Determining Harvest Date and Leaf Removal Impact of Grüner Veltliner Using Aroma Profiles
Open Access
- Author:
- Nguyen, Anna
- Area of Honors:
- Food Science
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Misha T Kwasniewski, Thesis Supervisor
Federico Miguel Harte, Thesis Honors Advisor - Keywords:
- Gruner Veltliner
Harvest date
Leaf removal
White grape
Pennsylvania - Abstract:
- The influences of harvest date and leaf removal on aroma compounds of Grüner Veltliner (Vitis vinifera; GV) grown at Galen Glen winery located in Pennsylvania were examined. These grapes were harvested in 2021 as part of a field study conducted by Adams (2021) on yield components, fruit composition, and economic cost in response to harvest date and leaf removal. In this research, the obtained berries were used to evaluate changes in aroma compounds known to be important in this cultivar, specifically isoamyl acetate, hexyl acetate, 1-hexanol, ethyl octanoate, and linalool as a result of harvest schedule, leaf removal timing, and leaf removal severity levels. It is hypothesized that the grapes harvested according to the winery’s standard would produce wines of highest levels of aroma compounds compared to those that were harvested early. However, if combined with early leaf removal, early harvest grapes could have comparable levels of aroma compounds compared to late harvest grapes. The frozen grape juice was vinified using standard method to prevent introducing unaccounted variables, and aroma compound analysis was performed via headspace – solid phase microextraction – gas chromatography – mass spectrometry (HS-SPME-GC-MS). Finally, one-way and two-way ANOVA tests were conducted to determine if there was any significant relationship existed between harvest schedule, leaf removal timing, and leaf removal severity, in addition to their effects on the chosen aroma compounds’ concentrations. Harvest schedule was found to have a significant effect on the mean concentrations of isoamyl acetate, hexyl acetate, 1-hexanol, and ethyl octanoate. However, when combined with leaf removal timing, harvest schedule only significantly impacted the mean concentrations of hexyl acetate and 1-hexanol, and the treatments that received early leaf removal were observed to contain higher concentrations of these compounds compared to their late leaf removal counterparts. Linalool mean concentrations were not impacted by harvest schedule, leaf removal timing, leaf removal severity, or their combinations. Hence, if the compound of interest is linalool, it would be acceptable to harvest GV grapes earlier to avoid frost damage and fungal diseases.