Fermentis SafBrew HA-18 High Gravity Enzyme Yeast

This is not a normal yeast. HA-18 is a blend of active dry yeast plus glucoamylase enzyme. The enzyme breaks down more complex sugars than regular yeast can, which lets it push attenuation extremely high — often into the 98–102% range. It was built specifically for very big, very dry beers.

Best For

Barleywines, Imperial Stouts, strong ales, and any high-gravity beer where you want it to finish as dry as possible. Also useful for barrel-aged beers or anything where you need to push past normal yeast limits.

Hard Specs

• Attenuation: 98–102% (extremely high due to enzyme)
• Flocculation: Medium
• Temperature Range: 77–95°F (ideal 80–90°F)
• Alcohol Tolerance: Up to 18% ABV
• More tech specs

Flavor & Behavior

Because of the enzyme, this strain can ferment out a huge amount of sugar, leaving the beer very dry. It also produces some phenolic character (light clove/spice notes) since the yeast component is POF+. The high fermentation temperature range means it likes things warmer than most ale yeasts.

In Practice

This is the “nuclear option” for big beers. If you’re making a barleywine or imperial stout and want it bone-dry with high alcohol, HA-18 can do things that normal yeast struggles with. The tradeoff is that it can make some beers taste thin or harsh if the recipe doesn’t have enough malt backbone or if you’re not expecting that level of dryness. Use it when you specifically want extreme attenuation, not as a general-purpose yeast.

Pitching & Rehydration

One 11g sachet is usually enough for a 5 gallon batch, but for very high-gravity worts (1.090+), consider pitching two sachets or making a small starter. Rehydrate in 86–95°F water for 15–30 minutes before pitching. Temperature control still matters — keep it in its happy range for best results.