Curcumin Stabilization and Starch Structural Changes in Gels Based on Enzymatically Modified Surplus Rice Cake Flour

In this study, surplus rice cake flour (RCF), a by-product of rice cake production, was enzymatically modified using cyclodextrin glucanotransferase (CGTase) to produce curcumin-stabilized rice cake flour gel (cRCF).Scanning electron microscope observations revealed the presence of particle-like structures, presumably derived from curcumin, on the cRCF pore walls and boundary surfaces.High-performance liquid chromatography confirmed that the curcumin content in cRCF 100 was significantly higher than in untreated RCF (P<0.05).Furthermore, high-performance anion-exchange chromatography revealed decreases in short-chain regions (DP 5-15) and increases in intermediate and long-chain (DP≥31) regions, with these changes being most pronounced in cRCF 100.This study shows that an enzymatic treatment can improve the dispersibility and solubility of curcumin, leading to the increased retention of curcumin within the gel matrix.Through this approach, the upcycling of surplus rice cake flour enhances its potential as a high-value functional material.