Alginate and corn starch mixed gels: Effect of gelatinization and amylose content on the properties and in vitro digestibility.

ABSTRACT

The aim of this work was to evaluate the effects of gelatinized and non-gelatinized corn starches with different amounts of amylose (6.62, 28.46, and 61.10%) in the alginate matrix in relation to mechanical properties and microstructure before and after in vitro digestibility. The use of alginate together with corn starch with different amounts of amylose, in the gelatinized and non-gelatinized form, resulted in gels with different morphological characteristics. All hydrogels produced with gelatinized starches showed a more closed microstructure when compared to those produced with non-gelatinized starches due to the mixed network formed by the alginate matrix and the leached chains during gelatinization. After digestion, the microstructure of these gels became more porous, and the stress at rupture decreased in relation to the initial sample, while the modifications for the sample with non-gelatinized starches were less pronounced due to the susceptibility of gelatinized starch to enzymes. Gels with gelatinized common and high amylopectin starches presented higher amounts of released glucose and a more degraded microstructure after digestion, indicating that it is a suitable system for enteric delivery. Compound release can be controlled depending on the amylose amount and the form of corn starch used in combination with alginate to produce a matrix.