Xuena Dong^{1, 2}, Yu Liu^{1, 2}, Shengbo Yu¹, Zhao Li¹, Chunyu Wu¹, Yun Chen², ZengLi Gao², Zhishen Mu^{1, 2,}

Lactoferrin powder was produced using three different methods: freeze-drying, spray-drying, and electrostatic spray-drying, with fresh liquid lactoferrin obtained from the industry as the raw material. The study evaluated the effects of these drying methods on the antioxidant capacity, antibacterial activity, degree of denaturation, and secondary structure characteristics of lactoferrin powder. Additionally, the physical and chemical properties of the lactoferrin powders, such as moisture content, particle size distribution, and iron saturation, were examined. The findings indicated that compared to lactoferrin solution, the electrostatic spray-dried (ESDLF) and spray-dried (SDLF) powders exhibited greater denaturation and conformational changes. The α-helix content increased, and the conformation became more stable, which might result in a significant loss of functional properties. In contrast, the denaturation and conformational changes in freeze-dried lactoferrin (FDLF) powder were minimal. Moreover, FDLF powder demonstrated remarkable antibacterial and anti-inflammatory capabilities compared to ESDLF powder and SDLF powders. Notably, at a sample concentration of 10%, the antibacterial efficacy of FDLF powder reached as high as 99%. This study has revealed that the freeze-drying process was the optimal method for minimizing the denaturation rate of lactoferrin and preserving the activity of lactoferrin powder.

Lactoferrin, Freeze-drying, Spray-drying, Electrostatic spray-drying, Drying methods