Hormonal and associated metabolic changes in susceptible harvest-ripe grapes under asymptomatic and symptomatic Esca disease

AIM: Bonarda, the second red grape variety in Argentina, produces high yields per hectare generating, in several cases, wines with low levels of quality compounds.

The project REALISM (regionality and circular economy in food products to counteract the Metabolic Syndrome (M.S.)) was initiated to develop antioxidant-rich food products with the ability to reduce the risk of developing the M.S.

In recent years several strategies have been proposed to cope with the effect of climate change on grape berry quality but only a few studies have dealt with the influence of management practices implemented in the field (e.g. irrigation,summer pruning, etc.), on the evolution of wines over time. 

The aromatic quality of wines after a long aging period in bottle is one of key points for oenologists. The objective of this work is to determine the main representative aromatic compounds found in long aged wines from D.O.Ca. Rioja. This study was made by 32 wines from 1971 to 2010 vintages. Sotolon, acetaldehyde, phenylacetaldehyde, 1,1,6-trimethyl-1,2-dihydronaptalene (TDN), β-damascenone, Y-decalactone and Y-dodecalactone were determined as the most important oxidation markers by GC-MS analysis. Moreover, sensory analysis using triangular tests were performed from wines with and without the addition of the mentioned compounds. Four different concentrations of each odorant were added, as individual compounds and as mixtures. The additions were ranged from values close to the reference odour thresholds up to high level concentrations. The most identified aroma was sotolon, which is commonly associated to curry and coffee liqueur aromatic notes. Other oxidative compounds were easily detected by panellists, such as Y-decalactone (peach compote), Y-dodecalactone (ripe fruit). The mixtures of the odorants were most easily detected than the individual compounds. It should be noted that acetaldehyde and phenylacetaldehyde were rarely perceived and distinguished.

The chemical mechanisms involved in oxidation/reduction potential of wine during winemaking and aging are affecting its color, aroma and taste. Chemical oxidation is one of the major causes of development of off-flavors during ageing1. Thus, the chemical changes in wine during storage should be controlled to ensure the sensory quality of the product and avoid consumer rejection that will compromise the economic value of the product. The 1-hydroxyethyl radical has been recognized as the key radical intermediate in the oxidative reactions in wine2. Based on the kinetic study of POBN-1-hydroxyethyl spin adduct formation in wines initiated via the Fenton reaction, a novel tool was recently developed in our laboratory to quantify the resistance of wines against oxidation3.