Research note: The influence of micro-oxygenation on the long-term ageing ability of Pinot noir wine

In this study, Pinot noir wines were bottle aged for 12 and 18 months after micro-oxygenation (MOX) applied before or after malolactic fermentation (MLF) at two doses (10.8 and 52.4 mg/L/month). After ageing, a greater decrease in the total SO₂ concentration was found in wines with the higher MOX dosage, demonstrating a long-term impact of higher oxygen exposure on wines’ SO₂ requirement. Meanwhile, a negative impact of MOX on wine colour development occurred over time, resulting in a large loss of colour measures (i.e., 420 nm for brown hues, 520 nm for red colour, SO₂ resistant pigments, and colour intensity), which was greater with the early oxygen exposure. This was linked to a significantly lower content of large polymeric pigments in MOX treatments. Tannin concentration was, in the end, not affected by the MOX treatments. However, regarding tannin composition, considerably higher (-)-epicatechin extension units but much lower (-)-epicatechin terminal units were found with MOX treatments. In addition, a significant reduction of tannin trihydroxylation (%Tri-OH) but a higher galloylation (%Galloyl) and mean degree of tannin polymerisation (mDP) remained in wines with MOX, indicating a long-term negative influence on astringency intensity

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

Microoxygenation (MOX) is used to improve wine colour and sensory quality; however, limited information is available for Pinot noir wines and wines with different initial phenolic content. In this study, MOX was applied to two Pinot noir wines, with either a low or a high phenolic content, at two doses (0.50 and 2.11 mg/L/day) for 14 days. With the sterile filtration applied, acetaldehyde formation during MOX was very low, supporting the influence of yeast on acetaldehyde production during MOX. The MOX dosage rate did not significantly affect colour development, while the Pinot noir wine with higher phenolics benefited more from MOX, significantly increasing colour intensity and SO₂ resistant (polymeric) pigments. However, these changes did not guarantee colour stability, as a final SO₂ addition (100 mg/L) largely erased the improvement to colour in all wines. This could be due to the lower acetaldehyde formation, thus less ethyl-bridged stable pigments resistant to SO₂ bleaching. MOX also decreased the flavan-3-ols and anthocyanin monomers, which differed between the two Pinot noir wines, reflecting the initial phenolic content. Lastly, MOX generally increased the measured tannin concentration and affected the proportion of tannin subunits, with a decrease in tannin mass conversion and proportion of (-)-epigallocatechin extension units. Some of these changes in phenolic compounds could potentially increase astringency, suggesting that MOX should be applied to Pinot noir and other low phenolic wines with caution

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

Background and Aims: Microoxygenation (MOX) is widely used in winemaking. Its impact, however, on Pinot Noir wines has not been well documented. We investigated the influence of MOX on colour parameters and on the anthocyanin and polymeric pigment concentration of a young Pinot Noir wine. The relationship between MOX, yeast growth and acetaldehyde production was also explored. Methods and Results: Microoxygenation was applied before or after malolactic fermentation (MLF), and at two oxygen doses [10.8 and 52.4 mg/(L ·month)], for 30 days. The end result was reported after dissolved oxygen was depleted and 90 mg/LSO₂ was added. Microoxygenation induced a higher yeast growth and acetaldehyde production, where the latter was associated with both yeast metabolism and chemical oxidation. A larger loss in total anthocyanins and malvidin-3-glucoside occurred under MOX but absorbance at 520 nm and colour intensity were higher. With the higher oxygen dose, MOX promoted the formation of large polymeric pigments. Conclusions: Acetaldehyde formation was strongly induced by MOX, contributing to reactions between anthocyanins and acetaldehyde forming pigments in the red spectrum. Between MOX treatments, only slight variation was found for each parameter, indicating a less important effect of the timing and dosage of MOX on the young Pinot Noir wine than anticipated from prior work. Significance of the Study: Microoxygenation caused a significant impact on the colour development of light-coloured Pinot Noir wine, increasing the colour intensity

Effect of microoxygenation applied before and after malolactic fermentation on monomeric phenolics and tannin composition of Pinot Noir wine

Background and Aims: This study examines the effect of microoxygenation (MOX) applied before and after malolactic fermentation (MLF) on monomeric phenolic compounds and the tannin composition of a young Pinot Noir wine. It provides a complementary study to an earlier report on the effect of MOX on Pinot Noir colour and pigment development. Methods and Results: Two oxygen doses [10.8 and 52.4 mg O₂/(L month)] were applied either before or after MLF for 30 days. The wines were analysed by a series of HPLC-based methods for phenolic compounds, with sources including both the Pinot Noir grape and a minor contribution from commercial tannin and oak additives. Post-MLF MOX led to the near complete hydrolysis of cis-and trans-coutaric acids and to the conversion of trans-caftaric acid to caffeic acid, which has been associated with MLF. An increase of syringic acid was also found with post-MLF MOX. For tannin composition, MOX decreased the proportion of trihydroxylation (%Tri-OH) but increased galloylation (%Galloyl). Between MOX treatments, the effect of MOX dosage was much stronger than MOX timing on phenolic measures. Conclusions: Post-MLF MOX greatly affected the enzymatic hydrolysis of hydroxycinnamic acids. With MOX, the decrease in %Tri-OH and the increase in %Galloyl could increase astringency perception. The higher oxygen dosage had a greater impact on tannin composition than shown previously with colour-related parameters. Significance of the Study: The influence of MOX on Pinot Noir phenolic composition has not been reported previously in such detail. Applying MOX to a young Pinot Noir wine altered the phenolic units responsible for astringency

The Kava Anxiety Depression Spectrum Study (KADSS): A randomized, placebo-controlled crossover trial using an aqueous extract of Piper methysticum

Rationale: Piper methysticum (Kava) has been withdrawn in European, British, and Canadian markets due to concerns over hepatotoxic reactions. The WHO recently recommended research into “aqueous” extracts of Kava. Objective: The objective of this study was to conduct the first documented human clinical trial assessing the anxiolytic and antidepressant efficacy of an aqueous extract of Kava. Design and participants: The Kava Anxiety Depression Spectrum Study was a 3-week placebo-controlled, double-blind crossover trial that recruited 60 adult participants with 1 month or more of elevated generalized anxiety. Five Kava tablets per day were prescribed containing 250 mg of kavalactones/day. Results: The aqueous extract of Kava reduced participants' Hamilton Anxiety Scale score in the first controlled phase by −9.9 (CI = 7.1, 12.7) vs. −0.8 (CI = −2.7, 4.3) for placebo and in the second controlled phase by −10.3 (CI = 5.8, 14.7) vs. +3.3 (CI = −6.8, 0.2). The pooled effect of Kava vs. placebo across phases was highly significant (p < 0.0001), with a substantial effect size (d = 2.24, η² [sub]p[sub] = 0.428). Pooled analyses also revealed highly significant relative reductions in Beck Anxiety Inventory and Montgomery–Asberg Depression Rating Scale scores. The aqueous extract was found to be safe, with no serious adverse effects and no clinical hepatotoxicity. Conclusions: The aqueous Kava preparation produced significant anxiolytic and antidepressant activity and raised no safety concerns at the dose and duration studied. Kava appears equally effective in cases where anxiety is accompanied by depression. This should encourage further study and consideration of globally reintroducing aqueous rootstock extracts of Kava for the management of anxiety