Characteristics of bovine lactoferrin powders produced through spray and freeze drying processes

Bovine lactoferrin (LF_b) powders were produced using spray drying and freeze drying. Industrially obtained fresh liquid-LF_b was used as starting material. The antioxidant capacity, solubility in water, moisture sorption behaviour, the extent of denaturation and changes in the secondary structural features of spray-dried (SDLF_b) and freeze-dried bovine lactoferrin (FDLF_b) powders were determined. The residual moisture content, water activity, particle size and amorphous/crystalline nature of the SDLF_b and FDLF_b were also measured. Results showed that both SDLF_b and FDLF_b powders had negligible denaturation and conformation changes compared to the liquid-LF_b. Both SDLF_b and FDLF_b showed type II sorption behaviour with almost identical monolayer moisture content. The SDLF_b powders were amorphous in nature with >98% solubility in water. The antioxidant activity of SDLF_b was similar to that of the liquid-LF_b while it was ∼6% less in FDLF_b. Based on the residual moisture content, water activity, solubility and preservation of secondary structure of LF_b in resultant powders, a spray drying process with 180°C inlet and 95°C outlet temperature was found to produce similar or better quality LF_b powders compared to the ones produced through a freeze drying process.