Suchergebnisse

Wine models with or without a dearomatised and lyophilized red wine extract containing a young red aroma base (control) plus one vector with one or several aroma compounds (unsaturated-aldehydes, saturated-aldehydes, benzaldehyde, isoamyl-alcohol, methoxypyrazines and (Z)-1,5-octadien-3-one) were prepared. Models were spiked with increasing amounts of acetaldehyde whose headspace concentrations were controlled. Odour and nasal chemesthesic properties were assessed by a trained sensory panel. Results confirm the contribution of the different players, notably isoamyl-alcohol, (Z)-1,5-octadien-3-one, benzaldehyde and methoxypyrazines, to wine aroma and tactile nasal characteristics and demonstrate that acetaldehyde levels play an outstanding role in their modulation. At low levels, it can play positive roles in some specific aromatic contexts, while at higher levels, enhance the negative effects associated to the generic presence of other aldehydes (saturated, unsaturated and Strecker aldehydes) by enhancing "green vegetable" notes and "itching" character and the "burning" effects linked to high levels of isoamyl alcohol. ; Funded by the Spanish Ministry of Economy and Competitiveness (MINECO) (project AGL2017-87373-C3, RTC-2015-3379 and RTC-2016-4935-2) and partly co-funded by the European Union (FEDER). I.A. acknowledges the MINECO for his predoctoral fellowship (FPU-2015). LAAE acknowledges the continuous support of Diputación General de Aragón (T53) and the European Social Fund. The authors also express their gratitude to the panellist for participating in the study. MPSN acknowledges the Spanish National Research Agency, the Ministry of Science, Innovation, and Universities and the European Social Fund for her postdoctoral fellowship: Ramón y Cajal Program (RYC2019-027995-I/AEI/10.13039/501100011033).

The orthonasal quality of two synthetic contexts of wine (young wine and oaked wine) spiked with six different levels of the Strecker aldehydes (isobutyraldehyde, 2-methylbutanal, 3-methylbutanal, methional and phenylacetaldehyde) was evaluated by a panel of wine experts. The aldehyde levels simulated the concentrations present in wines protected from oxidation during production and storage and after severe oxidation. Significant quality detriments were observed at concentrations of 13 Μg/L of methional, 49 Μg/L of phenylacetaldehyde, 17 Μg/L of isobutyraldehyde, 12 Μg/L of 2-methylbutanal and 24 Μg/L of 3-methylbutanal. The presence of these levels of aldehyde concentrations induced the reduction of fruitiness in young wines and of woody notes in oaked wines as well as the appearance of the typical attributes that define wine oxidation. More than 75% of recently opened commercial wines contain total levels of Strecker aldehydes higher than those, however their effect is not always noticeable as they are forming inodorous adducts with SO2. Nevertheless, this content is a potential risk for the shelf life of the wine, as once SO2 is depleted, these aldehydes could release back into their odour-active forms. Thus, in order to reduce the presence of Strecker aldehydes, eight different resins were studied (two scavengers, four mixed-mode anion exchange and two pure anion exchange) in white wine at two levels of SO2. After 24-h contact, the mixed mode Strata X-A resin was able to significantly reduce aldehydes' percentages: between 11% for isobutyraldehyde and 86% for phenylacetaldehyde. On the other hand, wine colour was affected and therefore the applicability of the treatment should be further studied. However, this work can be considered a starting point to solve the technological challenge involved in the elimination of aldehydes from wine. ; This work has been funded by the Spanish MINECO (Project AGL2014-59840 and AGL2017- 87373-C3-1-R) and partly cofounded by the European Union (FEDER). Founding from Diputación General de Aragón (T53) and Fondo Social Europeo is acknowledged

The use of non-Saccharomyces strains in aerated conditions has proven effective for alcohol content reduction in wine during lab-scale fermentation. The process has been scaled up to 20 L batches, in order to produce lower alcohol wines amenable to sensory analysis. Sequential instead of simultaneous inoculation was chosen to prevent oxygen exposure of Saccharomyces cerevisiae during fermentation, since previous results indicated that this would result in increased acetic acid production. In addition, an adaptation step was included to facilitate non-Saccharomyces implantation in natural must. Wines elaborated with Torulaspora delbrueckii or Metschnikowia pulcherrima in aerated conditions contained less alcohol than control wine (S. cerevisiae, non-aerated). Sensory and aroma analysis revealed that the quality of mixed fermentations was affected by the high levels of some yeast amino acid related byproducts, which suggests that further progress requires a careful selection of non-Saccharomyces strains and the use of specific N-nutrients. ; This work was supported by grants MINECO/FEDER RTC-2014-2186-2 (SOUNDWINE) developed in collaboration with Agrovin S.A., and AGL2015-63629-R, and EU project YeSVitE. (7FP-IRSES-GA n° 612441). JAC and PSN are the recipients of a MINECO Formación Postdoctoral contract from the Spanish Government. ; Peer reviewed