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Chitin and Chitosan obtained from the crustaceans are having more biological value such as physiological compatibility, non-toxicity, bio digestibility, adsorption and chelating capacity. These biological values of chitosan depend on the quality parameters which are directly related to the source of the raw material. In this study, three commercially available crustacean shell waste such as shrimp, crab and squilla were used for the extraction of chitin and chitosan. The chemical treatment of demineralization, deproteinization and deacetylation were used for the production of chitosan. The viscosity quality parameter of the shrimp chitosan (5300cPs) was better than the crab and squilla chitosan. It is due the high solubility (97.65%) of the shrimp chitosan in 1% acetic acid. The degree of deacetylation of the shrimp chitosan (81.24%) directly relates the solubility of the chitosan. The chitosan with these quality parameters considered to be the excellent biological value. The yield of shrimp chitosan (15.4%) was also more when compare to crab and squilla chitosan. These result showed that utilisation of shrimp shell waste for the production of chitin and chitosan will give more economical and biological value along with reduction of environmental pollution.

Biopeptides derived from fish protein hydrolysates are gaining popularity as active ingredients in functional foods. In this study, squid protein hydrolysates (SPH) prepared from Uroteuthis (Photololigo) duvaucelii, using alcalase and their biopeptides fractionated using ultrafiltration were investigated for their antioxidant properties in relation to the changes in their amino acid profiles. Squid mantle hydrolysed within 30 min with a degree of hydrolysis (DH) of 13.7%. SPH had 89% 2, 2-diphenyl-1-picrylhydrazyl (DPPH) inhibition, 94% 2, 2-azino-bis-(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) inhibition and 96% hydroxyl inhibition at 10 mg ml -1 concentration. In the squid peptides, DPPH inhibition increased with the decrease in the molecular size of peptides from 51% to 95% (3 Ka), ABTS radical inhibition was <42% for peptides with >5KDa size and >95% for peptides with <5KDa. Hydroxyl radical inhibition increased from 75-98% with decrease in molecular size. Increase in glycine, alanine, leucine and taurine was noticed in peptides with MW <5KDa along with a decrease in methionine and arginine. Histidine, asparagine and tyrosine had also contributed to the activities of peptides with MW 3-5 KDa sizes. This study indicated that peptides with MW <5KDa had more free radicals scavenging activities with more hydrophobic amino acids, tyrosine and taurine which are mainly responsible for antioxidative properties. Therefore, squid peptides with MW <5KDa prepared using alcalase have potential to serve as nutraceuticals.

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