Effect of in vitro digestion-fermentation of Ca(II)-alginate beads containing sugar and biopolymers over global antioxidant response and short chain fatty acids production.

The aim of the present paper was to unravel the effect of a standardized in vitro European protocol of digestion-fermentation over Ca(II)-alginate beads synthesized with sugars and biopolymers. Special emphasis on the antioxidant capacity using methods that simulate physiological conditions, short-chain fatty acids (SCFAs) production, and a detailed study of the microstructure of the gel network by SAXS at several scales (1-100 nm) were considered. Beads released high antioxidant capacity during digestion assessed by several methods, comparable to some common foods; antioxidant capacity was improved with sucrose and arabic gum inclusion in the formulation. After fermentation by gut microbiota, a ten-fold increase in the antioxidant values and an important SCFAs production were obtained, revealing the enhanced ability to produce these functional biomolecules. The microstructural analysis of Ca(II)-alginate showed an advantageous behavior: they slightly changed in oral and gastric fluids and partially dissolved their structure in intestinal fluid, where absorption occurs.