Chemical composition and starch digestibility of tortillas prepared with non-conventional commercial nixtamalized maize flours.

Non-conventional nixtamalized maize flours elaborated by a factory in Mexico were used for tortilla preparation. Tortillas were stored at 4 degrees C for up to 72 h and the total starch, available starch, resistant starch and retrograded resistant starch were assessed. The traditional white tortilla, used as a control, showed higher protein and fat contents than blue maize tortilla, whereas a maize-bean mixed tortilla had the highest protein, ash and fat contents. Lower total starch was obtained in the maize-bean tortilla than in white and blue maize tortillas. The available starch content in all tortillas decreased with the cold-storage, although the change was more marked for blue-maize tortillas. The maize-bean mixed tortillas exhibited the lowest in vitro digestibility, which is consistent with the relatively high resistant starch levels in the bean. Differences in resistant starch content were found between the two maize tortillas, which might be related to the softer texture of blue-maize tortilla. The starch digestibility features of these new types of nixtamalized maize flours open up the possibility of producing tortillas with variable nutritional properties.