Modifying the mechanical strength and network structure of starch gel through ethanol-water solution soaking.

This study investigated the effects of soaking potato starch gels in ethanol solutions of varying concentrations and for different durations on the properties of the gels. Short-term soaking in 30 % ethanol significantly enhanced the tensile strain of the starch gels and increased the pore size and coarseness of the gel network structure. The tensile strain of starch gel increased more than twice after soaking in 30 % ethanol solution for 10 min (from 439.66 % to 761.11 %), although the further soaking can reduce this enhancement. In contrast, soaking in low-concentration ethanol caused water absorption and swelling of the gels, while high-concentration ethanol led to dehydration and plasticization of the starch. Subsequent structural analysis revealed that ethanol soaking significantly affected the solvent content, water distribution, and rheological properties of the starch gels. However, the soaking process had minimal impact on their crystalline structure, which indicated that the modification of the gels by ethanol is likely due to the rearrangement caused by the differential affinity of starch to the solution, independent of the retrogradation process that can influence gel properties. This study presented a novel approach for enhancing the mechanical properties of starch gels using a simple ethanol soaking method. This new method offered promising potential for producing high-performance starch hydrogels and may find future applications in the fields of food and natural organic materials.