With the increase of the temperature of water bath, the content
of colorants in extractive solution increased duratively and got to
the best yield at 90
C. It may be understood that the reflux of
ethanol inflask is very good at 90
C of water bath, which could
help the solid materials tittuping well in the boiling ethanol so that
the pigments could be extracted out easily. The content of colorants
in extracted solution increased firstly with ascending ratio of solvent to material and got a high value at 4 mL/g of the ratio of solvent
to material. And the content at 4 mL/g was about 96.6% of that at
6 mL/g. But, they werefirstly increased with an extended time in
the range of 0.5e1.5 h and got to the best yield at 1.5 h of extraction
time, then they decreased smally. It may be understood that some
unstable pigments are decomposed in a long time of high temperature. So, the optimal conditions for extraction of red pigments
by single-factor experiments were summarized as follows. The
residues removed capsaicinoids with 4 mL/g of 95% ethanol were
refluxed for 2 h at 90
C of water bath