Mousiness

Lactic acid bacteria (Lactobacillus, Pediococcus) and some Brettanomyces strains produce compounds (2-acetyl-1-pyrroline, 2-ethyltetrahydropyridine) that cause a mouse-cage-like aftertaste. Particularly associated with low-SO2 and natural wines.

Not detected on the nose — only perceived as a lingering, unpleasant aftertaste described as mouse cage, cereal, or crackers. Rub a drop on the back of your hand and smell after it dries to lower the pH and make the compounds volatile. The retronasal perception is distinctive and persistent.

Adequate SO2 management (the compounds are only produced in low-SO2 environments), maintaining low pH, proper cellar hygiene, and controlling LAB populations. No cure once present. One of the most debated faults in the natural wine community.