UTILISATION OF GROUPER PROCESSING WASTE FOR THE RECOVERY OF PROTEINS AND FOR THE PRODUCTION OF ISOLATE HYDROLYSATES
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Date
2019
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR
Abstract
The recovery of proteins from fish processing waste for human consumption is
useful for better utilization of available resources. Proteins from grouper (Epinephelus
diacanthus) fillet frames were recovered using isoelectric solubilization method. Effect of
process variables like pH, time, weight of homogenate to solvent volume ratio and
centrifugation speed on recoveries were studied. pH, weight of homogenate to solvent
volume ratio and centrifugation speed were found to have significant effect (p < 0.05) on
protein recoveries. The optimized conditions for extraction found were- pH-11.0 for alkali
aided process and pH 3.0 for acid aided processes. Extraction time–120min, weight of
homogenate to solvent volume ratio-1:6 and centrifugation speed–10000 rpm. During
isoelectric solubilisation, lipids, myoglobin and pigment contents were reduced by 82.69,
93.91, 79.59% respectively in alkali aided isolate while in acid aided isolate the reduction
percentage was 82.04, 90.77, 70.79% for lipid, myoglobin and total pigment respectively.
The colour of the isolates also increased significantly (p< 0.05) as compared to raw
material.
Hydrolysates were prepared from the recovered protein isolates by using two
enzymes – alcalase and papain. Hydrolysis conditions like E/S ratio, pH, hydrolysis
temperature and hydrolysis time were optimized for both enzymes. The degree of
hydrolysis was more in hydrolysates prepared by using alcalase than papain. Significant
difference (p< 0.05) was found in DPPH radical scavenging activity and ferric reducing
power assay in mince and protein isolate hydrolysates. There was significant difference
(p<0.05) in EAI, ESI, FC and FS of the hydrolysates prepared by using alcalase and
papain.