Lactoferrin as a carrier of iron: Development and physicochemical characterization

Iron deficiency is the main cause of anemia, one of the most common nutritional deficiencies affecting millions of people worldwide. In addition, iron instability, sensitivity, and intense flavor limit its use in food fortification. In this work, lactoferrin (LF) particles were developed by Nano Spray Dryer (NSD) and its capacity to be used as an iron carrier was evaluated. The effect of NSD temperature (60 °C, 80 °C, and 100 °C) and LF concentrations (10 mg mL−1, 50 mg mL−1, and 100 mg mL−1) was evaluated on the LF structure and on the production and stability of a LF-iron carrier. Results showed that the NSD is suitable for producing LF particles with diameters ranged from 38.8 nm to 4533.6 nm. Although different surface morphologies were obtained, higher protein concentrations (100 mg mL−1) produced round shape and smooth surface particles, but for lower protein concentrations (10 mg mL−1 and 50 mg mL−1) wrinkled particles and doughnut shape particles were obtained. SDS-page electrophoresis and circular dichroism (CD) for secondary structure (185–260 nm) show that the characteristics of the structures were maintained, meaning that NSD does not cause protein degradation. CD for tertiary structure (250 nm–350 nm) and fluorescence tests confirmed the interaction between LF and iron, observed by an intensity decrease and a wavelength shift in fluorescence spectra. The CD tertiary structure analysis showed higher ellipticity for the Trp peak, meaning conformational changes in the neighbor amino acids due to protein-iron interaction. Iron release experiments were performed at different pH values (2.0 and 7.4) at 37 °C aiming to understand the release mechanism in different media. Results showed that at pH 2 the iron release could be described by the linear superposition model (Radj2 = 0.9879) (explained by Fick and relaxation phenomenon) and that at pH 7.4 there is no iron release, showing that particles are stable at neutral pH. NSD is a suitable technology for producing iron-loaded protein-based carriers that could be used in food applications.