The protective effect of blg/Lyso microspheres against photochemical
degradation of D3 was assessed by exposing the
D3-loaded blg/Lyso microspheres and unprotected D3 to intensive
UV-light for 24 h. The fitted curves obtained from non-linear
regression are presented in Fig. 2. After 2 h of exposure to UV-light,
about 98.8% of the unprotected D3 was degraded while 35% of
entrapped-D3 in the blg/Lyso microspheres still remained intact.
Total loss was obtained after 6 h of irradiation for the unprotected
D3 while it was only after 24 h that 97% of D3 entrapped in the blg/
Lyso microspheres was degraded (Fig. 2A). The rapid degradation
of the unprotected D3 and the importance of the shielding effect
of the blg/Lyso microspheres is confirmed by the equivalence test
(Fig. 2B). The protective effect of the blg/Lyso microspheres against
the photochemical degradation of D3 can also be attributed to the
dense protein matrix composed of amino acids with aromatic side
groups and double bonds which can absorb UV-light and thus
reduce the absorption of UV-light by the vitamin (Luo, Teng, &
Wang, 2012). The entrapment of D3 in the protein microsphere
might also provide additional protection by decreasing the
mobility of the vitamin, consequently limiting its reactivity (Ron
et al., 2010). The free thiol responsible for the antioxidant activity
of blg by radical quenchers might also contribute to improved stability
of D3