Optimization of enzymatic hydrolysis of shrimp waste for recovery of antioxidant activity rich protein isolate.

Shrimp waste is an important source of astaxanthin,
which occur as a complex with proteins, and protein
isolates as well as carotenoids are known to possess antioxidant
activity. Investigations were carried out to optimize
hydrolysis of shrimp waste using a bacterial protease to
obtain antioxidant activity rich protein isolate. The effect
of three process variables namely enzyme concentration to
waste, incubation temperature and time on carotenoid recovery,
protein content, trichloro acetic acid (TCA) soluble
peptide content and DiPhenyl Picryl Hydrazylchloride
(DPPH) scavenging activity was evaluated using a fractionally
factorial design. A high correlation coefficient (>0.90)
between the observed and the predicted values indicated the
appropriateness of the design employed. Maximum carotenoid
recovery was obtained by hydrolysing the shrimp waste
with 0.3 % enzyme for 4 h. DPPH radical scavenging
activity of carotenoprotein isolate was markedly affected
by enzyme concentration, temperature and time of hydrolysis.
The study indicated that in order to obtain the carotenoprotein
from shrimp waste with higher carotenoid content
hydrolysing with an enzyme concentration of 0.2–0.4 %, at
lower temperature of 25–30° upto 4 h is ideal. However, in
order to obtain the protein isolate with increased antioxidant
activity hydrolysing at higher temperature of 50 °C, with
higher enzyme concentration of 0.5 % for shorter duration is
more ideal.