Environmental Factors and Seasonality Affect the Concentration of Rotundone in Vitis vinifera L. cv. Shiraz Wine

Abstract

Rotundone is a sesquiterpene that gives grapes and wine a desirable ‘peppery’ aroma. Previous research has reported that growing grapevines in a cool climate is an important factor that drives rotundone accumulation in grape berries and wine. This study used historical data sets to investigate which weather parameters are mostly influencing rotundone concentration in grape berries and wine. For this purpose, wines produced from 15 vintages from the same Shiraz vineyard (The Old Block, Mount Langi Ghiran, Victoria, Australia) were analysed for rotundone concentration and compared to comprehensive weather data and minimal temperature information. Degree hours were obtained by interpolating available temperature information from the vineyard site using a simple piecewise cubic hermite interpolating polynomial method (PCHIP). Results showed that the highest concentrations of rotundone were consistently found in wines from cool and wet seasons. The Principal Component Analysis (PCA) showed that the concentration of rotundone in wine was negatively correlated with daily solar exposure and grape bunch zone temperature, and positively correlated with vineyard water balance. Finally, models were constructed based on the Gompertz function to describe the dynamics of rotundone concentration in berries through the ripening process according to phenological and thermal times. This characterisation is an important step forward to potentially predict the final quality of the resultant wines based on the evolution of specific compounds in berries according to critical environmental and micrometeorological variables. The modelling techniques described in this paper were able to describe the behaviour of rotundone concentration based on seasonal weather conditions and grapevine phenological stages, and could be potentially used to predict the final rotundone concentration early in future growing seasons. This could enable the adoption of precision irrigation and canopy management strategies to effectively mitigate adverse impacts related to climate change and microclimatic variability, such as heat waves, within a vineyard on wine quality.

On-vine grape drying combined with irrigation allows to produce red wines with enhanced phenolic and rotundone concentrations

“…The highest rotundone concentrations were found in wines made from vines experiencing low water deficit within the same vineyard (Geffroy et al, 2014). Other works showed that rotundone concentration was positively correlated with vineyard water balance in wines produced from 15 vintages and from the same Shiraz vineyard (Zhang et al, 2015b).…”

Fortification and Elevated Alcohol Concentration Affect the Concentration of Rotundone and Volatiles in Vitis vinifera cv. Shiraz Wine

“…Rotundone, an oxygenated bicyclic sesquiterpene in grape berries, is unlikely to undergo modification during fermentation, and remains chemically unchanged from the grape to the wine [3][4][5]. Rotundone is responsible for the attractive "pepper" character in grape berries and wine, and is especially important for cool-climate Shiraz (Syrah) [6][7][8]. It is possible to manipulate the concentration of this compound in wine by increasing rotundone production in grape berries [8][9][10][11][12][13][14][15][16][17][18][19].…”

“…Large variations in the concentration of rotundone have been observed within vineyards, between vines and within bunch regions, with more rotundone produced in areas having a southerly aspect, higher canopy cover and shading of bunches [16]. These factors explain how lower bunch zone air temperature, lower berry surface temperature, less direct solar exposure and higher precipitation are associated with elevated rotundone production [8,10,16]. Higher irrigation together with on-vine drying has been proven as an effective viticultural technique to improve rotundone concentration in the resultant wine [11].…”

“…The concentration of rotundone in grape berries increases gradually after veraison [8,10] and applying a plant growth regulator to grapevine to manipulate grapevine phenological development delays grape ripening and harvest, and therefore increases the concentration of rotundone in grape berries [9]. Higher grapevine vigour is associated with more shading in the fruit zone and higher leaf to fruit ratio.…”

Changes in concentration of volatile compounds in response to defoliation of Muscat of Alexandria grapevines grown under a traditional farming system

“…Vineyard microclimatic data, including visible light radiation and canopy temperature were also shown to be good indicators of the final grape quality (Zhang et al, 2015). A particular feature of 'Muscat of Alexandria' in the Itata Valley (Biobío Region, Chile) is the use of the gobelet (or bush vines) training system, which does not have a permanent structure to allow the arrangement of shoots to improve light interception and grape yield.…”