How long should ground coffee and vanilla stay in alcohol before the infusion turns bitter?

Expanded Explanation

Ground coffee extracts quickly in alcohol, much faster than many people expect, which is why a relatively short infusion is important. In this recipe, the sweet spot is usually around 12 to 16 hours at room temperature, with 18 hours already pushing into risk territory. Vanilla is more forgiving, but coffee is not. Once the grounds sit too long, woody bitterness, stale roast notes, and drying harshness can start to dominate.

Tasting partway through the infusion is the best safeguard. A good checkpoint is around 10 to 12 hours, then again a few hours later if the coffee still feels soft. The moment the aroma is expressive and the palate tastes roasted but not aggressive, strain it. Waiting for maximum strength often backfires, especially because cocoa and milk-washing do not fully hide overextraction.

One common mistake is assuming the milk-wash will fix a bitter base. It can soften edges, but it cannot completely remove harsh extraction faults. Another mistake is using too fine a grind, which speeds up extraction dramatically and throws more sediment into the mixture. Medium-coarse coffee and disciplined straining time are far more important here than trying to push for extra intensity.