Two kinds of maize--both non-hybrids similar to premodern maize--were used: 

  Iroquois White, a "flour" corn.

    Cherokee Blue-and-White Dent, a "dent" corn. 

We prepared a lye solution (pH 11.3) with 0.5 kg eastern hardwood ash mixed in 6 liters water.

Experimental protocol for each sample:

A.  50 g of dry kernels were boiled for 5, 10, 15, 20, or 30 minute intervals in 200 ml of lye solution (or water for control samples).

B.  After boiling, samples were pounded in the mortar for 400 strokes (approx. 20 minutes).

C.  Pounded sample was shaken for 30 seconds in a #10 sieve (2.0 mm) to separate screen-retained hulls from bottom-pan grits.

D.  Dry weights were recorded.