Nixtamalisation of maize (Zea mays L) using a single screw cook‐extrusion process on lime‐treated grits

The tortilla flour market is expanding but present industrial production is lagging behind in the use of modern technologies to increase production and cut costs due to the maize steeping and drying operations. A process using a single‐screw cook‐extruder which eliminates the traditional steeping and drying operations was therefore explored. Lime (Ca(OH)2) suspension was absorbed onto commercial maize grits (2 g lime kg−1 maize) and the resulting meal conditioned to various moisture contents. These samples and one which had not been lime‐treated were cook‐extruded through a Brabender Do‐corder extrusion cooker (Type 825602). The dry extrudate was milled through a 150 μm sieve and tortillas made from each sample. The tortillas prepared from the lime‐treated grits conditioned to 472 g kg−1 moisture compared favourably with that prepared from traditionally prepared masa flour when organoleptically assessed. Flour pasting properties (viscosity) and water absorption index were not significantly different (P < 0.05) from the traditionally prepared products. Enzyme susceptible starch index did not correlate well with dough quality.