Freeze-dried capsules prepared from emulsions with encapsulated lactase as a potential delivery system to control lactose hydrolysis in milk

The objective of this work was to study solid/oil/water (S/O/W) emulsions as delivery systems with retained lactase in milk and controlled release during in vitro digestion. Spray-dried lactase powder was suspended in anhydrous milk fat/Span (R) 80 emulsified by sodium caseinate and lecithin (5: 1). The S/O/W emulsion had an encapsulation efficiency of 75%, a hydrodynamic diameter of 292 nm, and a zeta potential of - 17.37 mV. Crosslinking the dialyzed emulsion with transglutaminase eliminated the detection of free lactase after freeze-drying emulsions and the addition of sodium caseinate further preserved lactase activity. The hydrolysis of lactose in full-fat or skim milk after 3-week storage reduced from > 75% for free lactase to < 15% for encapsulated lactase. The encapsulated lactase was released gradually during the simulated digestions to hydrolyze lactose in milk more efficiently than free lactase. The present findings suggest S/O/W emulsions are potential delivery systems to incorporate lactase in milk products.