Fresh fish samples were kept in plastic bags and transported in
an insulated icebox to the laboratory. The samples were immediately
de-headed, gutted, and washed with copious amounts of cool
water, and then the flesh and skins were separated using a de-bonner
(model- FD 6, Safe World Food-Tech Pvt. Ltd., Kuala Lumpur).
The flesh, skins, viscera, and heads were stored at 20 C separately,
and then freeze dried (Model: LABCONCO, USA) at a drying
temperature of 47 C and under a vacuum of 0.133 bar. The dried
samples were kept in desiccators until use. For experimental analysis,
the dried samples were ground into particles ranging from 0.2
to 0.5 mm in size by being forced through a sieve.