Preparation and characterization of nanostructured lipid carriers based on sheep tail fat

Nanostructured lipid carriers (NLC) have been widely used for the delivery of bioactive compounds. Sheep tail fat comprises both high- and low-melting-point lipids, making it a natural lipid matrix for producing NLC. Herein, NLC were prepared using sheep tail fat as the lipid matrix, and their physicochemical, crystallization, and digestive properties and quercetin (Qc) delivery efficiency were investigated. Results revealed that the particle size of NLC solidified at 4-25 °C ranged from 251 to 285 nm during 60 days. Tween 40 and 60 promoted heterophane nucleation in NLC, whereas Tween 20 and 80 promoted homogeneous nucleation. Heterophane nucleation may form fewer, larger internal crystals in the NLC, which may have disrupted the interfacial film and resulted in Qc leakage and decreased bioaccessibility. NLC stabilized with Tween 80 (T80-NLC) and solidified at 25 °C showed the maximum Qc encapsulation efficiency of 82.9 % and the maximum bioaccessibility of 42.8 %. However, when the solidification temperature was decreased to 4 °C, the bioaccessibility of T80-NLC reduced to 19.3 %, likely because the crystallization of NLC may disrupt their interfacial structure.