title: Relationship of Soluble Grape-Derived Proteins to Condensed Tannin Extractability during Red Wine Fermentation.
abstract: In red winemaking, the extractability of condensed tannins (CT) can vary considerably even under identical fermentation conditions, and several explanations for this phenomenon have been proposed. Recent work has demonstrated that grape pathogenesis-related proteins (PRPs) may limit retention of CT added to finished wines, but their relevance to CT extractability has not been evaluated. In this work, Vitis vinifera and interspecific hybrids (Vitis ssp.) from both hot and cool climates were vinified under small-scale, controlled conditions. The final CT concentration in wine was well modeled from initial grape tannin and juice protein concentrations using the Freundlich equation (r2= 0.686). In follow-up experiments, separation and pretreatment of juice by bentonite, heating, freezing, or exogenous tannin addition reduced protein concentrations in juices from two grape varieties. The bentonite treatment also led to greater wine CT for one of the varieties, indicating that prefermentation removal of grape protein may be a viable approach to increasing wine CT.
authors.affiliation: Department of Food Science, Stocking Hall, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Lindsay F
authors.initials: LF
authors.lastname: Springer
authors.affiliation: Department of Food Science, Stocking Hall, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Lei-An
authors.initials: LA
authors.lastname: Chen
authors.affiliation: Department of Food Science, Stocking Hall, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Avery C
authors.initials: AC
authors.lastname: Stahlecker
authors.affiliation: E & J Gallo Winery, Modesto, California 95354, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Cousins
authors.affiliation: Department of Food Science, Stocking Hall, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Gavin L
authors.initials: GL
authors.lastname: Sacks
mesh_terms: D002980:Climate; D005285:Fermentation; D000067030:Fruit and Vegetable Juices; D010940:Plant Proteins / Q000737:chemistry*; D012995:Solubility; D013634:Tannins / Q000737:chemistry* / Q000378:metabolism; D027843:Vitis / Q000737:chemistry* / Q000378:metabolism; D014920:Wine
chemical_list: D010940:Plant Proteins; D013634:Tannins
keywords: astringency; condensed tannin; protein precipitation; protein−tannin interaction; tannin extraction; wine flavor; winemaking