Dry hopping: when, how much, and for how long
This summer I split one 24-litre batch of pale ale into three fermenters and dry hopped each at a different time. Same wort, same yeast, same hops: 5 grams per litre of a citrusy American variety.
| Fermenter | Dry hop added | Contact time |
|---|---|---|
| A | Day 2, active fermentation | 5 days |
| B | Day 6, fermentation finished | 3 days |
| C | Day 6, fermentation finished | 7 days |
What came out
A was the softest and most tropical. Adding hops while the yeast is still busy means the carbon dioxide scrubs some aroma away, but the yeast also transforms some hop compounds, and the result was rounder than the other two. It also finished two points lower: hops added during fermentation bring enzymes that let the yeast eat a little more sugar.
B had the brightest, most direct hop aroma. Three days at fermentation temperature was plenty. Most of the aroma is extracted within the first day or two.
C was the disappointment: grassy and slightly harsh. Longer is not better; after a few days the vegetal flavours keep coming while the pleasant ones do not.
What I do now
- Split the dry hop: a small charge on day two, the main charge once fermentation is done.
- Keep the main contact to three or four days, then cold crash.
- Purge the fermenter with CO₂ after opening it. Oxygen pickup at this stage ruins a hoppy beer in a couple of weeks.
- Watch the gravity after an early dry hop. Taking the beer off the yeast too soon can mean over-carbonated bottles.