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Preparation of High-Quality Protein-Based Extruded Pellets Expanded by Microwave Oven

¹Maestría en Ciencia y Tecnología de Alimentos, Universidad Autónoma de Sinaloa, Apdo. Postal 1354, Culiacán, Sin., C.P. 80000, México. Phone: (52) 667 7136615. Fax: (52) 667 7136615. E-mail: zazuetaj@uas.uasnet.mx ²Ciencia de Materiales, CINVESTAV Querétaro, Apdo. Postal 1-798, Querétaro, Qro., C.P. 76230, México. Phone:(52) 442 4414905. Fax: (52) 442 4414938. ³Corresponding author. E-mail: fmartinez@qro.cinvestav.mx

The aim of this work was to study the effects of extrusion barrel temperature (75–140°C) and feed moisture (16–30%) on the production of third-generation snacks expanded by microwave heating. A blend of potato starch (50%), quality protein maize (QPM) (35%), and soybean meal (SM) (15%) was used in the preparation of the snacks. A laboratory single extruder with a 1.5 × 20.0 × 100 mm die-nozzle and a central composite routable experimental design were used. Expansion index (EI) and bulk density (BD) were measured in expanded pellets, viscosity at 83°C (V₈₃), thermal properties, and relative crystallinity were measured in extruded pellets. EI increased and BD decreased when the barrel temperature was increased, while the feed moisture effect was not significant. V₈₃ increased when feed moisture increased. Extrusion modified the crystalline structures of the pellets and the X-ray data suggests the formation of new structures, probably due to the development of amylose-lipid complexes. The maximum expansion of pellets was found at barrel temperatures of 123–140°C, and feed moisture of 24.5–30%. It is possible to obtain a functional third-generation snack with good expansion characteristics using a microwave oven, and this snack has health benefits due to the addition of QPM and SM.