title: Advanced characterisation of encapsulated lipid powders regarding microstructure by time domain-nuclear magnetic resonance.
abstract: Encapsulation is an established technique to protect sensitive materials from environmental stress. In order to understand the physical protection mechanism against oxidation, knowledge about the powder microstructure is required. Time domain-nuclear magnetic resonance (TD-NMR) has the potential to determine the surface oil (SO) and droplet size distribution by relaxation and restricted self-diffusion, respectively. The amount of SO, the retention and encapsulation efficiency are determined based on a lipid balance. The oil load of the initial powder and after SO removal is measured by TD-NMR. The results correlate with gravimetric and photometric references. The oil droplet size obtained by TD-NMR correlates well with static light scattering. The diameter of droplets in emulsions and dried powder both measured by TD-NMR, correlates (r = 0.998), implying that oil droplets embedded in a solid matrix can be measured. Summarising, TD-NMR allows analysis of the microstructure of encapsulated lipid powders, in a rapid, simple and non-destructive way.
authors.affiliation: a Department of Process Engineering and Food Powders , University of Hohenheim , Stuttgart , Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Linke
authors.affiliation: a Department of Process Engineering and Food Powders , University of Hohenheim , Stuttgart , Germany.
authors.forename: Theresa
authors.initials: T
authors.lastname: Anzmann
authors.affiliation: b Department of Food Physics and Meat Science , University of Hohenheim , Stuttgart , Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
authors.affiliation: a Department of Process Engineering and Food Powders , University of Hohenheim , Stuttgart , Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kohlus
mesh_terms: D008055:Lipids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010316:Particle Size; D011208:Powders / Q000032:analysis*; D013678:Technology, Pharmaceutical
chemical_list: D008055:Lipids; D011208:Powders
keywords: Microencapsulation; encapsulation efficiency; oil droplet size distribution; retention efficiency; structure; time domain-nuclear magnetic resonance