Influence of Ternary Complexation between Bovine Serum Albumin, Sodium Phytate, and Divalent Salts on Turbidity and In Vitro Digestibility of Protein

Phytate decreases mineral and protein availability and influences protein properties, such as solubility and stability. The binding constants and turbidity data can help with the understanding of the influence of phytate and divalent salts on protein behavior. Ternary complexes formed between bovine serum albumin, sodium phytate, and divalent salts were investigated by isothermal titration calorimetry, turbidity, and in vitro protein digestibility. Results showed a positive entropy change and a negative and small enthalpy change as a result of electrostatic binding forces and ternary and binary complex precipitation. The interaction was favored for the systems containing calcium and manganese, whereas those containing magnesium showed a low heat of interaction. Despite the high protein digestibility, the stability of divalent phytates in a wide pH range may decrease mineral bioavailability. These results can provide important insights for the study of mineral bioavailability and diverse processes that involve protein and minerals in several areas of knowledge.