Yu-Te Tseng, Emma Sherman, Charles Brenneman, Claire Grose, and Anita Oberholster*
*University of California Davis, 3146 Robert Mondavi Institute - North, Davis, CA 95618 (aoberholster@ucdavis.edu)

The mouthfeel of red wine is directly related to its phenolic composition, which is affected by grape maturity. Sequential harvesting was used to make different wine styles from the same vineyard and to explore markers that can be used to indicate optimal ripeness for a given wine style. This was achieved by making wines from grape skins and seeds with different maturities while using a common base juice (20 Brix base juice from the same vineyard block chaptalized to 23 Brix). This kept the basic chemical composition (matrix) of the wines (referred to as juice-skins wines) constant, with mainly phenolic ripeness differences. These wines were compared with control wines made using standard winemaking practices. Pinot noir grapes were harvested at 23 and 25 Brix and pressed gently to remove the juice to substitute with the base juice. Basic chemical composition and phenolic and tannin compositions of grapes and wines were determined by the Adams-Harbertson assay, RP-HPLC, phloroglucinolysis, and gel permeation chromatography. Multivariate statistics were used to relate compositional data to descriptive analysis. Wines made with more mature grapes contained higher concentrations of monomeric and polymeric phenols; however, no significant differences in monomeric anthocyanins were observed. Juice-skins wines had lower polymeric phenol concentrations than control wines, and this difference increased when wines were made with fruit with greater maturity. Mouthfeel attribute “hot” and “persistence” and “dark fruit” aromas mainly described the wines made from higher maturity fruit. The study showed that wines made with riper fruit, irrespective of must sugar content, were characterized by greater phenolic content and ripe fruit characters.

Funding Support: Bragato Research Institute (New Zealand grape and wine research)