Brut IPA (II: The Enzyme)

The first part of this article describes brut IPA and discusses the grist and the mash.

Moonshiners like it, too.

A step mash can yield a highly fermentable wort that results in a dry to very dry beer. However, if you wish to go beyond “ordinary dryness” — as the pioneers of brut IPA do — you need something extra. That thing is an exogenous enzyme (i.e. an enzyme you add) that will degrade the “dextrins” in your wort to a degree beyond that accomplished in any mash. For the brewers of brut IPA, the enzyme of choice is amyloglucosidase.

Amyloglucosidase

Commercial brewers of brut IPA use amyloglucosidase to dry out their beer. (There are similar enzymes that could also do this.) Amyloglucosidase attacks the ends of starch strands, as beta amylase does, and “chops off” one glucose molecule. Beta-amylase, of course, binds in a similar manner, but yields maltose (two glucose residues). For those with a bit of a chemistry background, amyloglucosidase binds preferentially to the non-reducing ends of “long” carbohydrate strands from the “1 to 6” linkages and “1 to 4” linkages in starch. It will also bind to maltose and maltotriose and reduce them to glucose or glucose and maltose. With a sufficient amount of enzyme and time, the starches in your wort can be reduced entirely to simply sugars. 

White Labs sells a product called Ultra Ferm, a liquid that contains amyloglucosidase. They claim that it will convert all the starch into simple sugars, where as normally, only 75–80% of the starch is converted in the mash. This enzyme should be added when the mash (or kettle wort) is at or below 140 °F (60 °C). The pH should be below 5.5. The recommended dosage is 25 mL per 10 bbl (315 gallons/1,190 L), or 0.4 mL per 5.0 gallons (19 L).

Likewise, Brewers Supply Group sells Amlo 300, an amyloglucosidase enzyme in powdered form. The dosage amount for BSG’s powder is 2-7 per hL (100 L), or 0.4–1.4 g per 20 L. These are very small, but not unmeasurably small, amounts at the homebrew scale. Also, small errors in measurement — and especially adding a little too much enzyme — will not have any negative effect.

The enzyme can also be found at websites that cater to distillers and at scientific supply houses.

A space filling model of the enzyme amyloglucosidase. The active site is colored yellow.

Amyloglucosidase can be added to a step mash program, before the temperature exceeds 140 °F (60°C), or it can be added to wort run off into the kettle. Given the tiny amount of enzyme added, it would probably help to have a slightly thinner than usual mash and to stir it well several times if you go that route. If you treat your wort in your kettle, prior to the boil, be sure the temperature is not too high. If you want the driest beer possible, adding the enzyme to kettle wort is the preferred approach. Hold at around 140 °F (60 °C), or slightly less, for about 15 minutes, then proceed towards the boil. The boil will denature the enzyme and stop any further action, if any “dextrins” are left at this point. 

In the next installment, I’ll discuss hop additions in the boil. Later articles will discuss fermentation and packaging.

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Comments

  1. Quite interesting! It’s good to read a little bit about biochemistry as it is more or less all in brewing! Could you please confirm that after addition of the amyloglucosidase, it’s just take 15 min at 60°C to convert the long sugars into small ones for 5 gallons of “classic” wort? It’s really efficient! Also, do the apparent attenuation of the yeast will be higher in that case compare to a wort without addition of the amyloglucosidase, due to the specific sugar profile of the wort?
    Best regards,
    Yan (From France)

  2. On the package for White Labs WLN4100 Ultra Ferm it says it’s good up to 185 degrees. Stats dosage as 10ml per 5 gallons

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