Scope and Limitations of Using Wax to Encapsulate Water-Soluble Compounds - Food Colloids: Self-Assembly and Material Science - page 111

Figure 4 Confocal micrographs of a mixture of FITC-loaded and wax-stabilized water
droplets (whitish on the inside) and 'empty' water droplets (dark on the inside).
Rhodamine B colours the wax and PGPR is situated at the interface. Top
images are for samples one-hour old. Bottom images are for samples stored
chilled for one week. Image widths: 130 m m (left-hand side) and 65 m m (right-
hand side)
In Figure 4 we see that the FITC-filled droplets have an irregular structure at
the interface, originating from the presence of the wax particles. The 'empty'
droplets have a smooth interface because they are stabilized by PGPR. We can
speculate that there is Pickering stabilization by the wax particles 21 on top of
the molecular steric stabilizing effect of the PGPR.
In the one-hour-old samples we clearly notice two types of droplets: one
type containing FITC (white) and the other type not containing FITC (black).
We conclude from this that the FITC does not leak from one droplet to
the other over a time period of an hour. In the one-week-old samples, however,
we notice an increase in FITC content of the droplets with the smooth
interfaces, i.e., those droplets which were depleted in FITC and wax. This
shows that wax-stabilized water droplets in an oily environment cannot retain
water-soluble compounds over a storage period of a week or longer. The
retention is here nevertheless better than described previously by Bodmeier
et al., 12 probably because the waxy water droplets in this study are immersed
in oil.