Thermal stability of bovine lactoferrin prepared by cation exchange chromatography and its blends with authorized additives for infant formulas

The use of bovine LF as ingredient in infant formulas to mimic human milk composition is of great interest for the food industry; however, thermal treatments may induce denaturation of LF, reducing its nutritional benefits. In this study, the effect of four salts, authorized as additives for infant formulas (potassium phosphate (PP), sodium phosphate (SP), potassium citrate (PC) and sodium citrate (SC)), in the thermal stability of bovine LF, was studied. The concentration of soluble LF after applying different thermal treatments (90 degrees C, 2min and 120 degrees C, 30s) was determined by UPLC, while the structural changes induced by the additives were studied by zeta-potential, CD and DSC analyses. The results evidenced that LF undergoes thermal denaturation under the tested conditions. The addition of SP, PC and SC led to more negative surface charges and promoted a greater degree of unfolding. Contrarily, the LF-PP blend presented a slightly acidic pH and neutral charge and showed the same unfolding degree than LF alone. Interestingly, PP induced partial re-naturation upon cooling. In addition, the results show that PP and SC do not prevent the denaturation of LF, but they inhibit aggregation, keeping a relatively large proportion of soluble LF after the application of heating treatments.