Effects of Ultra-High Pressure-Cellulase Pretreatment on the Structural Characteristics and Functional Properties of Soluble Dietary Fiber from Perilla Seed Hulls and Its Application in Wheat-Corn Composite Dough.

Perilla seed hulls are a promising but underutilized source of dietary fiber, yet little is known about how pretreatment-induced structural changes in soluble dietary fiber (SDF) derived from these hulls affect its functionality in cereal dough. This study compared SDF extracted from untreated, ultra-high-pressure (UHP)-pretreated, cellulase-pretreated, and sequentially UHP-cellulase-pretreated perilla seed hulls and evaluated their structural, physicochemical, and dough-modifying properties. The combined treatment increased the SDF content of the hull material from 3.71% to 8.63% and decreased insoluble dietary fiber from 55.74% to 50.37%. Relative to untreated SDF, the resulting UCPSDF had a lower apparent molecular weight (2442 vs. 2788 Da), a smaller mean particle size (2.76 vs. 3.62 μm), a lower glucose proportion, and higher arabinose and acidic monosaccharide proportions. FTIR, XRD, SEM, and thermal analyses indicated retention of the principal polysaccharide and cellulose-I signatures, accompanied by changes in structural characteristics and a looser, more porous morphology. UCPSDF also showed the highest water-holding and swelling capacities. At 6% supplementation, UCPSDF produced the strongest elastic response in wheat-corn composite dough, significantly increased springiness (0.59-0.72) and cohesiveness (0.64-0.76), increased the combined amide I-derived α-helix and β-sheet proportion of dough proteins from 53.93% to 66.82%, and reduced the T23 relaxation time from 297.86 to 81.23 ms. These findings indicate that sequential UHP-cellulase pretreatment improves the measured SDF content and hydration functionality of perilla seed hull SDF and supports its use as a dough-structuring ingredient in wheat-corn composite foods.