Yiliang Cheng and Aude Watrelot*
*Iowa State University – Department of Food Science and Human Nutrition, 2567 Food Science Building, 536 Farm House Ln, Ames, IA 50011 (watrelot@iastate.edu)

Accentuated cut edges (ACE) and macerating enzyme are a mechanical and a bio- logical process that breaks grape skins into small fragments and breaks down skin cell wall polysaccharides, respectively. Both winemaking techniques have shown an enhancement of extractability of skin-derived phenolic compounds from Vitis vinifera grapes. However, the role of phenolic compounds and cell wall material on phenolic compound extraction and red wine quality are still unclear. In this study, Marquette red wines were made under three treatments applied at crush: control, ACE, and pectic enzyme (ENZ). The wine collection was processed throughout the winemaking process up to bottling. The wine hue and color intensity were evaluated using a UV-visible spectrophotometer. The composition of monomeric polyphenols was analyzed by RP-HPLC with diode array and fluorescence detectors. The concentration of flavan-3-ols and anthocyanins increased during fermentation and reached the highest concentrations at bottling. Flavonols and hydroxycinnamic acids had the lowest con- centration in wines. At bottling, ACE-treated wine showed the greatest color intensity, followed by ENZ-treated wine, and both treatments showed a significant decrease in hue compared to control wine. ACE treatment significantly increased the concentration of flavan-3-ols and hydroxycinnamic acids. There was no significant difference in the concentrations of anthocyanins and total phenolic compounds content among all treatments. The greater color intensity of treated wines suggested that some polymeric pigments were formed during winemaking. To investigate the role of these treatments, ACE and enzymes, on skin tannin extraction, further work will focus on condensed tannin content and chemical structure in control and treated wines.

Funding Support: N/A