Approaches to the classification of wine aroma aging potential. Applications to the case of Valpolicella red wines

Abstract

AIM: Unlike most of other foods, wine sensory quality is thought to reach a peak after an aging period. In the case of the Valpolicella red wines, the PDO regulation requires wines to undergo a minimum period of aging comprised between one and four years depending on the wine type. During this period many changes in wine composition take place, including significant modifications to wine aroma composition, through a wide range of acid hydrolysis reactions, cyclization, rearrangements and oxidations, that to date are only partly understood. Among these, hydrolysis of esters and glycosidic precursors is considered central to wine aroma evolution. Wines with higher content of precursors are expected to have greater aroma potential. However, acid-catalysed degradation also takes place during wine aging, so that the actual content of a given volatile compound after a period of aging is given by the balance between acid-driven release and degradation. The aim of this study was to investigate the fate of some volatile aroma compounds important for the sensory profile of Valpolicella wine.

METHODS: Different Valpolicella wines obtained from grapes harvested in different vineyards and vintages were submitted to two different ageing protocols. In one case wines were kept for 30 days at 16°C and 40 °C (Slaghenaufi et al. 2019) the latter simulating an aging of approximately one years. In the second case, harsher conditions were applied, consisting of 60°C (±0.2°C) for 0, 48, 72, and 168 (Silva Ferreira et al. 2003). Free volatile compounds and glycosidic precursors were analysed with SPE- and SPME-GC-MS techniques.

RESULTS: Several classes of compounds of varietal and fermentative origin like esters, terpenes, norisoprenoids and to a lesser extent of some benzenoids were affected by aging. In particular aged wines were characterized by increased content of 1,4- and 1,8-cineole, p-cymene and p-menthane-1,8-diol, branched chain fatty acids ethyl esters, TDN, TPB, vitispirane, and 2,6-dimethoxyphenol. The application of the harsh aging treatment allowed to highlight highly significant relationships between cineole occurrence in aged wines and linalool content of the young wine, in particular the ratio between glycosylated and free forms. Furthermore, most of acetic and ethyl esters were found to decrease with aging in an amount correlated to their initial content.

Conclusions

Occurence and amount of many compounds in aged wines was correlated to the composition of specific compounds in young wines. In particular in aged wines cineole occurrence was linked to linalool content, providing useful clues for the selection of young wines with specific aging attitude.

ACKNOWLEDGMENTS

Azienda Agricola f.lli Tedeschi is acknowledged for financial support