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This Month's Question:  What is diastatic power?  Do I need to worry about it?  What other factors do I need to consider when formulating a recipe?

Answer:  Diastatic power is a measure of how much starch-converting enzyme any given malt contains.  When you make the jump from extract brewing to all-grain, you’ll want to make sure you have enough.  If you don’t, your mash will fall short of its intended starting gravity.  Fortunately, modern malts usually have plenty.  You will really only need to worry about it when your recipe has a large amount of grains without any diastatic power. 
Diastatic power is measured in degrees Lintner.  As a general rule of thumb, you want to make sure your mash averages 70 Linter or above.  With most recipes, this isn’t too hard to do.  Also note that heat can destroy diastatic power.  If this is your first mashing attempt, or if your temperature targeting is a bit off, I suggest you keep the diastatic power above 100 to be safe. 
Note that some malts have a lot of diastatic power.  6-row malt is the highest.  Others don’t have any, such as crystal malt, and anything that falls into the category of “unmalted”.  Specialty malts such as Munich malt are at the low end of the range.  Since most recipes use a lot of diastatic-containing malt and only small amount of non-diastatic, the total diastatic power is seldom a problem.  I’ll illustrate the calculation with a few examples.
Take a typical Pale Ale for example.  If you use 6 lb of 2-row Pale Ale malt (DP = 110) and 1 pounds of crystal malt (DP = 0) your average is 94 and you have nothing to worry about.  The mash should work fine. 
As another example, take my recent Witbier recipe, which had 3.5 lb Pilsner malt (DP = 125), 1.5 lb 6-row malt (DP = 150) and 5 lb of unmalted wheat (DP = 0).  Note that in this example, fully half of the grain had no diastatic power.  This averaged out to 66 Lintner.   As it turned out, I missed my target gravity on this recipe!   If I had substituted all the pilsner malt with 6-row malt, the DP would have been 75 Lintner, which would have worked.  Greg recently brewed his “Trit” beer using a mixture of 6-row malt and triticale, an unmalted grain.  His recipe hit the target gravity.  Another method would have been to replace some of the unmalted wheat with malted wheat.  Note that malted wheat has plenty of diastatic power. 
If you plan to brew with large amounts of zero diastatic grains, I suggest you use 6-row malt.  American lager for example typically uses 40% adjuncts such as corn or rice and the remainder is 6-row malt.   For most other recipes, you can use 2-row malt, which typically has a richer flavor. 

Diastatic Power as reported by
Cargill Malt Specialty Group:

Grain Type

Diastatic Power in Degrees Lintner

2-Row Pale Malt


6-Row Pale Malt


Highly modified Pilsner Malt


Malted Wheat


Vienna Malt


Munich Malt


Crystal Malt


Unmalted Wheat


Chocolate malt, roast barley


Unmalted Adjunct grains  (rice, corn)