Enzymes

We know that the two enzymes critical for brewing are α- and β-amylase. The malting process affects the levels of these enzymes. If you are not sure how, now take a look back at the malting process lesson.

Dextrinising units (DU)

α-Amylase activity is expressed as dextrinising units (DU). α-Amylase catalyses the random hydrolysis (breakdown) of starch to produce shorter glucose chains (dextrins) and sugars. The mashing biochemistry lesson covers enzyme function in more detail. To measure α-amylase activity, we measure the time it takes a solution of the enzymes from the malt to break down a starch solution in the presence of an excess of β-amylase. The rate of breakdown is established by timing how long it takes to  produce a specific colour change using iodine as an indicator (iodine stains starch black/blue). 30-50 DU is adequate for malt used in an all-malt mash, with higher values required if you are using other adjuncts in the mash.

Diastatic power (DP)

DP represents the capacity of the enzymes in the malt to break down starch. It is a measure of the combined activity of α and β-amylase. The malt enzymes are extracted in to an aqueous buffer solution and this is added to a standard solution of starch. The amount of reducing sugars produced by the starch breakdown is estimated by titration with iodine and thiosulphate. A method using automated discrete analysis on a Gallery Beermaster is also available and approved by the EBC. The link below provides more information on the Gallery Beermaster

Note, this is for illustrative purposes only and is not a recommendation or endorsement of the supplier’s product:

https://www.thermofisher.com/uk/en/home/industrial/chromatography/automated-wet-chemical-analysis/discrete-analysis-products/gallery-plus-beermaster-discrete-analyzer.html

The units of DP are:

  • Degrees Windisch Kolbach (˚WK) (EBC)
  • Degrees Lintner (˚L) (ASBC)
  • Degrees IoB (IoB) (results are very close to the ASBC method)

Typical DP values are as follows:

35-40 ˚L for standard ale malts.

100-125 ˚L for pale malts.

> 160 ˚L for some six-row malts

How do ˚WK and ˚L relate to each other? Here is a formula which allows you to convert one to the other.

begin mathsize 14px style text DP ˚Lintner =  end text fraction numerator left parenthesis ˚ WK space plus space 16 right parenthesis over denominator 3.5 end fraction space end style

˚WK = (3.5 x ˚L) - 16

Enzyme activity is sometimes presented on malt analysis sheets as saccharification time. This is the time taken to convert all of the starch in a standard mash. This is reported in minutes, typically 5-10 min, or 10-15 min. As you would expect, anything longer than 15 min suggests a problem.

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