Exploring the influence mechanism of water grinding on the gel properties of corn starch based on changes in its structure and properties.

BACKGROUND: At present, most studies have focused on the preparation of modified starches by dry grinding. As an excellent starch plasticizer, water might enhance the action of grinding on the structure of starch granules, and water grinding might improve the gel properties of starch. Therefore, this article explored the influence mechanism of water grinding on the gel properties of corn starch based on the changes in its structure and properties. RESULTS: The results showed that water grinding could make water enter the starch granules and hydrate the starch molecules, and the starch gelatinized after water grinding for 20 min. Thus, water enhanced the action of grinding on the structure of the starch granules. Under the plasticization and grinding action of water grinding, the mechanochemical effect of the starch granules occurred. When the starch was in the aggregation stage (7.5-10 min), the crystallinity of the starch increased, and the starch molecules rearranged into a more stable structure, which increased apparent viscosity (η), elastic modulus (G') and viscous modulus (G″) of the starch gels. CONCLUSION: Therefore, appropriate water grinding (10 min) contributed to increasing the viscoelasticity of starch gels. This study provided a theoretical foundation for research on improving the properties of starch by mechanical modification in future. © 2023 Society of Chemical Industry.

Surface analysis of novel fibroin films based on well-preserved crystalline structures.

We recently reported that a highly homogeneous aqueous suspension of fibroin nanofiber (FNF) can be simply obtained by mechanical water-grinding a heterogeneous aqueous fibroin slurry and that the FNF in the suspension preserves the native ß-sheet secondary structure during this mechanical treatment. The current study reports the surface properties of well-preserved crystalline structure novel FNF film from water-grinding preparation as compared with those of typical, conventionally prepared regenerated fibroin (RF) film. RF film was not treated with alcoholic solutions and was verified to be amorphous from a WAXD diffraction diagram. The air-side surfaces of the FNF semi-crystalline and RF amorphous films were studied to clarify differences using scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), static water contact angle, and X-ray photoelectron spectroscopy (XPS). The well-preserved crystalline in the FNF film was found to exist near a slightly deep surface region and to act as a physically cross-linking domain, governing the molecular motions of the amorphous polypeptide chains at the very shallow surface region.