Efficient Retention and Complexation of Exogenous Ferulic Acid in Starch: Could Controllable Bioextrusion Be the Answer?

The starch-phenolics complexes are widely fabricated as functional foods but with low phenolics retention limited by traditional liquid reaction and washing systems. In this study, ferulic acid (FA, 5%) was exogenously used in the crystalline form, and it reacted with starch in a high-solid extrusion environment, which was simultaneously controlled by thermostable a-amylase (0-252 U/g). Moderate enzymolysis (21 or 63 U/g) decreased the degree of the starch double helix and significantly increased the FA retention rate (>80%) with good melting and distribution. Although there were no significantly strong chemical bonds (with only 0.17-2.39% FA bound to starch hydrolysate), the noncovalent interactions, mainly hydrogen bonds, van der Waals forces, and electrostatic interactions, were determined by H-1-NMR and molecular dynamics simulation analyses. The phased release of total FA (>50% in the stomach and similar to 100% in the intestines) from bioextrudate under in vitro digestion conditions was promoted, which gives a perspective for handing large loads of FA and other phenolics based on starch carrier.

Automated summary

In this study, the combination of high-solid extrusion and moderate enzymolysis was utilized to enhance the binding efficiency of starch and phenolics. The phased release of phenolics was achieved, and noncovalent interactions were found to play a crucial role in the binding process.