Fat supramolecular structure in fat-filled dairy powders: A tool to adjust spray-drying temperatures

Despite the increasing economic impact of fat-filled dairy powders, their manufacture is still empirical. The aim of the study was to understand the mechanisms responsible for fat supramolecular structure in such a dry matrix. For the purpose, emulsions were obtained under controlled manufacturing conditions. Then, they were dried under different inlet air temperatures, leading to different drying kinetics. Fat droplet size was determined in both emulsions and powders. Free fat and surface fat were assessed to characterize fat in the resulting powders. Confocal laser scanning microscopy was used to characterize fat supramolecular structure in situ in the powder particles. Results showed that fat supramolecular structure in fat-filled dairy powders was connected with drying air temperatures, not necessarily with drying kinetics. Inlet air temperature and consequently temperature of the drying droplet had the most significant influence. Such a study considering drying air temperatures and kinetics is essential in elucidating the mechanisms of free fat formation and the presence of fat at the surface of powder particles. Mechanisms underlying fat supramolecular structure in fat-filled dairy powders are proposed: They can be used as a tool to adjust spray-drying air temperatures and kinetics.