β-Lactoglobulin (β-Lg) spherical shape nanoparticles (diameter ranged between 140 to 220 nm) were loaded with caffeine as a model molecule in order to study their suitability as a protective encapsulant against adverse environmental conditions and for the controlled release of caffeine.
Partial degradation of the structure of the β-Lg nanoparticles loaded with caffeine was observed when incubated in a simulating gastric fluid containing pepsin for 10 min at 37°C and pH 1.5 at protein:enzyme ratio 3:1 w/w based on measurements of particle size by dynamic light scattering. After 120 minutes incubation 64% reduction in particle size was observed whilst only 22 % of caffeine was released which suggests that the degraded nanoparticles retain their encapsulating properties under these conditions.
The kinetics of β-Lg nanoparticles degradation fitted a hyperbolic shape model which enabled to estimate the minimum aggregate size upon complete degradation. On the other hand, caffeine was released from the β-Lg nanoparticles following a linear kinetic consequently, particle size does not determine caffeine release. However a good fitting was found between caffeine release and area to volume ratio suggesting that the latter is a key factor in the release of caffeine.
Overall it can be concluded that β-Lg nanoparticles could be used for the effective controlled release of caffeine.
Dr. Paula Jauregi p.jauregi@reading.ac.uk
