## 3 Results and Discussion
### Wine Arona Profile by GC-MS
[7], isoamyl alcohol was only found in trace amounts in Marquette grapes from Quebec and was not detected in the wines produced from those grapes [7]. In contrast, isoamyl alcohol is one of the top five most abundant aroma compounds in Marquette wine made from grapes grown in Iowa, as reported in another study, although the exact concentration was not reported [23]. The last two categories of aroma compounds in Marquette wines are C\({}_{13}\)-norisoprenoids and terpenes, known for their floral, fruity, and citrus notes [4]. These compounds are typically associated with the primary aromas of wines, which originate from the grape itself rather than fermentation or aging processes. However, in this study, the aroma compounds within these categories, including \(\beta\)-damascenone, linalool, p-cymene, and \(\beta\)-citronello, were not affected by any of the wine treatments from a statistical standpoint. This suggested that ACE and maceration enzymes did not affect the extraction and perception of primary aromas from grapes. Marquette juice has been reported to contain a large amount of C\({}_{13}\)-norisoprenoids (11 ug/L, e.g., \(\beta\)-damascenone and \(\alpha\)-ionone) and terpenes (5 ug/L, e.g., linalool and geraniol) at harvest in Quebec, Canada [7; 28]. After 6 months of aging, the concentration of C\({}_{13}\)-norisoprenoids dropped to 2 ug/L and terpenes increased to 99 ug/L [7]. However, these compounds were not measured in either grape juice or red wine from Marquette berries grown in Iowa [8; 23]. In addition to the growing location, one possible explanation of the low response ratio of both C\({}_{13}\)-norisoprenoids and terpenes in our study could be due to variations in the winemaking process. For example, the previous study in Quebec included a cold soaking process prior fermentation, which may remarkably enhance the extraction of these aroma compounds, as both C\({}_{13}\)-norisoprenoids and terpenes are primarily located in grape skins rather than in the juice [7]. Consequently, these inconsistencies of aroma profile highlight the impact of winemaking techniques and growing locations on the aroma profile of wines made from the same grape cultivars. According to [PERSON] et al. [17], the use of ACE treatment slightly increased the response ratio of butanol (fruity, fusel, and spirituous odors) and ethyl butanoate (fruity, peach, black currant odors) in Pinot noir wine, while decreasing the ratio of ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, and ethyl 3-methylbutanoate (fruity odors). Overall, the extraction induced by ACE treatment also enhanced the wine aroma profile by increasing the intensity of fruit-like aroma compounds [17]. The observed increase in ethyl ester concentration in ACE-treated Pinot noir wine could be due to improved extraction of nitrogen compounds from the grape pulp and skin, which are thoroughly broken down following ACE treatment. This is important because the production of ethyl esters during fermentation is greatly affected by the concentration of nitrogen compounds and must solids [9]. However, the effect of ACE treatment on yeast assimilable nitrogen (YAN) has not been evaluated in either previous research or our study, as it was not the main point of focus. Furthermore, the variation in yeast strain used in previous study on Pinot noir (Lalvin RC212\({}^{\text{TM}}\)) and our study on Marquette (ICV D254 yeast(r)) could be a contributing factor to the observed differences in the modification of ethyl ester profile during winemaking. [PERSON] et al. [29] demonstrated that the enzymatic activity of pectinase, which includes enzymes like polygalacturonases, pectin methylesterases, and pectin lyase, break down pectins of the cell walls. This modification of grape cell walls leads to an increase in the aroma precursors (e.g., hexanoic acid, octanoic acid, and isoamyl alcohol) and consequently results in the increase in aroma compounds (e.g., ethyl hexanoate, ethyl octanoate, isoamyl acetate) in Shiraz wine.