Preparation and characterization of pigskin polypeptide chelating calcium

In this paper,the combination between collagen polypeptide and calcium gluconate was studied based on the preparation of collagen polypeptide from pigskin gelatin by measuring chelate rate. Plackett-Burman(PB) design and central composite design(CCD) were applied to screen and optimize 7 factors(solidliquid ratio,ratio of collagen polypeptide to calcium gluconate,p H,reaction temperature,reaction time,agitation speed and mixing time) for the calcium binding capacity. The ratio of collagen polypeptide to calcium gluconate,p H and the reaction time were the main factors of chelated calcium by PB design. The optimal chelate condition was determined as : ratio of collagen polypeptide to calcium gluconate 5. 5 ∶ 1( W / W), p H6. 0, reaction time130 min,solid-liquid ratio 1.5∶100,reaction temperature 60 ℃,agitation speed 30 r/min,and mixing time 20 min and the chelate rate of Ca-collagen polypeptide could reach 78.3%. The structure of chelated calcium was characterized by the UV-VIS,FT-IR,SEM and X-ray. The research confirmed the chelating reaction between calcium ion and collagen polypeptide,and the coordination reaction between calcium and carboxyl/amino group of collagen polypeptide occurred.