Abstract
Rotundone was recently identified as the compound which imparts the black pepper aroma in several wine grape cultivars. This two-year study aimed to identify the presence of rotundone in Noiret (interspecific hybrid of Vitis) and to determine the impact of fruit-zone leaf removal on rotundone concentration in fruit and wine. The relationship between the intensity of black pepper aroma and rotundone concentration in Noiret wine was also explored. An undefoliated control (CON) was compared to a maintained fruit-zone sunlight exposure (MSE) treatment, where leaves were periodically removed from the fruit-zone. Influence of timing of fruit-zone leaf removal was assessed in a separate experiment by comparing pre-veraison (LR) and post-veraison leaf removal (PVLR) treatments. In 2015, MSE vines had greater fruit-zone sunlight exposure compared to the CON throughout the season, both at the pre- and post-veraison stages, whereas in 2014 only after veraison. PVLR increased fruit-zone sunlight exposure during ripening compared to LR in 2015 only. Rotundone could not be quantified in Noiret berries sampled before or at veraison (limit of quantitation = 0.16 μg/kg). In 2014, rotundone concentration in the harvested fruit and wines did not differ within either treatment comparison. In 2015, rotundone concentration was significantly higher in MSE (1.98 μg/kg) than CON (1.28 μg/kg) harvested fruit and resulting wines. Removing leaves after veraison (PVLR) temporarily increased rotundone concentration compared to LR, but differences disappeared by harvest. Black pepper aroma intensity as determined by a sensory panel was positively correlated (p = 0.023, r = 0.791) to rotundone concentration in wines made from imposed viticulture treatments, providing evidence that black pepper notes in Noiret are positively related to concentration of rotundone in the wine.
- Received November 2016.
- Revision received April 2017.
- Revision received June 2017.
- Accepted June 2017.
- Published online August 2017
- ©2017 by the American Society for Enology and Viticulture
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