Interaction of Quillaja bark saponin and bovine serum albumin: Effect on secondary and tertiary structure, gelation and in vitro digestibility of the protein
Elaine Kaspchak, Cíntia Tiemi Misugi Kayukawa, Joana Léa Meira Silveira, Luciana Igarashi-Mafra, Marcos R. Mafra
The interaction of Quillaja bark saponin and bovine serum albumin was determined by isothermal titration calorimetry and correlated to the structure, gelation and in vitro digestibility of the protein. Results showed that the interactions occur at around 0.5:1.0 mass ratio of saponin to protein at 25 °C resulting in a low heat of interaction and non-specific binding. Formation of saponin and protein complexes was favored at a higher temperature (75 °C), probably due to the exposure of different groups of the protein. The saponin increased the strength of the protein gels, due to the exposure of hydrophobic regions of the protein, as well as due to crosslinking between protein molecules. The protein digestibility was not greatly affected at a saponin to protein mass ratio smaller than 2.5: 1.0. Thus, QBS can be used to increase the protein gel strength and the health benefits of food without a significant impact on protein digestibility.
Circular dichroism, Chemical stability, Secondary structure, Tertiary structure, Biochemistry, Food science