Effects of synergistic modification using alkalis and guar gum on the pasting, rheological, and microstructural properties of germinated highland barley starch gels

Germination treatment of highland barley enhances its nutritional value while weakening the starch gel properties. This study aims to enhance the characteristics of germinated highland barley starch (GBS) by exploring the synergistic effects of two alkalis (Na2CO3 and NaHCO3) and guar gum (GG) on GBS gel properties. The combined action of alkalis and GG significantly improved the peak viscosity, setback viscosity, and hardness compared with GG alone. The highest G' and G" reached 998 and 204 Pa at 0.4% Na2CO3 addition, which were increased by nearly 44% and 50%, respectively. Fourier-transform infrared spectral analysis revealed that the alkalis strengthened interaction forces, particularly with intensified absorption peaks at 3200–3700 cm−1 and 1550–1750 cm−1. The Na2CO3 and NaHCO3 reduced the spin–spin relaxation time (T2), resulting in a dense starch gel network. This study contributes to enhancing the market application of GBS and offers innovative insights for modifying other starches.