Toward umami retention in low-alcohol lager beer: discovery and mechanistic validation of umami peptides

Alcohol reduction in lager beer can weaken body and umami richness. Here, 2120 polypeptides were identified in low-alcohol lager beer by RPLC-QTOF-MS with stringent confidence filtering. An integrated pipeline combining machine learning (threshold 0.95) and molecular docking screened 61 candidate umami peptides. Docked candidates were mainly short peptides (≤6 residues, 74.6%) enriched in acidic sites (D/E, 67.2%). In the T1R1/T1R3 VFT model, candidates were predicted to anchor via terminal salt bridges and hydrogen-bond networks, while van der Waals interactions dominated (mean proportion 0.661); for nine representative peptides, MM-GBSA ΔGbind ranged from −79.53 to −29.02 kcal/mol. Sensory testing in the beer matrix indicated that 8 of 9 peptides increased umami scores, with a mean increase of 15.2%. Based on concordance between predicted interactions and sensory responses, STEWHL, KNTET, EVEKR, EEY, EEDW, and EHE were prioritized as novel umami peptide candidates for low-alcohol lager beer. Because effects were evaluated under controlled addition and focused on umami, broader impacts on overall flavor balance and potential trade-offs should be assessed in future work.