Scope and Limitations of Using Wax to Encapsulate Water-Soluble Compounds - Food Colloids: Self-Assembly and Material Science - page 108

Zeiss Axiovert (inverted) microscope. Images were obtained at two different
magnifications: objective 40 (zoom 2) and objective 63 (zoom 2.5), resulting
in image widths of 130 and 65 mm, respectively.
To visualize the water droplets in the oil phase the following excitation/
emission wavelengths were used: water droplets with rhodamine B (excitation,
568 nm; emission, Z585 nm); water droplets with FITC (excitation, 488 nm;
emission, 522 16 nm); water droplets with rhodamine B; and water droplets
with FITC in one W/O emulsion (excitation, 488 + 568 nm; emission, Z585
nm for water droplets with rhodamine B, channel A; and 522 16 nm for water
droplets with FITC, channel B).

7.3.3 Preparation and Analysis of Complex Coacervate Capsules
The following materials were used to make the gelatin/arabic gum complex
coacervate capsules: beef gelatin 250 bloom (Geltec), gum arabic (Merck),
50.3% glutamic dialdehyde solution in water (Acros), ethylbenzene, n-hexyl-
benzene, n-decylbenzene, n-tetradecylbenzene, n-octadecylbenzene (Aldrich),
and refined sunflower oil from the Unilever Vlaardingen pilot plant. Table 2
gives the K O/W value of the encapsulated oil-soluble alkylbenzenes.
A 2-wt% solution of gum arabic in 1 L of demineralized water was prepared,
with the gum added while stirring at 601C. A 2-wt% solution of gelatin in 1 L of
demineralized water was prepared, with the gelatin added while stirring at 601C.
The gum arabic and gelatin solutions were mixed together at 601C while stirring
at 150 rpm. To this aqueous mixture of gelatine + gum arabic, 100 g of
sunflower oil was added, together with 3 mmol of the specific alkylbenzene.
The mixture was stirred with an Ultraturrax mixer for 1 min at 1.35 10 4 rpm,
with 1.0 M hydrochloric acid added while stirring until a pH of 4.2 was reached.
The vessel was then slowly cooled to 51C, the solution was decanted, and 2 L
of fresh water was added. Some 0.25 g of glutaric dialdehyde solution (50%)
was added to 180 mL water containing 100 g of coacervate, and mixed for 18 h
at approximately 201C. Water was removed by paper filtration, and the capsules
were washed several times to reduce the amount of cross-linking agent. In the
last washing step 0.1% potassium sorbate was added. The capsules were
mixed into a 70% fat margarine spread ('Bona') to a concentration of 5%,
and stored at 51C.

Table 2 Octanol-water partition coefficients and molecular weights of oil-soluble
alkylbenzenes encapsulated in complex coacervate capsules

Component Log (K O/W ) Molecular weight (Da)

Ethylbenzene 3.03 106.2

n-Hexylbenzene 5.00 162.3

n-Decylbenzene 6.96 218.4

n-Tetradecylbenzene 8.92 274.5

n-Octadecylbenzene 10.89 330.6