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Atypical aging of white wines (ATA) is an off-flavour characterised by rapid loss of fruity aromas and the development of unpleasant odours. This study aims to evaluate the effectiveness of different oenological adjuvants (4-ethylcatechol, 4-methylcatechol, gentisic acid, hydroxytyrosol, ascorbic acid, glutathione, ellagic acid, gallic acid, galla tannin, ellagic tannin, quebracho, grape tannins) added to musts before fermentation for preventing the possible development of ATA. High resolution mass spectrometry made it possible to quantify and qualify free and conjugated IAA in wine at the end of the fermentation and subsequently 2-aminoacetophenone (AAP) was quantified after the force ageing period (6 days at 40 °C). Ascorbic acid was confirmed as the most appropriate antioxidant adjuvant which can be used for ATA defect prevention. With an almost comparable effect, gallotannin addition prevented AAP production to exceed 1 μg/L. A predicted model (ANCOVA) indicated that over 80% of the variability of potential AAP formation in wines was explained by the amount of precursors, grape variety and antioxidant treatment. Moreover, a suspect screening approach made it possible to study the kinetic formation and the consumption of the reaction metabolites formed during the oxidative degradation of IAA leading to AAP.

Sulfur chemistry remains one of the most intriguing and elusive fields in wine science. In particular, the possibility for symmetric and asymmetric glutathionylated and cysteinylated polysulfides to act as latent reservoirs for H2S warrants new research on the factors influencing the formation and accumulation of these molecules. The present research studies the impact of pre-fermentative additions of commonly employed antioxidants: glutathione, ascorbic acid, and ellagic tannin. Musts from four different white grape varieties (Riesling, Pinot gris, Pinot blanc, and Johanniter) were analysed using our comprehensive HPLC-HRMS method. Seven symmetric and asymmetric glutathionylated (G) and cysteinylated (C) polysulfides (GS2C, GS3C, GS4C, GS3G, GS4G, CS3C, and CS4C) were detected in the final 48 wine samples. Finally, this work describes for the first time the impact of an accelerated ageing of wine on the polysulfides present. All variables (Must, Treatment, and Time) were shown to impart statistically significant effects (p = 0.0001) in the PERMANOVA model. The PCAs based on polysulfides present in young and aged wine explained more than 80% of the total variance for each grape variety and showed that Asc or GSH additions have tend to produce lower levels of polysulfides in the resultant wines.

This study aimed to evaluate the effects of fermentation with lactic acid bacteria (LAB) on organic acids, ascorbic acid, phenolic compounds, anthocyanins, and carotenoids of sweet orange (Citrus sinensis) juices. Juices from ‘Tarocco’ and ‘Washington navel’ oranges were fermented at 30 °C for 48 h with L. plantarum, L. rhamnosus, L. paracasei, and L. brevis without supplementation. The juice from ‘Washington navel’ resulted the best medium to grow LAB, especially L. brevis (1.98 ± 0.36 log CFU mL−1 at 48 h). Malic acid was thoroughly converted into lactic acid. Ascorbic acid increased in ‘Tarocco’ juice, peaking to 295 ± 25.3 g L−1 when fermented by L. brevis. The effects of LAB on phenolic compounds were matrix-specific, e.g., L. rhamnosus increased the levels of phenolics in ‘Washington navel’ juice (36.8 ± 1.51 mg L−1; p