Physicochemical properties of nixtamalized black bean (Phaseolus vulgaris L.) flours.

The aim of this work was to study the effect of three nixtamalization processes using wood ashes, Ca(OH)2, and CaCl2 on the physicochemical properties of beans. Raw beans had C-type starch, 10.10% resistant starch (RS), and two DSC endotherms: 1) starch gelatinization, and 2) melting of amylose-lipid complexes plus protein denaturation. Nixtamalization increased the Ca and Fe content, decreased the RS content to 4.19-4.43%, and produced starch retrogradation. DSC and FT-IR analysis of the flours evidenced a "stabilizing" effect of cooking with NaCl and CaCl2 on bean proteins. In contrast, cooking with wood ashes and Ca(OH)2 produced denaturation of bean proteins, decreasing the second transition enthalpy and absorption bands of amide I, II and III. Results showed that traditional and classic nixtamalization of beans are alternatives to obtaining mineral fortified flours that could be used as ingredients in the elaboration of foods with a good nutritional profile.