Biomedical Engineering Reference
In-Depth Information
Figure 15. Median diameter of oil droplets in O/W emulsions prepared using acyl ascorbates with
different acyl chains at various concentrations as emulsifiers. The emulsifiers used were (
) octanoyl,
(
U
) decanoyl, (
{
) lauroyl, (
) myristoyl and (
V
) palmitoyl ascorbates. The inner figure shows the
dependence of the median diameter,
d
p
, of oil droplets in the emulsions prepared at an emulsifier
concentration of 0.5 mmol/kg on the carbon number of the acyl chain,
n
.
Figure 16. Stability at 37
o
C of O/W emulsions prepared using (a) octanoyl, (b) decanoyl, (c) lauroyl, (d)
myristoyl and (e) palmitoyl ascorbates at various concentrations as emulsifiers. The concentrations of
each acyl ascorbate were (
) 0.0005, (
U
) 0.005, (
{
) 0.05, (
) 0.5, and (
V
) 5.0 mmol/kg. The
ordinate indicates the absorbance at 500 nm relative to the initial one.
mol/L, the stability of the O/W emulsions greatly depended on the pH value of the aqueous
phase, and the emulsions were more stable at higher pH. Acyl ascorbates, which adsorb on
the surface of oil droplets in O/W emulsions, also seem to have similar p
K
a
values. Therefore,
