Experiments

Experiment: Dry Hop Timing and Yeast-determined Haze

See the differences in haze and clarity when dry hop timing varies with a haze-positive and haze-neutral yeast strain.

By Danielle Sommer

May 15, 2024

Yeast-driven Haze

Lab trials turned up an important factor in haze for Omega Yeast’s researchers: yeast-driven haze. See the stark differences in haze outcomes when dry hop timing varied with what Omega Yeast researchers coined as haze-positive” strains and haze-neutral” strains. Yeast makes haze in conjunction with elements of the dry hop, and some strains are better at it than others.

The Experiment

For each series in this experiment, researchers inoculated nine identical flasks of wort with the same yeast on the same day, and then dry hopped them at different times during fermentation (note: the control flask — pictured above — was not dry hopped. The central flasks were dry hopped on progressive days — day zero, one, two, three, four and seven. The last flask was double dry-hopped, and received half early in fermentation and half late).

Test Yourself

Can you identify which series in the image above was fermented with British V (haze-positive) and which with Chico aka West Coast Ale I (haze-neutral).

TIP: look for substantial haze with later dry hop timing to find the haze-positive strain. Keep scrolling for the solution (below)!

Omega Yeast tested strains in their catalog for haze potential and divided them into high and low:

Haze-positiveHaze-neutral
British Ale IBayern Lager
British Ale VBritish Ale VIII
East Coast AleDaybreak V
Hefeweizen Ale IDIPA (Conan)
Irish AleFrench Saison
Kolsch IGerman Lager I
Kolsch IILutra Kveik
*Point Loma (W Coast Ale III)Point Loma +
Scottish AleTropical IPA
Voss KveikW Coast I (Chico)
West Coast Ale II

DID YOU GET IT RIGHT?

Dry hop timing 01

Haze-positive

With British V haze levels increased when the dry hop happened later during fermentation.

Dry hop timing 02

Haze-neutral

With West Coast Ale I haze levels are too low to establish a haze styling from a yeast-determined source, no matter when the dry hop happens.

Double dry hop flask experiments

Day of fermentation dry hop: control (none), KO” (essentially at yeast pitch), day 4, day 7, and days 1&7 (double dry hopped).

BONUS

Flasks that received both an early- and a late-fermentation dry hop (“1 & 7”)consistently dropped clear. This was like how the early-fermentation dry hop alone behaved. That means the early-fermentation dry hop has a dominant clarifying effect. That phenomenon could be useful for brewers who want clarity instead of haze.

It’s hard to tell in the pictures of the flask series up above. At the time those photograph were taken the flasks were still somewhat active with yeast in suspension. This photo from an additional experiment shows the phenomenon much more clearly.


SUMMARY

If you understand yeast-contributed haze in relation to dry hop timing, and how it differs with haze-positive and haze-neutral strains, hopefully it was pretty easy to spot which was which: 

Haze-positive strains can contribute significant levels of haze in beer in conjunction with mid-to-late fermentation dry hop timing (and can drop clear with early-fermentation dry hop timing), thanks to something going on with their version of the HZY1 gene.

Haze-neutral strains don’t ever achieve significant levels of yeast-driven haze. 

And, an early- and late-fermentation double dry hop behaves like early-fermentation dry hop in terms of haze. The early-fermentation dry hop dominates even with later-fermentation dry hopping.

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