Effect of ultra-high-pressure homogenisation on sweet buttermilk

To improve buttermilk (BM) performance in dairy applications and extend the potential delivery of milk fat globule membrane (MFGM) biological activities, the effects of pH and ultra-high pressure homogenisation (UHPH) on the colloidal stability of MFGM and casein (CN) micelles in BM obtained from raw and pasteurised cream were investigated. Sharp decreases in particle size distribution and turbidity were observed as the UHPH pressure increased; this being more severe at alkaline pH. Separation of proteins and phospholipids between the pellet and serum phase by ultracentrifugation revealed more CNs present in the serum phase as loosely associated aggregates at higher pH. CN aggregate size decreased as the UHPH increased. UHPH reduced BM particle size due to the dissociation of the MFGM fragments into smaller phospholipid vesicles. These modifications could ameliorate BM's technological properties, especially gelling, improving its performance and delivery of MFGM health-promoting properties in yoghurt and cheese applications.