Yeasts Induce Acetaldehyde Production in Wine Micro-oxygenation Treatments

Abstract

Micro-oxygenation (Mox) is a common technique used to stabilize color and reduce harsh astringency in red wines. Here, we investigate the role of residual sugars, phenolics, SO 2 , and yeast on the oxidation of wine in three studies. In a Mox experiment, populations of yeasts emerged after the loss of SO 2 , and this was associated with sharp increases in oxygen consumption and acetaldehyde production. No acetaldehyde production was observed without the presence of yeast. In an oxygen saturation experiment, unfiltered wines, in particular those with residual sugar >3 g/L, consumed oxygen more quickly and produced more acetaldehyde than filtered wines. In a final experiment, the reincorporation of oxygen and glucose immediately after the completion of fermentation of an otherwise dry synthetic wine resulted in significant acetaldehyde production. These experiments highlighted the importance of yeast metabolism in determining a wine's response to Mox and suggested that the role of chemical oxidation to produce acetaldehyde during Mox may not be very important. It appears that control of microbial populations and residual sugar levels may be key to managing Mox treatments in winemaking, and production scale experiments should be conducted.

Effect of microoxygenation on acetaldehyde, yeast and colour before and after malolactic fermentation on Pinot Noir wine

“…To date, researchers have identified several key factors associated with the impact of MOX on various red cultivars, including the timing, oxygen dosage and treatment duration of MOX (Cano‐López et al 2008, Durner et al 2010, González‐del Pozo et al 2010), the addition of preservatives (Tao et al 2007, Gambuti et al 2015), the initial reactive phenolic concentration (Picariello et al 2017), redox equilibria (Arapitsas et al 2012, Vela et al 2018) and microbial influence (Sáenz‐Navajas et al 2018, Ji et al 2020). Few studies, however, have investigated the impact of MOX on Pinot Noir wines (Durner et al 2010, 2015, Schmarr et al 2010).…”

Impact of microoxygenation on Pinot noir wines with different initial phenolic content

“…Values are presented as mean ± standard error (n = 6); DO: dissolved oxygen; ALC%: wine alcohol content; NA, not available. Means within a row followed by different letters are significantly different (Tukey p < 0.05).acetaldehyde in these wines was very limited compared to previous MOX studies where the growth of Saccharomyces cerevisiae was also observed(Sáenz-Navajas et al, 2018;Ji et al, 2020;Yang et al, 2021a). In both Sáenz-Navajas et al(2018), with oxygenation applied at 15 mg/L/month for 48 days, andJi et al (2020), with DO consumption at approximately 0.5 mg/L/day within 49 days, MOX treatments induced an increase of yeast growth to 10 5 CFU/mL towards the end of MOX, which coincided with the increase of acetaldehyde (c. 30-35 mg/L) and the depletion of free SO 2 and DO Yang et al (2021a),.…”

“…Means within a row followed by different letters are significantly different (Tukey p < 0.05).acetaldehyde in these wines was very limited compared to previous MOX studies where the growth of Saccharomyces cerevisiae was also observed(Sáenz-Navajas et al, 2018;Ji et al, 2020;Yang et al, 2021a). In both Sáenz-Navajas et al(2018), with oxygenation applied at 15 mg/L/month for 48 days, andJi et al (2020), with DO consumption at approximately 0.5 mg/L/day within 49 days, MOX treatments induced an increase of yeast growth to 10 5 CFU/mL towards the end of MOX, which coincided with the increase of acetaldehyde (c. 30-35 mg/L) and the depletion of free SO 2 and DO Yang et al (2021a),. applied MOX both before and after MLF (10.8 and 52.4 mg/L/ month for 30 days) and increased acetaldehyde (from around 55 to 120 mg/L, and 35 to 70 mg/L, respectively) at the beginning of treatments, where free SO 2 was not readily detected and DO was still climbing.…”

“…In previous MOX studies, a correlation between acetaldehyde production and the growth of Saccharomyces cerevisiae has been found (Sáenz-Navajas et al, 2018;Ji et al, 2020). It is known that Saccharomyces cerevisiae uses ethanol as a carbon source, when fermentable sugar becomes limited, which produces acetaldehyde (Galdieri et al, 2010;Pozo-Bayón and Moreno-Arribas, 2011).…”

“…These improvements include wine colour stabilisation, softening of astringency, and reducing vegetal characteristics (Cejudo-Bastante et al, 2012;Schmidtke et al, 2011). Several factors affecting the influence of MOX on red table wines have been demonstrated, such as the timing and duration of MOX, the addition of preservatives, oxygen dosage, and microbial influence (Anli and Cavuldak, 2012;Ji et al, 2020). However, very limited information is available for wines made from Pinot noir (Durner et al, 2010;Durner et al, 2015;Yang et al, 2021a;Yang et al, 2021b).…”