Scope and Limitations of Using Wax to Encapsulate Water-Soluble Compounds - Food Colloids: Self-Assembly and Material Science - page 107

Figure 2 Schematic representation of techniques for preparing the wax capsules. Tech-
nique 1 involves deposition on a plate of hot wax with the encapsulated
compound (a 33% solution of citric acid), leading to large particles (1-10
mm). Technique 2 involves stirring in hot vegetable oil of hot wax with the
encapsulated compound (a solution of FITC), followed by cooling while stir-
ring, giving small particles (1-10 m m)
7.3.2 Analysis of Wax Capsules
The leakage test of capsules made by preparation technique 1 involves storage
of the capsules in demineralized water at room temperature in the dark. A
quantity of capsules (2.5 g) was added to 100 mL water. Leakage of citric acid
was quantified by measuring the pH of the outer water phase.
The leakage test of the capsules made by technique 2 basically involves
mixing of freshly made wax 'capsules' (basically a W/O emulsion made from
water + oil + FITC + wax + PGPR) with a W/O emulsion made from water
+ oil + PGPR at a volume ratio of 1:1. After this, some rhodamine was added
to colour the wax and PGPR. Measurement of the leakage rate was performed
by monitoring the concentration of FITC in the 'empty' water droplets of the
second emulsion. This was done using a confocal laser scanning microscope
(CLSM), a Bio-Rad MRC1024 equipped with an Ar/Kr laser combined with a