Abstract:

Casein micelle, as a natural nano-capsular vehicle for nutraceuticals, has the properties of low solubility andemulsifying ability at pH near the isoelectric point. Casein-dextran conjugates via Maillard reaction are expected toovercome these problems. In this work, the aggregation behavior and pH dependence of casein-dextran conjugates separatedthrough ultrafiltration were explored by using fluorescence spectroscopy and dynamic light scattering. The results showedthat casein-dextran conjugates began to self-assemble when the concentration of casein exceeded 0.4 mg/mL. The conjugatedmicelles had a compact structure or a relatively loose structure under different pH conditions. The structures of micelles atpH near the isoelectric point were the most compact, and presented a good stability due to the steric hindrance. Meanwhile,the emulsifying activity and emulsion stability of the conjugated micelles were increased by 2.17 and 3.33 times at pH nearthe isoelectric point, respectively. Therefore, the pH dependence of casein-dextran conjugate micelles might provide morechoices for their use in the field of nutraceutical nanocarriers.

Key words: casein, Maillard reaction, micelles, structure；fluorescence spectroscopy