Self-assembling soy protein fibril aggregates: Characterization and impact on in vitro digestibility of potato starch

This study is focused on the characteristics of thermally induced fibril aggregates originating from soybean protein (SPFA), and the impacts of the SPFA on digestive, structural, and physicochemical properties of potato starch (PS). The SPFA, caused by heating for various heating periods at 85 °C and low pH, displayed significantly different structural changes, morphological characteristics, and particle size distributions. The results revealed that the presence of SPFA could improve the degree of short-range order and forms more compact structure than the PScontrol. The SPFA increased thermal stability, reduced pasting viscosity, and delayed short-term retrogradation of PS. And the non-covalent interactions between PS and SPFA were enhanced under cooking conditions. The fraction of digested starch at 300 min (C300) content of the PS-SPFA complex was reduced by 8–20%, while the C300 of the PS-SPFA mixture reduced only 1–4%. The SPFA with longer thermal treatment (16, 24 h) displayed significant lower rapid digestible starch content (RDS) and higher slowly digestible starch (SDS) than those with shorter thermal treatment (2, 8 h). This study is expected to deepen the understanding of the interaction between food components, enrich the theory of protein regulation of starch digestion.