Synthesis,characterization And Application Of PAAS-SA-PASP Gel Beads

Marine protein hydrolysates contain a large number of biologically active peptides which have unique biological activities.They have been widely used in food,health care and cosmetics industries,because of the special function in immune regulation,tumor suppression,enzyme inhibition,antibacterial,antiviral,antioxidant,anti radiation and etc.The rapid developments of these industries have received the restriction of the quality and safety of active peptides,especially the problems of excessive heavy metals.Removal of heavy metals from marine protein hydrolysates has become the primary mission to ensure the quality and safety of the enzymatic hydrolysates.In this paper,sodium alginate(SA),sodium poly(aspartic acid)(PASP)and sodium polyacrylate(PAAS),which are all green food additives,were used to prepare a kind of novel gel bead for the removal of Cd2+ and Pb2+ from enzymatic hydrolysates.The adsorptions of Cd2+ and Pb2+ on PAAS-SA-PASP gel beads were studied by dynamic experiments.The results show that the adsorptions of Cd2+ and Pb2+ are both in line with pseudo second-order kinetic model.The adsorption capacities are 136.01mg/g for Cd2+ and 176.09mg/g for Pb2+.Optimization of removal Cd2+ from enzymatic hydrolysates made from squid's viscera was investigated by response surface method.In optimum conditions:pH=4.00,t=17.70h,C(NaCl)=0.05mol/L,removal rate of Cd2+ is up to 94.37%.Optimization of removal Pb2+ from enzymatic hydrolysates made from veneriformis was investigated by response surface method.In optimum conditions:pH=2.25,t=25.60h,C(NaCl)=0.02mol/L,removal rate of Pb2+ is up to 90.30%.The percent removal of metal by the PAAS-SA-PASP gel beads could still be maintained at 89.02%level for Cd2+ and 85.37%level for Pb2+ at the fifth cycle.The total nitrogen contents of these two kinds of enzymatic hydrolysate have been reduced by only 7.24%and 6.91%at the fifth cycle,respectively.Researches show that the PAAS-SA-PASP gel bead can be used to the removal of heavy metals from enzymatic hydrolysates,because of high heavy metal removal rate,less loss of nutrients,reusability,safety,simplified operation,and low cost.