The Collaborative International Dictionary of English v.0.48:

Diastatic \Di`a*stat"ic\, a. [Gr. ? separative. See Diastase.]
   (Physiol. Chem.)
   Relating to diastase; having the properties of diastase;
   effecting the conversion of starch into sugar.
   [1913 Webster]

         The influence of acids and alkalies on the diastatic
         action of saliva.                        --Lauder
                                                  Brunton.
   [1913 Webster]