The in vitro digestibility of starch fractions in maize tortilla can be rendered healthier by treating the nixtamalized masa with commercial baking yeast

Baking yeast exhibiting amylolytic activity was used for treating masa made from nixtamalized maize flour (NMF). Baking yeast (0.25, 0.50 and 1.0 g.100 g(-1) NMF) was added to the basic masa recipe (40 NMF:60 water mass ratio). Two masa controls without yeast addition were prepared: CM1 used as such, and CM2 subjected to a mild incubation treatment (2h, 38 degrees C). Tortillas were made (350 degrees C, 1.0 min) with the yeast-treated masa. Baking yeast reduced total sugars, apparent amylose and viscoelasticity of the masa. Tortillas made with treated masa exhibited significant lower hardness than tortillas made with CM1 and CM2, and this effect was more pronounced in the tortillas stored for 4 days. Tortillas freshly made from yeast-treated masa displayed reduced RDS and SDS, but increased RS fractions. When stored for 4 days, they showed reduction in RDS, but an increase in SDS and RS fractions (similar to 30%) with respect to tortillas made with CM1 and CM2. Hardness of the yeast-treated tortillas was significantly lower and remained practically without change during storage, while the untreated tortillas hardened significantly. Treatment with baking yeast induces beneficial health and textural effects in tortillas.