An Autolytic Process for Recovery of Antioxidant Activity Rich Carotenoprotein from Shrimp Heads

Studies were carried out to utilize in situ
proteases of shrimp heads to recover carotenoproteins
possessing antioxidant activity. Highest protease activity
of the buffer extract was found at pH 8.0 (9.85±0.61 units).
The protease activity increased with temperature up to 50°C
and reduced thereafter with highest activity being 19.32±
2.0 units. Thus, the autolysis of shrimp heads for recovery
of carotenoprotein was carried out at pH 8.0 and at 50°C.
Waste to buffer ratio had a significant (p<0.05) effect on
recovery of carotenoids in carotenoprotein filtrate with a
maximum of 58.5±6.4% recovery with a waste to buffer
ratio of 1:2.5 (w:v). The carotenoid recovery increased
significantly to 63.4%±3.6% at the end of a 4-h autolysis.
The studies on combined effect of waste to buffer ratio and
autolysis time indicated increase in protein recovery with
increase in waste to buffer ratio but not with autolysis time.
DPPH scavenging activity of the carotenoprotein isolate
increased with autolysis time up to 100 min, and thereafter,
reduced above 160 min of autolysis time. With increase in
waste to buffer ratio, the scavenging activity increased,
reaching more than 12.5 mg TBHQ equivalent/mg protein
at waste to buffer ratio of 1:5. The optimum autolysis
condition for obtaining antioxidant activity rich carotenoprotein
from shrimp heads was found to be waste to buffer
(pH 8.0) ratio of 1:5 and an autolysis time of 2 h at 50°C.
The isolated carotenoprotein was found to have antioxidant
activity with respect to singlet oxygen quenching, reducing
power and metal chelating activity.