Functional improvements in β-conglycinin by conjugation with pectin by the Maillard reaction.

β-Conglycinin was conjugated with pectin by the Maillard reaction to improve its emulsifying property and reduce its allergenicity. Low methoxy pectin (LMP) and high methoxy pectin (HMP) were conjugated with β-conglycinin. Reaction ratio of β-conglycinin and pectin was 1.0: 5.0 (weight ratio). The Maillard Reaction was conducted at 65 °C at 79% relative humidity for 5 days to prepare the β-conglycinin-LMP conjugate and 7 days to prepare the β-conglycinin-HMP conjugate. The β-conglycinin-pectin conjugates were purified by salting out with ammonium sulfate. Conjugation was confirmed by SDS-PAGE. The results of bicinchoninic acid (BCA) method and phenol sulfuric acid method showed that weight ratio of protein and saccharide of the β-conglycinin-LMP and β-conglycinin-HMP conjugates was 1:1.33 and 1:0.73 respectively. The result of o-phthalaldehyde (OPA) method indicated that free amino groups of β-conglycinin were shielded by conjugation with pectin and the degree of shielding was pronounced especially for the β-conglycinin-HMP conjugate. Solubility of β-conglycinin at pH 5.0 was improved by conjugation with LMP. Emulsifying property of β-conglycinin at pH 5.0 and pH 7.0 and in the presence of 0.2 M NaCl was improved by conjugation with pectin, especially with LMP. Antigenicity and immunogenicity of β-conglycinin were reduced by conjugation with HMP.