Turning invasive green crab (Carcinus maenas) into opportunity: recovery of chitin and protein isolate through isoelectric solubilization/precipitation.
Purpose: The potential of the isoelectric solubilization/precipitation (ISP) process as a sustainable method for recovering value-added bio-products from invasive European green crab was investigated. Methods: Protein isolate and chitin were extracted from green crab through ISP procedure. Both bio-products were characterized in terms of physicochemical composition. Protein profile and surface morphology were also determined for the extracted protein isolate and chitin, respectively. Results: Green crab proteins were mostly soluble at neutral and alkaline pH values (> 88%). The minimum green crab protein solubility (40.40%), corresponding to the isoelectric pH, occurred at pH 4.0. The application of the ISP process to green crab resulted in the generation of two fractions: crab protein isolate and chitin-rich crab shell, with high recovery yields (83.35 and 88.92%, respectively, on a dry weight basis). The recovered protein isolate contained high protein and fat contents and low ash level (68.60, 11.95 and 0.71%, respectively, on a dry basis). The recovered crab shell contained 11.25% chitin, which was nearly twice the amount of chitin in the whole green crab. Chitin extracted from the shell after the application of the ISP process did not differ from that extracted directly from the whole green crab. Both chitins had similar (P > 0.05) degree of deacetylation (31.0 and 32.4%, respectively) as well as similar surface morphology as revealed by scanning electron microscopy (SEM). Conclusions: The present study demonstrated that protein isolate and chitin rich shell can efficiently be recovered from green crab using isoelectric solubilization/precipitation and subsequently be used as value-added bio-products.