Reaction kinetics of the corn pericarp during the nixtamalization

We studied by grazing incidence X-ray diffraction the behavior of the amorphous and crystalline diffractogram areas of corn pericarp samples taken during a typical nixtamalization process. The pericarp amorphous part suffers two dissolution processes, one fast, due to the dissolution of the water- and alkali-soluble parts of the pericarp, and other slow, associated with the hemicelluloses dissolution. During the steeping stage the crystalline part of the pericarp reflects the transformation of the native cellulose under the alkaline treatment into cellulose II, meanwhile, the amorphous part increases due to the alkaline cellulose transformation into amorphous II-type cellulose. Assuming first-order reactions we fitted the area behaviors in the steeping stage and found the reaction rates from native cellulose into alkaline cellulose and from alkaline cellulose into cellulose II to be k₁≅ 0.027 min _-1 and k₂ ≅ 0.00077min^-1 respectively.