Sensory impact of acetaldehyde addition in Syrah red wines

Abstract

Acetaldehyde is a volatile carbonyl compound synthetized by yeast during alcoholic fermentation, but it can also be formed by oxidation of ethanol during wine aging [1]. At low concentration, it enhances the fruity aroma, however, at higher levels, it can generate the appearance of notes of bruised and rotten apple [2]. From a chemical point of view, acetaldehyde is a reactive low-molecular-weight compound that can strongly bind sulfur dioxide but also phenolic compounds and amino acids to a lesser extent. Therefore, the sensory perception of a wine is the result of complex interactions between many volatile and non-volatile compounds [3]. Acetaldehyde is no exception to this rule and its perception depends on the wine matrix in which it is found.

In this work, two Syrah red wines with different polyphenol contents, spiked or not with acetaldehyde, were used to study the impact of this compound on olfactory perception. Free acetaldehyde levels (HS-GC-MS) were measured to determine the acetaldehyde combination levels in the spiked wines. A descriptive analysis of the wines was then performed by using a trained sensory panel and a Hierarchical Check All That Apply (HCATA) analysis of the samples with or without acetaldehyde addition. 

Significant differences were observed for both the sensory threshold and acetaldehyde combination for the wines. The results showed that some cited characteristic sensory descriptors (bruised and oxidized apple) varied significantly between the control wines and those with acetaldehyde addition. In the samples with increasing acetaldehyde levels, the cited descriptors were similar and not dependent on the concentration of acetaldehyde addition. Moreover, it was observed that, depending on its concentration, acetaldehyde amplified or hid descriptors. The increase of its concentration also leads to an increase of the frequency of citation of “vegetal” notes. However, its impact differed depending on the wine matrix, especially their polyphenol content.

[1] Wildenradt, H. L., & Singleton, V. L. (1974). The Production of Aldehydes as a Result of Oxidation of Polyphenolic Compounds and its Relation to Wine Aging. American Journal of Enology and Viticulture, 25(2), 119‑126.

[2] Waterhouse, A., Sacks, G., & Jeffery, D. (2016). Understanding Wine Chemistry (Wiley).

[3] Francis, I. L., & Newton, J. L. (2005). Determining wine aroma from compositional data. Australian Journal of Grape and Wine Research, 11(2), 114‑126.