3.3.3 Effect of extraction pressure

3.3.3 Effect of extraction pressure and temperature
The extraction pressure has some effect on the
activity remaining of IGF-1 in the residue. It is seen
from Fig. 6 that as the pressure increases from 10 to
30 MPa, the remaining ratio of IGF-1 is slightly improved.
At 30 MPa, the activity remaining of IGF-1 in
the residue is 93.68%. When the extraction pressure
increases to 40 MPa, the activity remaining of IGF-1
in residue is reduced drastically.
The influence of temperatures (35, 50, 65, and
80°C) on the activity remaining of IGF-1 is shown in
Fig. 6. The results indicate that a lower temperature is
beneficial for keeping IGF-1. Since many water-soluble
proteins, glycosaminoglycan, collagen protein and
keratin exist in anlter velvet, the proteins may denature
and the viscosity of whole system will increase
with temperature. When the extraction temperature is
35°C, the retention of IGF-1 is the highest.
3.3.4 Effect of extraction time
The extraction time is associated with the contact
time between the co-solvent and material. Longer extraction
time and more residual organic solvent will
result in a higher degree of degeneration of the active
components. It is seen from Fig. 6 that when the time
is going on, the remaining ratio of IGF-1 decreases. At
30 min, the activity remaining of IGF-1 in the residue
is 93.68%. Therefore, appropriate extraction time of
30 min is determined.
Considering all the results, the following experimental
conditions were selected as optimum: When
the co-solvent was 75% ethanol, the extraction pressure
was 30 MPa, the extraction temperature was 35°C, the
extraction time was 30 min, and the consumption of
CO2 was 15 L·g