Physical Characterization of Maize Grits Expanded Snacks and Changes in the Carotenoid Profile

The objective of this work was to evaluate the effects of feed moisture (13-17%, wb) and barrel temperature (120-160 °C) on physicochemical properties, and changes in the carotenoid profile of maize grits extruded snacks. The extrudates were obtained in a single-screw extruder, according to a 3² factorial design with two replicates. The linear coefficients of feed moisture and barrel temperature mainly affected the physicochemical properties. On the other hand, the interaction coefficient β₁₁₂ dominated the change in total carotenoids, lutein, zeaxanthin, and β-carotene. The quadratic coefficients were also important for changes in total color (regarding feed moisture), and for β-cryptoxanthin, specific mechanical energy, and volumetric expansion index (regarding barrel temperature). β-cryptoxanthin and β-carotene increased, whereas lutein and zeaxanthin decreased. The mathematical models developed from responses revealed two feasible operating regions under the domain explored. For a satisfactory process, from a technological and nutritional point of view, it is suggested to extrude at the operating conditions ranging between 13.2-13.7% feed moisture and 120-132 °C barrel temperature. Under these conditions, the specific mechanical energy input required was 410-450 kJ/kg, and extrudates with a volumetric expansion index greater than 12, a crispness work less than 0.4 N.mm, and with moderate increments in the levels of β-carotene and β-cryptoxanthin were produced. The use of richer cultivars in carotenoids could contribute to the production of healthier snacks.