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

ABSTRACT

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 ß112 dominated the change in total carotenoids, lutein, zeaxanthin, and ß-carotene. The quadratic coefficients were also important for changes in total color (regarding feed moisture), and for ß-cryptoxanthin, specific mechanical energy, and volumetric expansion index (regarding barrel temperature). ß-cryptoxanthin and ß-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 ß-carotene and ß-cryptoxanthin were produced. The use of richer cultivars in carotenoids could contribute to the production of healthier snacks.