Improved emulsifying property and reduced immunogenicity of β-lactoglobulin by conjugation with carboxymethyl cellulose of different molecular weight.

β-lactoglobulin (BLG) was conjugated with carboxymethyl cellulose (CMC) by using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide to improve its function. Three CMCs differing in molecular weight (1, 90, and 700 kDa) were used to investigate the effect of molecular weight of conjugated saccharide on the degree of functional changes. Reaction ratio was amino groups of BLG: carboxy groups of CMC: 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) = 1:3.5:20 (molar ratio). Conjugation was confirmed by sodium dodecyl sulfate poly acrylamide gel electrophoresis. Composition of the BLG-low molecular weight (LMW) CMC, BLG-middle molecular weight (MMW) CMC, and BLG-high molecular weight (HMW) CMC was BLG: CMC = 1:1.26, 1:1.30, and 1:1.26 (weight ratio), respectively. Emulsifying property of BLG in the acidic pH range and in the presence of NaCl was much improved by conjugation with CMC and the conjugation with HMW CMC was particularly effective. Immunogenicity of BLG was reduced by conjugation with CMC. In particular, conjugation with MMW CMC was effective and brought about not only quantitative but also qualitative improvements.