Vicinal Diketone Production and Amino Acid Uptake by Two Active Dry Lager Yeasts during Beer Fermentation
Bibliographic record
Abstract
Amino acid consumption and vicinal diketone (VDK) production of two different strains of commercially available active dry lager yeasts (ADLYs) were compared with freshly propagated cultures of the corresponding yeast strains. Rehydrated dry yeasts and freshly propagated yeasts were pitched in all-malt wort and allowed to ferment at 14°C. Dry yeast strains took 15–26 hr longer to attenuate the wort to final gravity and 24–48 hr longer to significantly reduce wort amino acid content. A new indicator was introduced as a means to quantitatively characterize VDK production and reduction profiles. This indicator effectively demonstrated a large discrepancy in the diacetyl profile between the fresh and dry cultures: fermentations made with dried yeasts resulted in 1.5–7 times higher diacetyl indices. With one of the dry strains, diacetyl concentrations remained over the taste threshold value after 7 days of fermentation. These differences could be linked to a reduced ability of the rehydrated mother cells to absorb wort constituents caused by cell membrane damage occurring during the ADLY production process. Overall, dry yeasts resulted in a reduced level of performance compared with freshly propagated cultures, suggesting that the direct utilization of ADLY as an inoculum for beer fermentation at the industrial scale is not recommended.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".