Yiliang Cheng and Aude Watrelot*
*Iowa State University, 536 Farm House Ln, 2567, AMES, IA, 50011 (watrelot@iastate.edu)

One of the challenges of cold-hardy wines is their low concentration of tannins and high acidity, which leads to unbalanced wines, associated with low quality red wines. In a previous study, using the accentuated cut edges (ACE) technique on Marquette grapes showed an improvement of the concentrations of phenolics and tannins compared to a control and use of macerating enzyme. We hypothesized that the combination of those two techniques would help disrupt cell wall material and there­fore maximize extraction of phenolic compounds during the winemaking process. At crush, the Marquette musts were processed with ACE, followed by addition of pecti­nases, and were compared to a control and an ACE control without pectinases. Phe­nolic compounds such as tannins, anthocyanins, and other monomeric phenolics were quantified by HPLC-DAD/FLD and aroma compounds were quantified by solid-phase microextraction gas chromatography-mass spectrometry in wines at bottling and after six months of aging. The combination of ACE and pectinase addition signifi­cantly enhanced the concentrations of flavan-3-ols, tannins, polymeric pigments, and iron-reactive total phenolics at bottling. No difference in phenolic compounds content between treatments was observed during vinification, which suggested that ACE and pectinases had a limited effect on cell wall degradation, as evidenced by scanning electron microscopy analysis, and that chemical reactions most probably occur be­tween phenolic compounds over time. ACE and pectinases did not negatively impact the floral and fruity aroma attributes of Marquette wines at bottling. To evaluate how the combination of ACE and pectinases would help improve the quality of wines made from cold-hardy grapes, Marquette wines after aging will be sensory evaluated and compared with the chemical data.

Funding Support: No funding source