The influence of heat treatment of lactoferrin powders on the physicochemical properties and bacteriostatic activity

Background, Context, or Rationale Lactoferrin (LF) is a multifunctional glycoprotein with remarkable biological activities, but faces challenges in maintaining structural integrity and antimicrobial efficacy during industrial production. Aim(s) The manufacturing process of LF powder involves multiple processing steps, including pasteurisation and drying. The heat treatment processes applied in each step can cause changes in the structure and functional properties. We systematically compared four drying processes and investigated the effects of various drying and sterilisation methods. We are seeking sustainable protein preservation technologies achieving the critical balance between bioactive preservation and manufacturing cost‐efficiency. Methods Four LF samples were prepared using different methods: freeze‐drying, high‐temperature spray drying, low‐temperature spray drying, and pasteurised freeze‐dried. The physicochemical properties, including particle size, surface hydrophobicity, moisture distribution, and thermal stability, were measured using techniques such as sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The antimicrobial properties were evaluated using the zone of inhibition method. Major Findings Physicochemical properties: Low‐temperature spray drying LF exhibited the smallest particle size and superior microstructure compared to high‐temperature spray drying and freeze‐drying. It also showed enhanced thermal stability and wettability. Bacteriostatic activity: Low‐temperature spray drying demonstrated superior antibacterial activity, inhibiting the growth of C. albicans, E. coli and S. aureus . Structural integrity: Low‐temperature spray drying caused the least structural degradation, maintaining better protein functionality compared to high‐temperature spray drying. The fluorescence and Far‐UV Circular Dichroism analysis showed minimal unfolding of LF in low‐temperature spray drying, while high‐temperature spray drying caused more significant denaturation. Scientific or Industrial Implications Low‐temperature spray drying is the most suitable method for preserving LF bioactivity, offering advantages in particle size, structural stability, and bacteriostatic efficacy over high‐temperature spray drying and freeze‐drying. This method is more efficient for industrial‐scale LF production, ensuring the retention of functional properties.