2.3. Microencapsulation process
2.3.1. Protraction of standard curve
The tetraiodofluorescein sodium salt in a dissolved state had the
same maximum absorbance wavelength as RRP extract in solution.
Its standard curve is commonly used in biochemical analyses and
was used to draw the standard curve for RRP.
2.3.2. Calculation of embedding rate of microencapsulation
Using the techniques of Wu et al. (2005a,b), microencapsulated
sample was dissolved in absolute ethyl alcohol and repeatedly extracted
until the combination of the base layer leuco-organic phase
was achieved. Additional absolute ethyl alcohol was added for the
above layer pigment dissolvent to achieve a volume of 50 ml before
colorimetric assay at 520 nm was carried out using a 722-spectrophotometer
(Super-bio Biotechnology Co., Ltd. Nanjing.), and the
result compared to the standard curve. The microcapsule embedding
rate (MER) was calculated by measuring the content of red
pigments from the above-mentioned 50 ml of dissolved pigments
(Ci), the content of pigment on the surface of microcapsule (Cs)
and the quantity of pigment added at the beginning of the microencapsulation
process (Cb) as follows:
MERð%Þ¼ðCi CsÞ=Cb 100% ð