Proteomic analysis of polysaccharide-milk protein interactions induced by chitosan.
The chitosan-induced coacervation of milk proteins was investigated using a proteomic approach. The addition of 0.8% chitosan to milk caused the milk proteins to coacervate after a 1 h incubation period. Approximately 86% of the milk proteins were present in the milk pellet fraction (MPF), and the protein concentration of the milk supernatant fraction (MSF) decreased from 29.4±0.2 to 4.2±0.6 mg/mL. SDS-PAGE analysis showed that the total intensities of serum albumin (BSA), αS-casein (αS-CN), β-casein (β-CN), κ-casein (κ-CN) and β-lactoglobulin (β-LG) in the MSF decreased to 8.5%±0.2%, 0.9%±0.3%, 0.7%±0.3%, 0.5%±0.2% and 15.0%±0.5%, respectively. Two-dimensional electrophoresis analysis indicated that αS1-, αS2-, β- and κ-CN and a fraction of the β-LG and BSA were found in the MSF following incubation with 0.8% chitosan. Isothermal titration calorimetry analysis indicated that binding of chitosan to milk proteins is an exothermic reaction based on binding titration curves of milk proteins dispersions with chitosan, and the enthalpy of binding (ΔH) and binding constant (Ka) were -7.85×10(4) cal/mol and 1.06×10(5)/mol, respectively. These results suggested that the addition of 0.8% chitosan causes milk proteins to coacervate due to polysaccharide-protein interactions.
Ph.D. Program in Nutrition & Food Science, Fu Jen Catholic University, Taipei 242, Taiwan. kennath1980@gmail.com.|Department of Food Science, Fu Jen Catholic University, Taipei 242, Taiwan. kennath1980@gmail.com.
Chun-Chi
CC
Chen
Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan. bcchen@gate.sinica.edu.tw.
Shui-Tein
ST
Chen
Ph.D. Program in Nutrition & Food Science, Fu Jen Catholic University, Taipei 242, Taiwan. 075101@mail.fju.edu.tw.|Department of Food Science, Fu Jen Catholic University, Taipei 242, Taiwan. 075101@mail.fju.edu.tw.
Jung-Feng
JF
Hsieh
D000818:Animals; D002364:Caseins / Q000378:metabolism; D048271:Chitosan / Q000378:metabolism*; D003102:Colloids / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D007782:Lactoglobulins / Q000378:metabolism; D008892:Milk / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism*; D011134:Polysaccharides / Q000032:analysis*; D040901:Proteomics / Q000379:methods
D002364:Caseins; D003102:Colloids; D007782:Lactoglobulins; D008894:Milk Proteins; D011134:Polysaccharides; D048271:Chitosan