Physicochemical and functional properties of the protein-starch interaction in Chinese yam.

Protein-starch interaction has an important impact on the properties of starchy foods rich in protein, but the contribution of the interaction to Chinese yam still remains unclear. This study aimed to characterize the physicochemical and functional properties related to the possible interaction between starch and protein in Chinese yam. Differential scanning calorimetry and rapid viscosity analyzer results revealed that the gelatinization temperature increased in protein and starch cross-linked powder, while the peak viscosity and the setback viscosity decreased. The swelling power and solubility at 80°C and 95°C decreased with increasing protein ratio in the powder. In vitro starch digestibility test indicated that a high protein ratio could rapidly reduce digestible starch, but increase both slowly digestible starch and resistant starch. Protein could act as the physical barrier toward starch against heating and digestion to exert the influence on starch properties. Fourier transform infrared spectroscopy test revealed the interaction between protein and starch. These results revealed the role of protein-starch interaction and provided beneficial information for the utilization of Chinese yam.