conditions, the temperature of water bath was a crucial parameter
and the ratio of solvent to material was also an important
parameter for the high yield of capsaicinoids. And the
extracting time seemed to be effect. In the range of
40%-60% (v/v) concentration of ethanol aqueous, the effect on
extraction yield of capsaicinoids was small which is according with
that of single-factor experiments.
Considering the results of single-factor experiment and the
results of orthogonal array design comprehensively, the optimal
conditions of extracting capsaicinoids from FRPs were summarized
as follows: The extractive temperature of water bath was at
90 C; the ratio of solvent to material was 4 (mL/g); the extractive
time was 120 min; and the concentration of ethanol was 40%-
50%.
In Fig. 5(B), the contents of red pigments were calculated out
from regression equations in 3.1.2, which were used to describe
the total amount of red pigments obtained from 1 g FRPs in this
work. The contents of red pigments in the extracted solution
showed also significant variation for nine experiments. The contents
of red pigments in group 7, 9 were higher than those of
others. The best one in all groups was group 9, which shows an
about 2.5-fold difference when compared to the lowest group.
The different parameters were also analyzed statistically and
the results were summarized in Table 2. Under the experimental
conditions, the concentration of ethanol aqueous was a crucial
parameter for the extraction of red pigments, meanwhile
the extraction temperature of water bath and the ratio of
solvent to material were also important parameter for
the high yield of red pigments. In the range of 90-150 min of
extracting time, the effect on extraction yield of red pigment was
small.
Comprehensively considering the results of single-factor
experiment and the results of orthogonal array design, the
optimal conditions of extraction of red pigments from the residues
after removal of capsaicinoids were summarized as follows. The
concentration of ethanol was 95%; the extractive temperature of
water bath was at 90 C; the ratio of solvent to material was 4 (mL/
g); the extractive time was 120 min.