{2}{*}{**Jobs**} & **Wages 1** & **Vineyard** & **Winery** & \multirow{2}{*}{**Tourism 1**} & **Other 1,2** \\  & **Impact 1** & & & **Activity 1** & & **Activity 1** & \\ \hline North Dakota & \$135 & 2340 & \$57.3 & \$0.00680 & \$7.09 & \$0.245 & \$127 \\ South Dakota & \$180 & 2690 & \$62.4 & \$0.0719 & \$25.7 & \$1.69 & \$153 \\ Iowa & \$573 & 8760 & \$197 & \$1.10 & \$110 & \$29.0 & \$433 \\ Minnesota & \$979 & 15,400 & \$408 & \$1.22 & \$83.5 & \$21.3 & \$873 \\ Wisconsin & \$1320 & 20,700 & \$519 & \$1.12 & \$146 & \$39.7 & \$1130 \\ Michigan & \$1890 & 25,800 & \$710 & \$7.77 & \$325 & \$149 & \$1410 \\ Illinois & \$2480 & 34,800 & \$1060 & \$1.82 & \$247 & \$222 & \$2010 \\ \hline Totals & \$7550 & 11,0000 & \$3010 & \$13.1 & \$944 & \$463 & \$6130 \\ \hline \hline \end{tabular}  
* 1 Millions of U.S. Dollars (USD); 2 includes wholesale, retail, associations, research, and education.  
\end{table} 
Table 1: Economic impact of the U.S. Midwest (cold climate) wine industry [1]. Figure 1: The increase in hectares of wine grapes and the number of growers in Iowa [2]. There is continuous interest in understanding the chemical origin of grape aromas. Our working hypothesis is that this information could help growers and winemakers to determine a more targeted harvest date, based on the desired aromas. It also would allow an assessment of how various winemaking practices influence aroma, an important factor of wine quality. This information could streamline the production of new grape varieties by permitting the selection of varieties showing certain aromatic attributes. Despite these advantages, determining the chemical origin of varietal aromatic character is complicated. First, odor-active compounds in grapes often occur in nonvolatile forms. These compounds are released only upon crushing [4], through yeast metabolism [5], or during aging [6]. A varietal character can originate from a combination of compounds and not from varietal specific compounds. Extraction procedures may influence the stability of odor-active compounds. Identification and quantification of odor-active compounds are needed to understand the aroma potential of new cold-hardy grape varieties. The added benefit of simultaneous olfactory (O) and chemical analysis (e.g., by gas chromatography-mass spectrometry (GC-MS)) allows for characterization of trace amounts of compounds with detection limits below that of the mass detector (i.e., 2-isobutyl-3-methoxypyrazine, a \"green bell pepper\" aroma with detection threshold less than 0 ppb) [7,8]. Brianna is known, at least anecdotally within the industry, to develop an unwanted \"foxy\" aroma if harvested after 14-16 \({}^{\circ}\)Brix. However, there is a lack of scientific data to support this observation. Grape maturity levels expressed by sugar content (measured as \({}^{\circ}\)Brix) and titratable acidity (TA) in grape berries has a great impact on wine quality and aroma as well. During the period of grape ripening, sugar content increases in berries while the TA level decreases.