Abstract
Modifying the phenolic composition of Pinot noir wines can improve their quality, overcoming familiar challenges associated with deficiencies of color, tannin and ageing potential. During fermentation, extraction of desirable components from the skin takes place primarily through the inner skin surface of the berry and from broken skin edges. Ostensibly the extraction of phenolic compounds located in the skin may be enhanced by reducing the skin particle size. A theoretical analysis indicated that moderate fragmentation was sufficient to substantially decrease the surface area to perimeter ratio of grape skins. Three experiments showed that cutting grape skins into smaller fragments facilitated egress of color and tannin from the skin into the wine matrix. Homogenization of berry tissues resulted in a 6-fold increase in tannin, a 45% increase in stable pigment concentration, a 25% increase in wine colour density and a 20% increase in blue-purple coloration in wines at 6 months bottle age. Undifferentiated cutting of grapes caused a 6.5- fold increase in tannin, a 70% increase in stable pigment concentration, a 60% increase in wine colour density and a 10% increase in blue-purple coloration. Wines made using a cutting technique that reduced grape skins to 6% of their original size without damaging the seeds, were 3-fold higher in tannin, 95% higher in stable pigment concentration, had 50% greater wine color density and a 20% increase in blue-purple coloration. The effects of reducing skin particle size on phenolic extraction were found to be much greater than those achieved using pectolytic enzymes.
This innovative skin fragmentation technique has the potential to increase skin-derived red wine phenolics and is a viable alternative to maceration techniques currently used during winemaking.
- ©2015 by the American Society for Enology and Viticulture
Sign in for ASEV members
ASEV Members, please sign in at ASEV to access the journal online.
Sign in for Institutional and Non-member Subscribers
Log in using your username and password
Pay Per Article - You may access this article (from the computer you are currently using) for 2 day for US$10.00
Regain Access - You can regain access to a recent Pay per Article purchase if your access period has not yet expired.