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 α-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 1H NMR and molecular dynamics simulation analyses. The phased release of total FA (>50% in the stomach and ∼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.

Heat-induced conversion of multiscale molecular structure of natural food nutrients: A review.

Thermal process is the most important way of treating foods. Heat energy inputted into the natural food system induces the depolymerization of multi-scale structures of matrix, and causes the intramolecular and intermolecular interactions of different nutrients. It attacks and breaks the original polymeric molecule structures and the functional properties of macronutrients such as carbohydrates, proteins and lipids. Micronutrients such as vitamins and other novel functional ingredients are also thermally converted. The heat-induced conversions of nutrients are slightly or totally with discrepancy in simple-, simulated- and real-food systems, respectively. Thus, this review aims to extensively summarize the heat-induced structural characteristics, thermal conversion pathways and pyrolysis mechanism of nutrients both in simple and complex food matrices. The structural change of each nutrient and its thermal reaction kinetics depend on the molecule structure and polymeric characteristic of the unit substances in the system.

Bifunctional Fe3O4 nanoparticles as magnet and inducer in bioextruded fabrication of starch-based composite with hierarchical pore architecture.

Starch (St) was used as green and renewable matrix (> 80%, db) for the preparation of Zn-St-MOCP/nFe3O4 composite via bioextrusion. Bifunction of Fe3O4 NPs as magnet and pore-inducer was confirmed and could be more homogeneously embedded in the St-based framework with hierarchical porous structure via SEM-EDS mapping. For the nFe3O4-induced microstructure of Zn-St-MOCP/nFe3O4 composite, submicronic pores and nanopores were observed with Fe3O4 NPs onto the inner surface of micron channels. According to the XPS, XRD, FTIR, TGA analyses, it is probably due to the coordination between Fe3+/2+ and Zn2+/hydroxy groups and the recombination of St chains in crystalline/amorphous zones interfered by Fe3O4 NPs. Saturation magnetization value was measured with an excellent separation behavior. Seven kinetic equations were conducted for the fitting of dye adsorption data. Overall, the nFe3O4-assisted bioextrusion strategy is developed for the continuous fabrication of bio-based materials with rapid magnetic separation and hierarchical-pore architecture promising in practical adsorption.