Effect of Calcium Hydroxide and Nixtamalization Time on the In Vitro Starch and Protein Digestibility of Traditional Maize Tortillas

This work addressed the traditional nixtamalization processing conditions on the in vitro protein and starch digestibility of tortillas. Two levels of lime addition (1 and 2 g/100 g db) and three different cooking times (30, 45 and 60 min) were considered. FTIR analysis was used to evaluate the organization of water, proteins and starch in the tortilla matrix. Lime concentration impacted the random secondary structure formation of the protein, and cooking time the starch ordered structures content. Higher lime concentration led to lower protein digestibility, but longer cooking time increased it. Highest protein hydrolysis (74.36 ± 3.72%) was achieved in T_1,60 after 120 min of enzymatic digestion. Higher RDS contents were found as lime concentration increased, probably due to starch chain fragmentation at all cooking temperatures. A multivariate analysis indicated that both the lime concentration and cooking time had a major effect on the tortilla's digestibility. Both protein and starch digestibility can be modulated by using appropriate lime concentrations and cooking temperatures.