Degradation of free and sulfur-dioxide-bound acetaldehyde by malolactic lactic acid bacteria in white wine
Bibliographic record
Abstract
AIMS: Acetaldehyde is the major carbonyl compound formed during winemaking and has implications for sensory and colour qualities of wines as well as for the use of the wine preservative SO(2). The current work investigated the degradation of acetaldehyde and SO(2)-bound acetaldehyde by two commercial Oenococcus oeni starters in white wine. METHODS AND RESULTS: Wines were produced by alcoholic fermentation with commercial yeast and adjusted to pH 3.3 and 3.6. While acetaldehyde was degraded rapidly and concurrently with malic acid at both pH values, SO(2)-bound acetaldehyde caused sluggish bacterial growth. Strain differences were small. CONCLUSIONS: Efficient degradation of acetaldehyde can be achieved by commercial starters of O. oeni. According to the results, the degradation of acetaldehyde could not be separated from malolactic conversion by oenococci. While this may be desirable in white winemaking, it may be necessary to delay malolactic fermentation (MLF) in order to allow for colour development in red wines. SO(2)-bound acetaldehyde itself maybe responsible for the sluggish or stuck MLF, and thus bound SO(2) should be considered next to free SO(2) in order to evaluate malolactic fermentability. SIGNIFICANCE AND IMPACT OF THE STUDY: The current study provides new results regarding the metabolism of acetaldehyde and SO(2)-bound acetaldehyde during the MLF in white wine. The information is of significance to the wine industry and may contribute to reducing the concentration of wine preservative SO(2).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".