Wort Nitrogen and Yeast Strain Drive Thiol Release, Flavor Expression, and Fermentation Performance in Beer
Why this work is in the frame
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Bibliographic record
Abstract
Polyfunctional thiols (PFTs) contribute potent tropical and fruity aromas to beer at ng/L levels, but their release from cysteinylated and glutathionylated precursors depends on yeast activity and fermentation conditions. This study examined the effects of yeast strain and wort free amino nitrogen (FAN) on thiol biotransformation, fermentation performance, and sensory expression using beers brewed at pilot scale with Cascade hops across three FAN levels (110, 240, 360 mg/L) and five yeast strains, including an IRC7-knockout strain. Low wort FAN significantly enhanced thiol release (up to 3× more 3SH and 4MSP), yet wort prepared with medium or high FAN resulted in greater tropical aroma intensity and was associated with elevated esters. Sensory profiles varied with FAN and yeast strain, revealing off-flavors (diacetyl & sulfur/egg) at FAN extremes. The IRC7-knockout strain surprisingly maintained thiol production similar to its parent, suggesting alternative enzymatic pathways for thiol release. These findings highlight FAN’s role in modulating volatile profiles and fermentation kinetics, offering practical strategies to optimize hop aroma and flavor balance in beer.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 it