Method 2: The Hot Amylex Two-Step (Gusmer/LH)
Working notes from real 2018 sessions, not a validated homebrew protocol — values are starting points, and the scale-translation warnings apply to all four methods.
Where this comes from: 2018 Robobrew session notes
This is one of four mash methods Bard's documented in 2018 while adapting its production process to homebrew scale, run on a Robobrew — a recirculating single-vessel electric system (why that equipment class matters).
Corrected 2026-08-09: 181°F is strike water, not a rest temperature
An earlier version of this page presented this as a single rest held at 180°F — taken from a compressed summary block in the source document. Craig, who ran these sessions, flagged it: 181°F (82.75°C) is the strike-water temperature. Once the grain goes in, the mash sits at about 167°F (75°C), and there is a second, cooler conversion rest the summary omitted. The run sheet below follows the full written-out process in the same document. (This box originally repeated the summary's 180°F while giving 82.75°C beside it — 82.75°C rounds to 181°F, matching the run sheet; aligned 2026-08-23.)
The supplier's process, in one breath
As the supplier described it: mash in at 75°C with the Amylex (heat-stable alpha-amylase) and hold 60 minutes; add cold water to drop to 65°C, add the Diazyme (glucoamylase), and hold 45 minutes; mash out at 75°C and transfer. Everything below is that process with Bard's homebrew-scale numbers.
Sorghum starch gelatinizes across 154–178°F (68–81°C). With grain in, this mash lands near 167°F — inside that band but well below the top of it, so the higher-gelatinizing fraction of the starch never opens. That is unconverted extract, and holding longer will not recover it.
The enzyme is not the constraint. This method liquefies with an Amylex-class heat-stable alpha-amylase, and the glucoamylase is deliberately held back until the mash cools to 149°F. The heat-stable enzyme is the one doing the hot work, and it is rated well above 167°F — The Reliable Mash runs the same class of enzyme at 190°F for exactly this reason.
Value left as documented. This is the enzyme supplier's own process as Bard's recorded it in 2018. We do not adjust a third party's method and keep their name on it — if the temperature were raised, this would no longer be their process. Read it as documented practice with a known ceiling on starch access. See Gelatinization.
Hot Amylex Two-Step (Gusmer/LH), Homebrew Scale
- Protocol
- GFB-HB2
- Version
- 2018 notes
- Effective
- August 2026
The enzyme supplier's process adapted to homebrew: strike hot so the mash lands at 167°F with grain, liquefy with a heat-stable alpha-amylase at a deliberately high pH, then cool to 149°F for a glucoamylase finish. The one method of the four that runs two vessels — a mash tun with the Robobrew as hot-liquor tank and HERMS heat source. Batch basis: 10 lb sorghum malt + 1 lb roasted sorghum malt.
Critical: 181°F (82.75°C) is the strike-water temperature, not a rest — with grain in, the mash sits at about 167°F (75°C). And this method moves pH up before it comes down: sodium hydroxide to pH 6+ for the hot rest, then phosphoric to 5.2 for conversion. Sodium hydroxide is caustic — go slowly and keep notes.
Stage before grain-in
Treat and heat
- Do
- Adjust the water with mineral salts, then heat it in the Robobrew to 181°F.
- Add
- Mineral salts
- Advance when
- Water at 181°F.
- Record
- Salt additions · Strike temperature
Grain into the mash tun
- Do
- Load the mash tun: 10 lb sorghum malt, 1 lb roasted sorghum malt, 1 lb rice hulls.
- Add
- 10 lb sorghum malt
- 1 lb roasted sorghum malt
- 1 lb rice hulls
- Advance when
- Grist loaded and mixed.
- Record
- Grain bill and lots
Hot water onto the grain
- Do
- Add 3.75 gallons of the 181°F water (1.25 L/kg). Check the mash temperature — it should read about 167°F with grain in.
- Add
- 3.75 gal water at 181°F (1.25 L/kg)
- Advance when
- Mash at ~167°F.
- Record
- Actual mash temperature with grain
Raise pH for the hot enzyme
- Do
- Raise mash pH to 6.0 or better with sodium hydroxide, slowly, keeping notes on how much.
- Add
- Sodium hydroxide to pH 6+
- Advance when
- pH at or above 6.0.
- Record
- NaOH amount · pH reading and temperature
The hot Amylex rest
- Do
- Add 7 g Amylex. Stir at least every 20 minutes and recirculate to homogenize the temperature.
- Add
- 7 g Amylex-class heat-stable alpha-amylase
- Advance when
- The 60-minute rest is complete.
- Record
- Stir/recirculation events · Temperature stability
Set up the conversion
- Do
- Slowly add about 2 gallons of cold water to reach 149°F. Drop pH to 5.2 with phosphoric acid. Set the Robobrew toward mash-out temperature and its water below pH 6.0 for the coming sparge.
- Add
- ~2 gal cold water
- Phosphoric acid to pH 5.2
- Advance when
- Mash at 149°F and pH 5.2.
- Record
- Water added · Acid amount · Final pH
The glucoamylase finish
- Do
- Add 30 g Diazyme SSF. Stir every 20 minutes. Check for full conversion at the end.
- Add
- 30 g Diazyme-class glucoamylase
- Advance when
- Conversion checks complete.
- Record
- Conversion check result
HERMS ramp to mash-out
- Do
- Recirculate through the HERMS coil until the mash reaches 167°F and runs clear.
- Add
- None
- Advance when
- At temperature, running clear.
- Record
- Time to temperature
Collect 7.75 gallons
- Do
- Transfer to the boil kettle, sparge with about 3 gallons, and collect 7.75 gallons total.
- Add
- ~3 gal sparge water
- Advance when
- Volume and gravity at target.
- Record
- Volume collected · Gravity vs 15.0°P
| Step | Action | Target | Add | Advance when |
|---|---|---|---|---|
| 1. Water: more detail | Adjust the water with mineral salts, then heat it in the Robobrew to 181°F. | 181°F (82.75°C) — |
| Water at 181°F. |
| 2. Load: more detail | Load the mash tun: 10 lb sorghum malt, 1 lb roasted sorghum malt, 1 lb rice hulls. | — — |
| Grist loaded and mixed. |
| 3. Mash in: more detail | Add 3.75 gallons of the 181°F water (1.25 L/kg). Check the mash temperature — it should read about 167°F with grain in. | 167°F (75°C) with grain — |
| Mash at ~167°F. |
| 4. pH up: more detail | Raise mash pH to 6.0 or better with sodium hydroxide, slowly, keeping notes on how much. | pH 6.0 or better — |
| pH at or above 6.0. |
| 5. Liquefy: more detail | Add 7 g Amylex. Stir at least every 20 minutes and recirculate to homogenize the temperature. | 167°F (75°C) 60 min |
| The 60-minute rest is complete. |
| 6. Cool + pH down: more detail | Slowly add about 2 gallons of cold water to reach 149°F. Drop pH to 5.2 with phosphoric acid. Set the Robobrew toward mash-out temperature and its water below pH 6.0 for the coming sparge. | 149°F (65°C), pH 5.2 — |
| Mash at 149°F and pH 5.2. |
| 7. Convert: more detail | Add 30 g Diazyme SSF. Stir every 20 minutes. Check for full conversion at the end. | 149°F (65°C) 45 min |
| Conversion checks complete. |
| 8. Mash out: more detail | Recirculate through the HERMS coil until the mash reaches 167°F and runs clear. | 167°F (75°C) Until clear | None | At temperature, running clear. |
| 9. Run off: more detail | Transfer to the boil kettle, sparge with about 3 gallons, and collect 7.75 gallons total. | 15.0°P (1.061) — |
| Volume and gravity at target. |
Run each step with its checks and context
Use the run sheet during a routine mash. Use these expanded steps when setting up the process, training an operator, documenting a deviation, or diagnosing unexpected behavior.
Treat and heat
Objective
Brewing water adjusted and hot enough that the mash lands at rest temperature with grain.
Operating instruction
Adjust the water with mineral salts, then heat it in the Robobrew to 181°F.
- Mineral salts
What good looks like
Water at 181°F.
Watch for
No additional step-specific warning.
Record
Salt additions · Strike temperature
Grain into the mash tun
Objective
The bed built dry, hulls included, before the hot water meets it.
Operating instruction
Load the mash tun: 10 lb sorghum malt, 1 lb roasted sorghum malt, 1 lb rice hulls.
- 10 lb sorghum malt
- 1 lb roasted sorghum malt
- 1 lb rice hulls
What good looks like
Grist loaded and mixed.
Watch for
No additional step-specific warning.
Record
Grain bill and lots
Hot water onto the grain
Objective
Mash lands at liquefaction temperature — the strike heat minus the grain.
Operating instruction
Add 3.75 gallons of the 181°F water (1.25 L/kg). Check the mash temperature — it should read about 167°F with grain in.
- 3.75 gal water at 181°F (1.25 L/kg)
What good looks like
Mash at ~167°F.
Watch for
No additional step-specific warning.
Record
Actual mash temperature with grain
Raise pH for the hot enzyme
Objective
The heat-stable alpha performs best near pH 6.5 and tolerates the heat — give it its chemistry.
Operating instruction
Raise mash pH to 6.0 or better with sodium hydroxide, slowly, keeping notes on how much.
- Sodium hydroxide to pH 6+
What good looks like
pH at or above 6.0.
Watch for
Overshooting — sodium hydroxide moves pH fast.
If this happens
Add in small increments; a cooled sample or temperature-compensated meter keeps the reading honest.
Record
NaOH amount · pH reading and temperature
The hot Amylex rest
Objective
Heat-stable alpha-amylase liquefies at a temperature where sorghum starch is gelatinizing fast.
Operating instruction
Add 7 g Amylex. Stir at least every 20 minutes and recirculate to homogenize the temperature.
- 7 g Amylex-class heat-stable alpha-amylase
What good looks like
The 60-minute rest is complete.
Watch for
Temperature loss in an uninsulated tun.
If this happens
Lean on the recirculation loop — it exists for this.
Record
Stir/recirculation events · Temperature stability
Set up the conversion
Objective
Down to glucoamylase territory in temperature and pH at once.
Operating instruction
Slowly add about 2 gallons of cold water to reach 149°F. Drop pH to 5.2 with phosphoric acid. Set the Robobrew toward mash-out temperature and its water below pH 6.0 for the coming sparge.
- ~2 gal cold water
- Phosphoric acid to pH 5.2
What good looks like
Mash at 149°F and pH 5.2.
Watch for
No additional step-specific warning.
Record
Water added · Acid amount · Final pH
The glucoamylase finish
Objective
Drive fermentability — the glucose-forward route, like the modern production process.
Operating instruction
Add 30 g Diazyme SSF. Stir every 20 minutes. Check for full conversion at the end.
- 30 g Diazyme-class glucoamylase
What good looks like
Conversion checks complete.
Watch for
No additional step-specific warning.
Record
Conversion check result
HERMS ramp to mash-out
Objective
Bed to 167°F and running clear before transfer.
Operating instruction
Recirculate through the HERMS coil until the mash reaches 167°F and runs clear.
What good looks like
At temperature, running clear.
Watch for
No additional step-specific warning.
Record
Time to temperature
Collect 7.75 gallons
Objective
Wort to the kettle at target volume.
Operating instruction
Transfer to the boil kettle, sparge with about 3 gallons, and collect 7.75 gallons total.
- ~3 gal sparge water
What good looks like
Volume and gravity at target.
Watch for
No additional step-specific warning.
Record
Volume collected · Gravity vs 15.0°P
What makes this one different
pH goes up before it comes down. Every other method on this site acidifies. This one raises the mash to pH 6+ with sodium hydroxide because the hot-side enzyme performs best near 6.5, then drops to 5.2 for the glucoamylase. Two pH moves, each serving the enzyme that's working at the time.
A glucoamylase finishes it. The 149°F rest with Diazyme drives fermentability the way the Sugar Bible describes — glucose-forward, like the current production process.
Two vessels. Mash tun plus Robobrew-as-HERMS. More plumbing, but the recirculating mash-out and controlled sparge are the payoff.
An earlier iteration exists. The same document's summary block sketches a variant: split grain addition (half in, enzyme, then the rest), calcium hydroxide to pH 5.75, Amylex BT2, conversion judged by iodine. Same family, earlier pass — the full write-up above supersedes it.
Watch for
Sodium hydroxide is caustic and easy to overshoot — go slowly and keep notes; pH measurement in a hot mash (cool the sample or use a temperature-compensated meter); and temperature loss in the uninsulated mash tun during the 60-minute rest — the recirculation loop is there for a reason.
Report back
Nobody has published results for this method at homebrew scale — which means your batch is data. Report efficiency, mash behavior, runoff, gravity against the 15.0°P target, fermentation, and what you'd change. See Research Ask #3 and tell us what happened.
Related
- Mash Methods at Homebrew Scale
- The Sugar Bible — why the glucoamylase rest changes the wort
- Water, Minerals, and pH