Microencapsulation of a low-trans fat in trehalose as affected by emulsifier type

A low-trans fat blend formulated with high linoleic sunflower seed oil (SFO) and a high melting fraction (HMF) of milk fat was encapsulated by freeze-drying emulsions. The selected emulsifiers were a mixed of the palmitic sucrose esters (SE) P-170 and P-1670, sodium caseinate (NaCas) or a blend of SE and NaCas. The ability to retain the core material with time was studied by storing the powders at different water activities (a(w)). Efficiency of encapsulation was strongly dependent on emulsifier type. NaCas formulation was more efficient retaining core material during storage. The formulation with a protein and a small surfactant had the lowest performance. The stabilizer also influenced droplet size distribution and matrix crystallinity. For NaCas-stabilized powder volume weighted mean diameter (D-4,D-3) remained small for up to 2 months of storage (0.56 +/- 0.5 mu m) and then grew notably in agreement with matrix collapse. There were no significant differences in D-4,D-3 with water content. For NaCas/SE-stabilized powder, however, D-4,D-3 was high at the beginning (100 +/- 0.5 mu m) and then decreased most likely due to particle break-up. Although particle size distribution showed the same behavior for all a(w), retention was strongly dependent on water content. Retention with time was determined by the counteracting effects of these factors.