Atypical Aging Defect: Sensory Discrimination, Viticultural Causes, and Enological Consequences. A Review

Abstract

Atypical aging is an off-flavor that can occur in white wines within a period of a few weeks to one year after the first addition of sulfur dioxide postfermentation. Its sensory characterization is varied and controversial, including a premature loss of varietal aroma combined with an increase in off-flavors that comprise various attributes such as mothballs, furniture varnish, acacia blossom, wet wool, and dirty dish rag. Most research agrees on 2-aminoacetophenone and other less well-identified compounds generated by degradation of indole-3-acetic acid as the causal agents. This chemical pathway is controlled by the oxygen radical scavenging capacity of the wine, which, in turn, is highly influenced by viticultural stress factors as the ultimate cause. Although oxygen is involved, atypical aging is distinct from premature oxidative aging with its own set of sensory and chemical descriptors.

Impacts of depectinization of pear juice on alcoholic fermentation and indole formation

“…Previous research investigating mechanisms of indole formation have focused on metabolism of nitrogen‐containing compounds . While Arevalo‐Villena et al .…”

“…Alternatively, it is possible that compound(s) present in pear juice but absent in the synthetic medium were utilized for indole biosynthesis. For instance, catabolism of indole‐3‐acetic acid, a compound found in fruit juice, has been shown to yield indole and other compounds associated with atypical aging of grape wines . In these situations, selection of yeast strain is important given that some strains can produce indole (e.g.…”

“…Previous research investigating mechanisms of indole formation have focused on metabolism of nitrogen-containing compounds. 1,5,6 While Arevalo-Villena et al 6 provided evidence for the degradation of tryptophan yielding indole in grape wine, this amino acid was not present in any appreciable quantity in the pear juices (Table 2). Rather, the primary amino acid present in pear juice was asparagine which represented between 87.8% and 89.7% with lower concentrations of aspartic acid (5.1-5.8%) and cysteine, glutamic acid, isoleucine, serine, threonine, and valine (< 1.3%) also detected.…”

“…For instance, catabolism of indole-3-acetic acid, a compound found in fruit juice, [30][31][32] has been shown to yield indole and other compounds associated with atypical aging of grape wines. 4,5 In these situations, selection of yeast strain is important given that some strains can produce indole (e.g. MERIT) while others do not (e.g.…”

“…Indole can be synthesized during fermentation by yeast through different biochemical mechanisms. While catabolism of indole-3-acetic acid (IAA) can yield indole and other compounds associated with atypical aging of grape wines, 4,5 the taint may also be derived from the amino acid, tryptophan. As evidence, Arevalo-Villena et al 6 reported that indole concentrations were four times greater in grape wines when musts contained higher amounts of tryptophan present.…”