Effect of pulsed electric field and thermal treatment on the physicochemical properties of lactoferrin with different iron saturation levels

Bovine lactoferrin (LF) with different iron saturation levels (i.e., native (N-) LF, Apo-LF and Holo-LF) dissolved in simulated milk ultrafiltrate was treated by pulsed electric fields. Various heat treatments were conducted as comparisons. The concentration of LF, electrophoretic mobility of the proteins, surface hydrophobicity and the release of LF-bound ferric ions to the aqueous phase of the LF preparations after the PEF or thermal treatments were determined. PEF treatments did not affect the physicochemical properties of Apo-LF, N-LF, or Holo-LF at treatment temperatures ≤50, ≤60, ≤65 °C, respectively. Changes in LF properties at higher temperatures were largely or entirely due to concurrent thermal effects during PEF treatments. The thermal stability of LF correlated with the level of iron saturation. These results will be useful when developing a PEF process for microbial inactivation of LF-containing dairy products with the aim of maximising the retention of this heat-sensitive protein.