Ultrafiltration of Milk: Effect on Lactoferrin, Lysozyme, and Lactoperoxidase Activity During Cheddar Cheese Ripening

ABSTRACT Protein fortification by the ultrafiltration (UF) process prior to cheesemaking is gaining traction but the impact on the natural defense of milk (like lactoferrin, lactoperoxidase, lysozyme) remains unknown. The retention of lactoferrin, lactoperoxidase, and lysozyme in cheesemilk concentrated at 5.6% protein by the UF process (before cheesemaking) and on Cheddar cheese properties was studied. Cheesemilks at 5.6% protein were prepared with retentate (2.6×) made by the UF process and compared with a control at 3.35% protein. Lactoperoxidase activity and the concentration of lysozyme and lactoferrin were measured by ELISA assay. Cheese microbiota (lactobacilli, lactococci) and texture were evaluated during ripening (180 days, 8°C). A significant 1.4‐fold increase in lactoferrin concentration was observed at 5.6% protein compared with the control. Lactoferrin and lactoperoxidase remained active throughout the 180 days of ripening, maintaining 95% and 63% of their initial concentration and activity, respectively. No effect on primary proteolysis, texture, and cheese microbiota was observed suggesting that the protein fortification practice by the UF process had no effect on cheese properties. This work contributed to give new knowledge to the dairy sector on the impact of the growing protein fortification practice on the activity and concentration of three antimicrobial proteins, and part of the natural defense of milk. Protein fortification by the UF process could be used as an additional tool to enhance cheese bioactivity. Value‐added dairy products enriched in lactoferrin, without affecting cheese properties, could be developed by the dairy sector, providing additional incentive to consumers.