Increasing light exposure to grape bunches has long been shown to influence the amount of phenolics in the fruit at harvest. In cool climates, increasing exposure is a particularly common practice due to the added benefit of allowing better disease control. For sparkling wines, phenolic composition is as important as the quantity, however little is known about the effect of increased bunch exposure on the phenolic profiles of the juice and wine. In this study, mature and lateral leaves were removed, up to and including the 4th node, at three different times in the 2011 and 2012 seasons (pre-flowering, pea sized berries and 50 % veraison) in Northern Tasmania with Pinot Noir and Chardonnay. Fruit composition parameters were measured and the phenolic profiles of base wines were analysed by spectral fingerprinting. Base wines were produced using standard protocol small scale winemaking (12 kg ferments). The phenolic fingerprint of base wines showed that strongest and most consistent separation by Principal Component Analysis (PCA) was between the pre-flowering leaf removal treatment and the control. This is despite a lack of difference in fruit quality or yield reduction. Spectra from caffeic and ferulic acid were compared, and with similar loadings at around 260, 310 and 330 nm, it can be postulated that hydroxycinnamates are driving the differences between these treatments.
History
Publication title
Proceedings of the 15th Australian Wine Industry Technical Conference (AWITC)
Department/School
Tasmanian Institute of Agriculture (TIA)
Publisher
AWITC
Place of publication
Sydney, NSW
Event title
The 15th Australian Wine Industry Technical Conference (AWITC)