Table tortillas are highly popular in United States, Canada and some European countries. The expanded consumption of tortillas has led to industrialization of the nixtamalization process for dry masa flour (DMF) production. However, masa production atthe industrial level does not exactly follow the traditional nixtamalization conditions. The objective of the present study was to evaluate the influence of cold storage on the in vitro digestibility of starch in tortilla made with commercial nixtamalized flours. Nixtamalized maize flours elaborated by four factories in Mexico were used for tortilla preparation. Samples were stored at 4 for up to 72 hours and their in vitro starch digestibility features were evaluated. Moisture content was different between flour and tortilla, but no evident relation could be established. Protein and lipid levels were lower in tortillas than in flour, but ash content was not different in both samples. A decrease in available starch content was observed upon 48 h coldstorage (4), changes that were concomitant with increased total resistant starch (RS) levels. These changes were due mainly to retrogradation, as suggested by the increased retrograded resistant starch (RRS) levels recorded in stored tortillas; in some samples, RRS represented up to 100% of total RS. The digestion (alfa-amylolysis) rate (DR) of freshly prepared tortillas differed for the various samples. Although the amylolysis patterns for fresh and 72 h-stored tortillas were similar, lower DR values were shown for the stored materials. The differences found among the various tortilla samples may be due to variations in processing conditions during commercial maize flour preparation, and to the use of different maize varieties.
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