Effects of high pressure processing on structure and emulsifying properties of lactoferrin-xanthan gum complex

The influence of high pressure processing (HPP) and polysaccharides on the structure and emulsifying properties of lactoferrin (LF) has been investigated by fluorescence, circular dichroism, FTIR, dynamic light scattering, physical stability, confocal laser scanning microscopy, and microrheology measurements. Compared with LF alone, the presence of xanthan gum (XG) inhibited the exposure of hydrophobic core in LF caused by HPP to a certain extent. HPP slightly changed the secondary structure of LF, while the addition of XG expanded the effect. 200 MPa treatment was favorable for LF-XG complexes to form ordered structure, while higher pressure decreased the content of & alpha;-helix. HPP treatment or XG addition both led LF molecules to unfold, while the combination of them caused LF to fold under certain conditions. Droplet sizes of LF-XG stabilized emulsions were smallest under 400 MPa. HPP increased the charges on the surface of droplets. HPP caused the oil droplets closer to spherical, more evenly distributed and reduced the flocculation among droplets. The Addition of 0.3 wt% XG or combination of 0.2 wt% XG and HPP could maximize the physical stability of emulsions. By altering the molecular structure of LF or LF-XG, HPP, and XG increased the viscoelasticity of emulsions.