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The Maltose Mash at Homebrew Scale

This is the research brew. The mash we would brew, translated to 5 gallons (18.9 L): a protease rest, a hot liquefaction, then a cool fungal-alpha conversion that targets a maltose-forward wort instead of the Reliable Mash's glucose-heavy one. Its chemistry made most of the beer Bard's ever sold. Nobody has measured a brewhouse run of this sheet, at any scale, and a homebrewer with a notebook is exactly who could.

The Maltose Mash owns the controlling values and the argument for them. This page answers the question that page can't: what does it look like in a 10-gallon kettle, and where does the day go wrong?

Watch on YouTubeThe Maltose MashThe design in full: what it targets, what it rests on, and what it has never had. AI-generated from the production page and reviewed for accuracy.7:09

The batch this assumes​

A 5-gallon batch from 10 lb (4.5 kg) sorghum malt, the same grist as the Reliable Mash at homebrew scale, so the two can be run as the split batch Research Ask 4 is waiting for. Every dose is per pound; scale the table to your grain bill.

The numbers, translated​

StageTargetTimeAdditions for 10 lb malt
Mash in, protease rest122°F (50°C), pH 6.030 min~3.1 gal (11.8 L) strike water at 2.6 L/kg with CaCl₂ to ~100 ppm; 10 mL Termamyl SC DS and 2.5 mL Neutrase 0.8L in the water before the grain; malt in slowly, stirring
Thinning rest155°F (68°C)20 minramp; nothing added
Liquefy190°F (88°C)45 minramp at about 1°F per minute; nothing added
Convert132°F (56°C), pH 5.5100 mincool with ~7.3 lb (3.3 kg) of ice (or ~2.9 gal / 11 L of 60°F tap water; see below); 2.25 mL Fungamyl 800L + 7.5 mL Termamyl SC DS
Mash out180°F (82°C)10 min~0.2 lb (0.09 kg) rice hulls at 2%, "if needed", mixed 5–10 min before transfer

Dose basis, from the V12 sheet: Termamyl 1 mL/lb at mash-in and 0.75 mL/lb at conversion; Neutrase 0.25 mL/lb; Fungamyl 0.225 mL/lb; rice hulls 2% of malt weight. The 100-minute hold is the production page's ruling, where the run sheet says 45 and two other documents say 100. The 45-minute liquefaction is V12's own figure and the page keeps it deliberately; if your system holds 190°F badly, the 60-minute baseline is the safer number and the record should say which you ran.

The cool-down is the brew day​

Every other method on this site cools from 190°F (88°C) to 145°F (63°C) or higher. This one drops to 132°F (56°C), and at 2.6 L/kg that is roughly 405 kJ per kilogram of grain to remove. What you cool with decides how thin the mash ends up, and the 132°F hold is where the fungal alpha does the work the whole design exists for, so thinness there is a real cost.

CoolantPer kg of grainFor 10 lbMash after cooling
Tap water, 60°F (16°C)2.42 L~2.9 gal (11 L)5.0 L/kg, nearly double
Cold liquor, 45°F (7°C)2.00 L~2.4 gal (9.1 L)4.6 L/kg
Ice, 32°F (0°C)0.72 kg~7.3 lb (3.3 kg)3.3 L/kg

Ice is the homebrew answer. Melting absorbs heat before the meltwater warms at all, which is why a kilogram of ice does the work of about three and a half litres of tap water. Freeze it from brewing water the day before, weigh it, and add it in stages with the mash moving; then top up with cold water until the grist reads 132°F, and write down the total.

Where those figures come from, and what they leave out

The production page computes the heat balance for a 2.6 L/kg mash from 190°F to 132°F: about 405 kJ per kilogram of grain to remove, which works out to 2.42 L of 60°F tap water or 0.72 kg of ice per kilogram of grain. Ice does more per kilogram because melting absorbs heat before the meltwater warms at all. The figures assume no heat loss to the kettle or the air, which at homebrew scale is not true; a 10-gallon kettle sheds heat fast, so you will need somewhat less coolant than the table says. Add in stages and let the thermometer decide.

Volumes, so the kettle is not a surprise​

Strike water is 11.8 L. With ice, the mash carries about 15 L of liquor at conversion; with tap water, about 23 L. The grain holds back about a litre per kilogram, the usual planning figure, so expect roughly 2.8 gal (10.5 L) of runoff on the ice route and 4.8 gal (18 L) on the tap-water route before any sparge. A 60-minute homebrew boil for 5 gallons typically wants around 6.5 gal (24.5 L) in the kettle, so plan a sparge of about 3.5 gal (13 L) at 180°F (82°C) on the ice route, or 1.5 gal (6 L) on the tap-water route, and record which you did. The two routes make different worts, and the sparge volume is part of that.

Scale it to your batch​

The table above assumes 10 lb. Enter your actual grain weight and get every dose, the strike water, the ice, and the hulls scaled, same published rates, your numbers, printable:

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The four things that decide whether this works​

1. Enzymes in the water before the grain. Both the heat-stable alpha-amylase and the protease go into the 122°F (50°C) strike water first, then the malt goes in slowly with the mash moving. The Termamyl is there for the ramp to 190°F later; a 122°F mash-in without it is a thickening problem waiting for the liquefaction step.

2. Ramp at about 1°F a minute to 190°F (88°C). The production correspondence dates that rate to a brewhouse that stalled its agitator on a fast ramp; the story is on the production page. At home the same physics applies with less horsepower. Sorghum starch opens across 154–178°F and thickens as it does, so the slow ramp through that band, stirring, is what keeps the mash a liquid.

3. Get to 132°F (56°C) and pH 5.5 before the fungal alpha goes in. Fungal alpha-amylase is fragile about both heat and pH. Add it into a mash that is still at 140°F and you are dosing a dying enzyme. Check the temperature in three places, adjust pH down (the mash-in ran at 6.0 for the protease), then dose, then start the 100-minute clock.

4. Hold the 100 minutes and hit 180°F (82°C) at mash-out. The hold length is the lever on the wort's sugar profile; a shorter hold is a different wort, and the Sugar Bible says why. The mash-out stops the enzymes where the design wants them stopped.

What breaks at small scale​

  • The cool-down. See above. Guessing it wrecks the ratio; not measuring it wrecks the record.
  • Thermal mass on the 132°F hold. A hundred minutes is a long time for a 10-gallon kettle to sit at one temperature without a heat source that can hold, rather than overshoot, a cool target. A recirculating system with a controller earns its price here; a burner and a thermometer means small, frequent corrections.
  • The protease rest and foam. V12 doses a protease at mash-in. The production page carries an open foam question about it; at homebrew scale, a head that collapses is data, and the 5 IBU hop-extract rule is the production answer.
  • Enzyme sourcing. These are commercial products in litre jugs. Match the class (heat-stable alpha-amylase, a neutral protease, a fungal alpha-amylase) and follow the vendor's dose if you substitute. Record what you used.
  • Runoff. No husk, a thin or a thick mash depending on your coolant, and hulls at only 2% on the sheet. If the bed seals, the stuck-mash page is the place to go, and 5% next time is a fair change to record.

Where it differs from Old Traditional Bard's​

Method 1 is the same lineage from 2018 notebooks, and it is a different sheet: no protease, a 153°F (67°C) rest and a full boil instead of a 155°F (68°C) rest and a 190°F (88°C) liquefaction, and a 0.5 L/kg cold-water figure that the page itself calls a starting point. Its fold on the differences is worth reading before you choose. This page is the V12 sheet translated; that page is the Robobrew session as run.

What we want to know​

This translation is arithmetic on a production sheet that has no recorded result of its own. If you run it, tell us: your coolant and its volume, the mash ratio at conversion, gravity into and out of the fermenter, a fermentation curve, and, if you can get one, a sugar profile. The run that settles the most is the split batch: this mash and the Reliable Mash on the same malt, same day, same yeast. Contradictions are the most useful reports we can get.

Research needed