Characterization of prebiotic oligosaccharides-starch interactions and their effects on wheat starch properties under...

The changes in the structure, gelatinization, and rheological properties of wheat starch during freeze-thaw cycles are crucial for enhancing the quality of products. This study investigated the effects of oligosaccharide (16 % w/w) addition on starch structure and properties under repeated freeze-thaw (FT) conditions. Specifically, xylooligosaccharides (XOS), galactooligosaccharides (GOS), and fructooligosaccharides (FOS) were found to preserve the supramolecular stacking of starch after the unwinding and amorphization of the native starch molecules. Notably, XOS more effectively inhibited the reorganization of starch structures after freezing and thawing, which could reduce the setback viscosity by 39.3 % after 11 freeze-thaw cycles. This inhibition likely prevents water molecules from entering granules and forming hydrogen bonds with starch chains, thereby limiting the development of helical and short-range ordered structures. Furthermore, the XOS curtailed the formation of long-range ordered structures in the crystalline region. These effects contribute to the increased shear resistance and structural recovery of the starch paste after shearing. Additionally, the presence of oligosaccharides led to reductions in both storage and loss moduli resulting in a relatively weak gel network structure. This study provides valuable insights into the selection of functional sugar substitutes for frozen products during freeze-thaw cycles.