Nixtamalization and its impact on the physicochemical, bioactive, and antioxidant properties of Cucurbita pepo, Cucurbita argyrosperma, and Cucurbita maxima

Nixtamalization is a traditional process which involves alkaline cooking and improves the food properties. Cucurbits are sensitive to the physical damage caused by temperature changes, which hinders their commercialization. Therefore, nixtamalization could be an alternative for the processing, handling, and use of these fruits. This study aimed to evaluate the effect of nixtamalization time (0, 2, 4, 6, 8, 10, 12, 14 min) on the evolution of the physicochemical, bioactive, and antioxidant properties of three species of cucurbits (Cucurbita pepo, Cucurbita argyrosperma, and Cucurbita maxima). After nixtamalization, cucurbits were dehydrated (60 °C, 24 h), ground, and sieved (500 μm). Subsequently, physicochemical properties were analyzed, and total bioactive compounds and antioxidant capacity were determined through spectrophotometric techniques. Polyphenolic compounds (via HPLC) and calcium were quantified 6 min after nixtamalization. According to the results, nixtamalization increased pH (9–19 %) and moisture (1–2 %) and reduced hardness by up to 97 %. The color became darker and more intense, with a decrease in lightness (8–19 %) and hue angle (2–9 %) and an increase in chroma (13–23 %). Furthermore, chlorophyll (44–80 %), carotenoids (25–39 %), and antioxidant capacity (14–37 %) increased. Finally, phenolic acids (gallic, chlorogenic, and syringic) and flavonoids (epicatechin, catechin, and myricetin), and calcium levels were higher (65–93 %) in nixtamalized flours. In conclusion, nixtamalization can be used as a novel strategy for preserving cucurbits and increasing their chlorophyll and carotenoid contents. This approach could reduce post-harvest losses by allowing the use of waste products and the development of functional ingredients.