Scope and Limitations of Using Wax to Encapsulate Water-Soluble Compounds - Food Colloids: Self-Assembly and Material Science - page 109

At regular time intervals upon storage, the fat phase of the spreads was
analysed using gas chromatography (GC) for the presence of alkylbenzenes.
Fat phases of the spreads were extracted by melting, centrifugation, and
filtration. Samples were saponified and extracted with n-hexane. The sensitivity
of the GC analysis was 1-3 mg kg 1 .
7.3.4 Analysis of Wax Digestibility
To estimate the ease of digestibility of the wax, an in vitro lipolysis test was
performed. As a reference substance we used Tween 20, which is assumed to
hydrolyse completely. The waxes used were: beeswax, candelilla wax, ricebran
wax, and carnauba wax, all obtained from Koster Keunen (the Netherlands).
Sunflower wax slurry was obtained from the Unilever refinery at Inverno, Italy.
Final sunflower wax was obtained after further fractionation at the Unilever
Vlaardingen pilot plant.
To prepare the wax emulsions, 88.0 g of demineralized water was placed
into a double-walled vessel, connected to a water bath at a temperature of
851C, and 150 mg of xanthan gum (Keltrol RD) was mixed into the water
with an Ultraturrax. A sample of 10.0 g of wax or 2.0 g of Tween 20 was
heated in a glass beaker until melted and then mixed. The liquid lipid phase
was added to the water phase while mixing with the Ultraturrax at 1.5 10 4
rpm for 5 min at 80-851C. By replacing the content of the water bath with
ice water, the emulsion was cooled within 5 min to 201C while stirring at
1 10 4 rpm.
To carry out the lipolysis reaction, an incubation buffer of 150 mM sodium
chloride, 2 mM tris(hydroxymethyl)aminomethane maleate, 95 mM calcium
chloride, and 0.04-wt% Tween 20 was prepared. The pH of the buffer was
adjusted with 1.0 M sodium hydroxide solution to pH ¼ 6.5. For each lipolysis
assay 40 mL of incubation buffer, 10 mL of wax emulsion, and 280 mg of bile
extract were mixed. The lipolysis reaction was started with the addition of 1.80
g of pancreatin powder. During the incubation period of 30 min, automatic
addition of sodium hydroxide solution was performed to maintain a pH value
of 6.5 (pH stat).
The molar amount of sodium hydroxide solution added is equal to the
molar amount of fatty acids formed, which are present after the hydrolysis.
For the wax hydrolysis, it was assumed that pancreatic lipase hydrolyses
1 mol of wax into 1 mol of fatty acid and 1 mol of fatty alcohol. For Tween
20 hydrolysis, it was assumed that pancreatic lipase hydrolyses 1 mol
of Tween 20 into 1 mol of polyoxyethylene sorbitan and 1 mol of lauric
acid. The degree of hydrolysis of the wax was calculated from the molar
amount of added sodium hydroxide divided by the molar amount of wax
present in the incubation medium. The assumed average molecular
masses of the different compounds were 1227 Da (Tween 20), 674 Da
(beeswax, candelilla wax, carnauba wax, and ricebran wax), and 760 Da
(sunflower wax).