Protein recovery by ultrafiltration during isolation of chitin from shrimp shells Parapenaeus longirostris

In the food processing industry shrimp shells (Parapenaeus longorostris) have great commercial value because they are rich in chitin (24 wt%), protein (40 wt%), lipids, pigments and flavor compounds. In the present study protein recovery by ultrafiltration was examined during isolation of chitin from shrimp shell P. longirostris. Up to 96 wt% of the proteins could be removed (i.e. deproteinization) from the shrimp shells by incubating them in NaOH (2 N) over 2 h, at T = 45 °C, and solid to solvent ratio of 1:2 (w/v). A solute rejection coefficient (R0) of 97% was obtained in the ultrafiltration process to recover proteins from deproteinized shell waste water. The protein concentration process which was carried out beyond the critical flux of 380 L/h.m2, at a trans-membrane pressure of 3 bars, and a tangential velocity of 5 m/s was found to reduce the hydrolysate volume by a factor of 2.4. Due to a reduction in organic matter in the effluent, the chemical oxygen demand (COD) of the permeate was reduced by 87%.