Structural, physicochemical, and digestive properties of starch-tannic acid complexes modulated by co-heating temperatures

The effect of co-heating temperature on the functional features of tannic acid-starch complexes has been a research gap in the field of food processing. In this study, tannic acid-corn starch (TA-CS) complexes were coprepared at different temperatures (25, 50, 70, and 95 degrees C), and their structural, physicochemical, and digestive properties were examined. Results from High-Performance Liquid Chromatography (HPLC) and DPPH radical scavenging indicated that higher preparation temperatures led to increased binding between TA and CS, resulting in stronger antioxidant properties of TA-CS complexes. Iodine Binding Capacity (IBC), X-ray Diffraction (XRD), and Fourier Transform Infrared (FT-IR) results revealed that, at elevated preparation temperatures (50, 70, and 95 degrees C), TA and CS form V-type complexes mediated not only by hydrogen bonding but also by hydrophobic interactions. Differential Scanning Calorimetry (DSC) results showed that with increasing TA concentration, complex gelatinization was promoted at 25 degrees C and 50 degrees C but inhibited at 70 degrees C and 95 degrees C. Thermogravimetric Analysis (TGA) indicated that higher preparation temperature (95 degrees C) was detrimental to the enhancement of CS-TA thermal stability. In vitro digestion results demonstrated that complexes prepared at 70 degrees C and 95 degrees C exhibited stronger resistance to digestion, displaying higher blood glucose control levels and nutritional value compared to those prepared at 25 degrees C and 50 degrees C. This study enhanced our understanding of the impact of co-heating temperatures on CS-TA interactions, providing new insights for developing health-oriented starch-based foods utilizing polyphenols.