Interaction characterization of preheated soy protein isolate with cyanidin-3-O-glucoside and their effects on the stability of black soybean seed coat anthocyanins extracts.

Affiliation

Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, PR China. Electronic address: [Email]

Abstract

The interactions of soy protein isolate with cyanidin-3-O-glucoside were investigated to study the protective effect of protein on anthocyanin's stability by UV-Vis spectrophotometry, Fourier transform infrared spectroscopy, circular dichroism and fluorescence spectroscopy. Preheat treatment and binding of cyanidin-3-O-glucoside effectively changed the secondary structure of soy protein isolate, with a decrease in α-helix, random coil structure and an increase in β-sheet and β-turn. The soy protein isolate preheated at 121 °C exhibited a strong binding affinity towards cyanidin-3-O-glucoside with strong Ks of 147.40 × 104 M-1 and also effectively increased the thermal and oxidation stabilities of black soybean seed coat extract via decreasing the degradation rate by 67% and 23%, respectively. Soy protein isolate interacted with cyanidin-3-O-glucoside mainly through hydrophobic interactions and static quenching process. Altogether, the results suggested that preheated soy protein isolate-cyanidin-3-O-glucoside interaction could effectively protect anthocyanins' stability through strong binding affinity influenced by the systematic alterations in the secondary structure.

Keywords

Anthocyanins,Black soybean,Cyanidin-3-O-glucoside,Cyanidin-3-O-glucoside (PubChem CID: 185664),Disodium hydrogen phosphate (PubChem CID: 71180),Hydrochloric acid (PubChem CID: 313),Hydrogen peroxide (PubChem CID: 784),Interaction,Potassium bromide (PubChem CID: 253877),Potassium chloride (PubChem CID: 4873),Sodium acetate (PubChem CID: 517045),Sodium dihydrogen phosphate (PubChem CID: 24204),Soy protein isolate,Stability,Tryptophan anion (PubChem CID: 3090777),Tyrosine cation (PubChem CID: 5460804),