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Method 2: The Hot Amylex Two-Step (Gusmer/LH)

The enzyme supplier's process, adapted to homebrew: strike hot so the mash lands at 167°F, liquefy with a heat-stable alpha-amylase at a deliberately high pH, then cool to 149°F and let a glucoamylase finish the conversion. Two rests, two pH moves, and the only method of the four that adjusts pH up first.
Where this comes from

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). These are working notes from real sessions, not a validated homebrew protocol. Values are starting points; the scale-translation warnings apply to all four.

Corrected 2026-08-09

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: 180°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.

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.

The run sheet​

This adaptation runs the grain in a separate mash tun with the Robobrew as hot-liquor tank and HERMS heat source — the one method of the four that uses two vessels.

#StepTargetTimeAdditions
1Adjust brewing water——Mineral salts
2Heat strike water in the Robobrew181°F (82.75°C)——
3Load the mash tun——10 lb sorghum malt + 1 lb roasted sorghum malt + 1 lb rice hulls
4Mash inMash lands at 167°F (75°C) with grain—3.75 gal of the hot water (1.25 L/kg)
5Raise pH——Sodium hydroxide to pH 6.0 or better — the enzyme wants pH ~6.5 and tolerates up to 185°F. Keep notes on how much
6Liquefaction rest167°F60 min7 g Amylex; stir at least every 20 min; recirculate to homogenize temperature
7Cool149°F (65°C)—~2 gal cold water, added slowly
8Drop pH——Phosphoric acid to pH 5.2 — the glucoamylase's range. Set the Robobrew water below pH 6.0 for the coming sparge
9Conversion rest149°F45 min30 g Diazyme SSF; stir every 20 min; check for full conversion
10Mash out167°F (75°C)—Recirculate through the HERMS coil (Robobrew set to 194°F) until at temperature and running clear
11Run off——Transfer, sparge with ~3 gal, collect 7.75 gal total to the boil

Target extract: 15.0°P (1.061).

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.