Physicochemical characterization of extruded blends of corn starch-whey protein concentrate-Agave tequilana fiber.

摘要

The objective of this work was to prepare extruded blends of corn starch supplemented with whey protein concentrate and Agave tequilana fiber (AF). The extruded blends were prepared by blending whey protein concentrate (WPC 80, 25%) with a mixture of corn starch (60%, 67%, and 74%) and A. tequilana fiber (1%, 8%, and 15%) and then adjusting its pH (5 and 8). The extrusion process was performed using a laboratory single-screw extruder. The screw compression ratio was 2:1 with a 5.0-mm die nozzle. Barrel temperature in the final zone was 140 degrees C. Small differences in expansion index and bulk density values were found between extruded samples with or without fiber addition, while the samples extruded at pH5 showed the lowest penetration force. Alkaline pH and high fiber content resulted in the highest total and insoluble dietary fiber. The addition of fiber to the extruded formulations decreased lightness, greenness (-a), and total color ( Delta E). AF incorporation increased water absorption index in all the assays, but these values were not significantly different. In vitro digestibility values varied between 83% and 90%, and the addition of AF in different levels did not change these values. The inclusion of AF into extruded blends of whey protein and corn starch reduced peak, minimum, and final viscosity but increased the extent of gelatinization when highest levels of AF were added in the blends. Extruded samples showed good functional characteristics with improved health benefits (more fiber and protein content) due to whey protein and fiber addition to starch.